Snip 52 01 concrete and reinforced concrete structures. Concrete and reinforced concrete structures. Requirements for the calculation of concrete and reinforced concrete elements for strength

SP 63.13330.2012

SET OF RULES

CONCRETE AND REINFORCED CONCRETE STRUCTURES. BASIC POINTS

Concrete and won concrete construction

Design requirements

Updated edition
SNiP 52-01-2003

____________________________________________________________________
Text Comparison of SP 63.13330.2012 with SNiP 52-01-2003, see the link.
- Database manufacturer's note.
____________________________________________________________________

OKS 91.080.40

Date of introduction 2013-01-01

Preface

Rulebook Details

1 CONTRACTOR - NIIZhB named after A.A. Gvozdev - Institute of OJSC "National Research Center "Construction".

Amendment No. 1 to SP 63.13330.2012 - NIIZHB named after A.A. Gvozdev - Institute of JSC "National Research Center "Construction"

2 INTRODUCED by the Technical Committee for Standardization TC 465 "Construction"

3 PREPARED for approval by the Department of Architecture, Construction and Urban Development Policy. Amendment No. 1 to SP 63.13330.2012 has been prepared for approval by the Department of Urban Planning and Architecture of the Ministry of Construction and Housing and Communal Services of the Russian Federation (Ministry of Construction of Russia)

4 APPROVED by order of the Ministry of Regional Development of the Russian Federation (Ministry of Regional Development of Russia) dated December 29, 2011 N 635/8 and put into effect on January 1, 2013. In SP 63.13330.2012 "SNiP 52-01-2003 Concrete and reinforced concrete structures. Basic regulations" amendment No. 1 was introduced and approved by order of the Ministry of Construction and Housing and Communal Services of the Russian Federation dated July 8, 2015 N493/pr, order dated November 5, 2015 N 786/pr "On amendments to the order of the Ministry of Construction of Russia dated July 8 2015 N 493/pr", and came into force on July 13, 2015.

5 REGISTERED by the Federal Agency for Technical Regulation and Metrology (Rosstandart).

In case of revision (replacement) or cancellation of this set of rules, the corresponding notice will be published in the prescribed manner. Relevant information, notices and texts are also posted in the public information system - on the official website of the developer (Ministry of Construction of Russia) on the Internet.

Items, tables, and appendices to which changes have been made are marked in this set of rules with an asterisk.

AMENDED Change No. 2, approved and put into effect by Order of the Ministry of Construction and Housing and Communal Services of the Russian Federation dated December 30, 2015 N 981/pr from March 25, 2016

Change No. 2 was made by the database manufacturer

Introduction

The set of rules was developed by the team of authors of the A.A. Gvozdev Research Institute of Reinforced Concrete Construction - an institute of OJSC "National Research Center "Construction" (work leader - Doctor of Technical Sciences T.A. Mukhamediev; Doctors of Technical Sciences A.S. Zalesov, A.I. Zvezdov, E.A. Chistyakov, Candidate of Technical Sciences S.A. Zenin) with the participation of RAASN (Doctors of Technical Sciences V.M. Bondarenko, N.I. Karpenko, V.I. Travush) and OJSC "TsNIIpromzdanii" "(Doctors of Technical Sciences E.N. Kodysh, N.N. Trekin, Engineer I.K. Nikitin).

1 area of use

The set of rules establishes requirements for the design of concrete and reinforced concrete structures made from heavy, fine-grained, lightweight, cellular and prestressing concrete and contains recommendations for the calculation and design of structures with composite polymer reinforcement.

The requirements of this set of rules do not apply to the design of steel-reinforced concrete structures, fiber-reinforced concrete structures, concrete and reinforced concrete structures of hydraulic structures, bridges, pavements of highways and airfields and other special structures, as well as to structures made from concrete with an average density of less than 500 and over 2500 kg/ m, concrete polymers and polymer concretes, concretes with lime, slag and mixed binders (except for their use in cellular concrete), gypsum and special binders, concretes with special and organic fillers, concrete with a large-porous structure.

2 Normative references

SP 2.13130.2012 "Fire protection systems. Ensuring the fire resistance of protected objects" (with Amendment No. 1)

SP 14.13330.2011 "SNiP II-7-81* Construction in seismic areas"

SP 16.13330.2011 "SNiP II-23-81* Steel structures"

SP 20.13330.2011 "SNiP 2.01.07-85* Loads and impacts"

SP 22.13330.2011 "SNiP 2.02.01-83* Foundations of buildings and structures"

SP 28.13330.2012 "SNiP 2.03.11-85 Protection of building structures from corrosion"

SP 48.13330.2011 "SNiP 12-01-2004 Organization of construction"

SP 50.13330.2012 "SNiP 23-02-2003 Thermal protection of buildings"

SP 70.13330.2012 "SNiP 3.03.01-87 Load-bearing and enclosing structures"

SP 122.13330.2012 "SNiP 32-04-97 Railway and road tunnels"

SP 130.13330.2012 "SNiP 3.09.01-85 Production of prefabricated reinforced concrete structures and products"

SP 131.13330.2012 "SNiP 23-01-99 Construction climatology"

GOST R 52085-2003 Formwork. General technical conditions.

GOST R 52086-2003 Formwork. Terms and Definitions.

GOST R 52544-2006 Rolled welded reinforcement bars of periodic profiles of classes A 500C and B 500C for reinforcing reinforced concrete structures.

GOST 27751-2014 Reliability of building structures and foundations. Basic provisions.

GOST 4.212-80 SPKP. Construction. Concrete. Nomenclature of indicators.

GOST 535-2005 Long-rolled and shaped rolled products made of carbon steel of ordinary quality. General technical conditions.

GOST 5781-82 Hot-rolled steel for reinforcement of reinforced concrete structures. Technical conditions.

GOST 7473-2010 Concrete mixtures. Technical conditions.

GOST 8267-93 Crushed stone and gravel from dense rocks for construction work. Technical conditions.

GOST 8736-93 Sand for construction work. Technical conditions.

GOST 8829-94 Prefabricated reinforced concrete and concrete building products. Load test methods. Rules for assessing strength, stiffness and crack resistance.

GOST 10060-2012 Concrete. Methods for determining frost resistance.

GOST 10180-2012 Concrete. Methods for determining strength using control samples.

GOST 10181-2000 Concrete mixtures. Test methods.

GOST 10884-94 Reinforcing steel thermomechanically strengthened for reinforced concrete structures. Technical conditions.

GOST 10922-2012 Reinforcement and embedded products, their welded, knitted and mechanical connections for reinforced concrete structures. General technical conditions.

GOST 12730.0-78 Concrete. General requirements for methods for determining density, humidity, water absorption, porosity and water resistance.

GOST 12730.1-78 Concrete. Method for determining density.

GOST 12730.5-84 Concrete. Methods for determining water resistance.

GOST 13015-2012 Concrete and reinforced concrete products for construction. General technical requirements. Rules for acceptance, labeling, transportation and storage.

GOST 13087-81 Concrete. Methods for determining abrasion.

GOST 14098-91 Welded connections of reinforcement and embedded products of reinforced concrete structures. Types, design and sizes.

GOST 17624-2012 Concrete. Ultrasonic method for determining strength.

GOST 18105-2010 Concrete. Rules for monitoring and assessing strength.

GOST 22690-88 Concrete. Determination of strength by mechanical methods of non-destructive testing.

GOST 23732-2011 Water for concrete and mortars. Technical conditions.

GOST 23858-79 Welded butt and tee connections for reinforced concrete structures. Ultrasonic quality control methods. Acceptance rules.

GOST 24211-2008 Additives for concrete and mortars. General technical requirements.

GOST 25192-2012 Concrete. Classification and general technical requirements.

GOST 25781-83 Steel molds for the manufacture of reinforced concrete products. Technical conditions.

GOST 26633-2012 Heavy and fine-grained concrete. Technical conditions.

GOST 27005-2012* Lightweight and cellular concrete. Medium density control rules.
________________
*Probably an error in the original. Should read: GOST 27005-2014. - Database manufacturer's note.

GOST 27006-86 Concrete. Rules for the selection of compositions.

GOST 28570-90 Concrete. Methods for determining strength using samples taken from structures.

GOST 31108-2003 General construction cements. Technical conditions.

GOST 31938-2012 Composite polymer reinforcement for reinforcing concrete structures. General technical conditions.

Note - When using this set of rules, it is advisable to check the validity of the reference standards (codes of rules and/or classifiers) in the public information system - on the official website of the national body of the Russian Federation for standardization on the Internet or according to the annually published information index "National Standards", which published as of January 1 of the current year, and according to issues of the monthly published information index "National Standards" for the current year. If a reference standard (document) to which an undated reference is given is replaced, it is recommended to use the current version of this standard (document), taking into account all changes made to this version. If a reference standard (document) to which a dated reference is given is replaced, it is recommended to use the version of this standard (document) with the year of approval (adoption) indicated above. If, after the approval of this standard, a change is made to the reference standard (document) to which a dated reference is given, affecting the provision to which the reference is given, then this provision is recommended to be applied without taking into account this change. If the reference standard (document) is canceled without replacement, then the provision in which a reference to it is given is recommended to be applied in the part that does not affect this reference. Information on the validity of sets of rules can be checked in the Federal Information Fund of Technical Regulations and Standards.

3 Terms and definitions

In this set of rules the following terms with corresponding definitions are used:

3.1 anchoring of reinforcement: Ensuring that the reinforcement accepts the forces acting on it by inserting it to a certain length beyond the design cross-section or by installing special anchors at the ends.

3.2 structural reinforcement: Reinforcement installed without calculation for structural reasons.

3.3 prestressed reinforcement: Reinforcement that receives initial (preliminary) stresses during the manufacturing process of structures before the application of external loads during the operation stage.

3.4 working fittings: Fittings installed according to calculation.

3.5 concrete cover: The thickness of the concrete layer from the edge of the element to the nearest surface of the reinforcing bar.

3.6 concrete structures: Structures made of concrete without reinforcement or with reinforcement installed for structural reasons and not taken into account in the calculation; design forces from all impacts in concrete structures must be absorbed by concrete.

3.7 Deleted.

3.8 reinforced concrete structures: Structures made of concrete with working and structural reinforcement (reinforced concrete structures): design forces from all impacts in reinforced concrete structures must be absorbed by concrete and working reinforcement.

3.9 (Deleted, Amendment No. 2).

3.10 reinforcement coefficient of reinforced concrete: The ratio of the cross-sectional area of reinforcement to the working cross-sectional area of concrete, expressed as a percentage.

3.11 waterproof grade of concrete: An indicator of the permeability of concrete, characterized by the maximum water pressure at which, under standard test conditions, water does not penetrate through the concrete sample.

3.12 grade of concrete for frost resistance: The minimum number of freezing and thawing cycles established by standards for concrete samples tested using standard basic methods, in which their original physical and mechanical properties are preserved within standardized limits.

3.13 self-stressing grade of concrete: The value of prestress in concrete, MPa, established by the standards, created as a result of its expansion with a longitudinal reinforcement coefficient of 0.01.

3.14 grade of concrete by average density: The density value established by the standards, in kg/m, of concrete for which thermal insulation requirements are imposed.

3.15 massive structure: A structure for which the ratio of the surface area open for drying, m, to its volume, m, is equal to or less than 2.

3.16 frost resistance of concrete: The ability of concrete to maintain physical and mechanical properties during repeated alternating freezing and thawing is regulated by the frost resistance grade.

3.17 normal section: Section of an element by a plane perpendicular to its longitudinal axis.

3.18 inclined section: Section of an element by a plane inclined to its longitudinal axis and perpendicular to the vertical plane passing through the axis of the element.

3.19 concrete density: The characteristics of concrete, equal to the ratio of its mass to volume, are regulated by the average density grade.

3.20 ultimate force: The greatest force that can be absorbed by an element or its cross-section with the accepted characteristics of the materials.

3.21 permeability of concrete: The property of concrete to allow gases or liquids to pass through itself in the presence of a pressure gradient (regulated by the waterproof grade) or to provide diffusion permeability of substances dissolved in water in the absence of a pressure gradient (regulated by standardized values of current density and electric potential).

3.22 working height of the section: The distance from the compressed edge of the element to the center of gravity of the tensile longitudinal reinforcement.

3.23 self-stressing of concrete: The compressive stress that arises in the concrete of a structure during hardening as a result of the expansion of cement stone under conditions of limiting this expansion is regulated by the self-stressing grade.

3.24 lap joints of reinforcement: Connection of reinforcing bars along their length without welding by inserting the end of one reinforcing rod relative to the end of the other.

4 General requirements for concrete and reinforced concrete structures

4.1 Concrete and reinforced concrete structures of all types must meet the requirements:

On safety;

According to serviceability;

For durability;

As well as additional requirements specified in the design assignment.

4.2 To meet safety requirements, structures must have such initial characteristics that, under various design impacts during the construction and operation of buildings and structures, destruction of any nature or impairment of serviceability associated with harm to the life or health of citizens, property, the environment, life and health of animals and plants.

4.3 To meet the requirements for serviceability, the structure must have such initial characteristics that, under various design influences, the formation or excessive opening of cracks does not occur, and excessive movements, vibrations and other damage do not occur that impede normal operation (violation of the requirements for the appearance of the structure, technological requirements for the normal operation of equipment, mechanisms, design requirements for the joint operation of elements and other requirements established during the design).

Where necessary, structures must have characteristics that meet the requirements for thermal insulation, sound insulation, biological protection and other requirements.

Requirements for the absence of cracks apply to reinforced concrete structures, which must be impermeable when fully stretched (under pressure from liquids or gases, exposed to radiation, etc.), to unique structures that are subject to increased durability requirements, and also to structures operated in aggressive environments in the cases specified in SP 28.13330.

In other reinforced concrete structures, the formation of cracks is allowed, and they are subject to requirements to limit the width of the opening of cracks.

4.4 To meet durability requirements, the design must have such initial characteristics that for a specified long time it would satisfy the requirements for safety and serviceability, taking into account the influence on the geometric characteristics of structures and the mechanical characteristics of materials of various design influences (long-term exposure to load, unfavorable climatic, technological , temperature and humidity influences, alternating freezing and thawing, aggressive influences, etc.).

4.5 Safety, serviceability, durability of concrete and reinforced concrete structures and other requirements established by the design task must be ensured by fulfilling:

Requirements for concrete and its components;

Requirements for fittings;

Requirements for structural calculations;

Design requirements;

Technological requirements;

Operating requirements.

Requirements for loads and impacts, fire resistance limit, impermeability, frost resistance, limit values of deformations (deflections, displacements, amplitude of vibrations), calculated values of outside air temperature and relative humidity of the environment, for the protection of building structures from exposure to aggressive environments, etc. are established by the relevant regulations documents (SP 20.13330, SP 14.13330, SP 28.13330, SP 22.13330, SP 131.13330, SP 2.13130).

(Changed edition, Amendment No. 2).

4.6 When designing concrete and reinforced concrete structures, the reliability of structures is established in accordance with GOST 27751 by a semi-probabilistic calculation method by using the calculated values of loads and impacts, the design characteristics of concrete and reinforcement (or structural steel), determined using the corresponding partial reliability coefficients based on the standard values of these characteristics, taking into account level of responsibility of buildings and structures.

Standard values of loads and impacts, values of safety factors for loads, safety factors for the purpose of structures, as well as the division of loads into permanent and temporary (long-term and short-term) are established by the corresponding regulatory documents for building structures (SP 20.13330).

Design values of loads and impacts are taken depending on the type of design limit state and design situation.

The level of reliability of the calculated values of the characteristics of materials is established depending on the design situation and the danger of reaching the corresponding limit state and is regulated by the value of the reliability coefficients for concrete and reinforcement (or structural steel).

Calculation of concrete and reinforced concrete structures can be carried out according to a given reliability value on the basis of a full probabilistic calculation if there is sufficient data on the variability of the main factors included in the design dependencies.

(Changed edition, Amendment No. 2).

5 Requirements for the calculation of concrete and reinforced concrete structures

5.1 General provisions

5.1.1 Calculations of concrete and reinforced concrete structures should be made in accordance with the requirements of GOST 27751 for limit states, including:

Limit states of the first group, leading to complete unsuitability for operation of structures;

Limit states of the second group, which impede the normal operation of structures or reduce the durability of buildings and structures compared to the intended service life.

Calculations must ensure the reliability of buildings or structures throughout their entire service life, as well as during the performance of work in accordance with the requirements for them.

Calculations for limit states of the first group include:

Strength calculation;

Calculation of shape stability (for thin-walled structures);

Calculation of position stability (tipping over, sliding, floating).

Calculations for the strength of concrete and reinforced concrete structures should be made from the condition that forces, stresses and deformations in structures from various influences, taking into account the initial stress state (prestress, temperature and other influences) should not exceed the corresponding values established by regulatory documents.

Calculations for the stability of the shape of the structure, as well as for the stability of the position (taking into account the joint work of the structure and the base, their deformation properties, shear resistance in contact with the base and other features) should be made in accordance with the instructions of regulatory documents for certain types of structures.

In necessary cases, depending on the type and purpose of the structure, calculations must be made for limit states associated with phenomena in which there is a need to stop the operation of the building and structure (excessive deformations, shifts in joints and other phenomena).

Calculations for limit states of the second group include:

calculation for crack formation;
calculation of crack opening;
calculation based on deformations.

Calculation of concrete and reinforced concrete structures for the formation of cracks should be made from the condition that the forces, stresses or deformations in structures from various influences should not exceed their corresponding limit values perceived by the structure during the formation of cracks.

Calculation of reinforced concrete structures for crack opening is carried out from the condition that the width of crack opening in the structure from various influences should not exceed the maximum permissible values established depending on the requirements for the structure, its operating conditions, environmental influences and characteristics of materials, taking into account the features corrosion behavior of reinforcement.

Calculation of concrete and reinforced concrete structures by deformations should be made from the condition that deflections, angles of rotation, displacement and amplitudes of vibration of structures from various influences should not exceed the corresponding maximum permissible values.

For structures in which the formation of cracks is not allowed, requirements for the absence of cracks must be ensured. In this case, crack opening calculations are not performed.

BASIC POINTS

UPDATED EDITION
SNiP 52-01-2003

Concrete and won concrete construction.
Design requirements

SP 63.13330.2012

OKS 91.080.40

Preface

The goals and principles of standardization in the Russian Federation are established by Federal Law No. 184-FZ of December 27, 2002 “On Technical Regulation”, and the development rules are established by the Decree of the Government of the Russian Federation “On the procedure for developing and approving sets of rules” dated November 19, 2008 No. 858.

Rulebook Details

1. Performers - NIIZhB im. A.A. Gvozdev - Institute of OJSC "National Research Center "Construction".
2. Introduced by the Technical Committee for Standardization TC 465 "Construction".
3. Prepared for approval by the Department of Architecture, Construction and Urban Development Policy.
4. Approved by Order of the Ministry of Regional Development of the Russian Federation (Ministry of Regional Development of Russia) dated December 29, 2011 N 635/8 and put into effect on January 1, 2013.
5. Registered by the Federal Agency for Technical Regulation and Metrology (Rosstandart). Revision of SP 63.13330.2011 "SNiP 52-01-2003. Concrete and reinforced concrete structures. Basic provisions."

Information about changes to this set of rules is published in the annually published information index "National Standards", and the text of changes and amendments is published in the monthly published information index "National Standards". In case of revision (replacement) or cancellation of this set of rules, the corresponding notice will be published in the monthly published information index "National Standards". Relevant information, notices and texts are also posted in the public information system - on the official website of the developer (Ministry of Regional Development of Russia) on the Internet.

Introduction

This set of rules was developed taking into account the mandatory requirements established in the Federal Laws of December 27, 2002 N 184-FZ "On Technical Regulation", dated December 30, 2009 N 384-FZ "Technical Regulations on the Safety of Buildings and Structures" and contains requirements for the calculation and design of concrete and reinforced concrete structures of industrial and civil buildings and structures.
The set of rules was developed by the team of authors of the NIIZHB named after. A.A. Gvozdev - Institute of OJSC "National Research Center "Construction" (work supervisor - Doctor of Technical Sciences T.A. Mukhamediev; Doctors of Technical Sciences A.S. Zalesov, A.I. Zvezdov, E.A. Chistyakov, Candidate of Technical Sciences . Sciences S.A. Zenin) with the participation of RAASN (Doctors of Technical Sciences V.M. Bondarenko, N.I. Karpenko, V.I. Travush) and OJSC "TsNIIpromzdanii" (Doctors of Technical Sciences E.N. Kodysh, N.N. Trekin, engineer I.K.

1 area of use

This set of rules applies to the design of concrete and reinforced concrete structures of buildings and structures for various purposes, operated in the climatic conditions of Russia (with systematic exposure to temperatures not higher than 50 ° C and not lower than minus 70 ° C), in an environment with a non-aggressive degree of exposure.
The Code of Practice establishes requirements for the design of concrete and reinforced concrete structures made from heavy, fine-grained, lightweight, cellular and prestressing concrete.
The requirements of this set of rules do not apply to the design of steel-reinforced concrete structures, fiber-reinforced concrete structures, prefabricated monolithic structures, concrete and reinforced concrete structures of hydraulic structures, bridges, pavements of highways and airfields and other special structures, as well as to structures made from concrete with an average density of less than 500 and over 2500 kg/m3, concrete polymers and polymer concretes, concretes based on lime, slag and mixed binders (except for their use in cellular concrete), gypsum and special binders, concretes based on special and organic fillers, concrete with a large-porous structure.
This set of rules does not contain requirements for the design of specific structures (hollow-core slabs, structures with undercuts, capitals, etc.).

This set of rules uses references to the following regulatory documents:
SP 14.13330.2011 "SNiP II-7-81*. Construction in seismic areas"
SP 16.13330.2011 "SNiP II-23-81*. Steel structures"
SP 20.13330.2011 "SNiP 2.01.07-85*. Loads and impacts"
SP 22.13330.2011 "SNiP 2.02.01-83*. Foundations of buildings and structures"
SP 28.13330.2012 "SNiP 2.03.11-85. Protection of building structures from corrosion"
SP 48.13330.2011 "SNiP 12-01-2004. Organization of construction"
SP 50.13330.2012 "SNiP 23-02-2003. Thermal protection of buildings"
SP 70.13330.2012 "SNiP 3.03.01-87. Load-bearing and enclosing structures"
SP 122.13330.2012 "SNiP 32-04-97. Railway and road tunnels"
SP 130.13330.2012 "SNiP 3.09.01-85. Production of prefabricated reinforced concrete structures and products"
SP 131.13330.2012 "SNiP 23-01-99. Construction climatology"
GOST R 52085-2003. Formwork. General technical conditions
GOST R 52086-2003. Formwork. Terms and Definitions
GOST R 52544-2006. Rolled welded reinforcement of periodic profiles of classes A500C and B500C for reinforcing reinforced concrete structures
GOST R 53231-2008. Concrete. Rules for monitoring and assessing strength
GOST R 54257-2010. Reliability of building structures and foundations. Basic provisions and requirements
GOST 4.212-80. SPKP. Construction. Concrete. Nomenclature of indicators
GOST 535-2005. Long-rolled and shaped rolled products made of carbon steel of ordinary quality. General technical conditions
GOST 5781-82. Hot rolled steel for reinforcement of reinforced concrete structures. Specifications
GOST 7473-94. Concrete mixtures. Specifications
GOST 8267-93. Crushed stone and gravel from dense rocks for construction work. Specifications
GOST 8736-93. Sand for construction work. Specifications
GOST 8829-94. Factory-made reinforced concrete and concrete building products. Load test methods. Rules for assessing strength, stiffness and crack resistance
GOST 10060.0-95. Concrete. Methods for determining frost resistance. Primary requirements
GOST 10180-90. Concrete. Methods for determining strength using control samples
GOST 10181-2000. Concrete mixtures. Test methods
GOST 10884-94. Reinforcing steel thermomechanically strengthened for reinforced concrete structures. Specifications
GOST 10922-90. Welded reinforcement and embedded products, welded connections of reinforcement and embedded products of reinforced concrete structures. General technical conditions
GOST 12730.0-78. Concrete. General requirements for methods for determining density, humidity, water absorption, porosity and water resistance
GOST 12730.1-78. Concrete. Density determination method
GOST 12730.5-84. Concrete. Methods for determining water resistance
GOST 13015-2003. Reinforced concrete and concrete products for construction. General technical requirements. Rules for acceptance, labeling, transportation and storage
GOST 14098-91. Welded connections of reinforcement and embedded products of reinforced concrete structures. Types, design and dimensions
GOST 17624-87. Concrete. Ultrasonic method for determining strength
GOST 22690-88. Concrete. Determination of strength by mechanical methods of non-destructive testing
GOST 23732-79. Water for concrete and mortars. Specifications
GOST 23858-79. Welded butt and tee connections for reinforced concrete structures. Ultrasonic quality control methods. Acceptance rules
GOST 24211-91. Additives for concrete. General technical requirements
GOST 25192-82. Concrete. Classification and general technical requirements
GOST 25781-83. Steel forms for the manufacture of reinforced concrete products. Specifications
GOST 26633-91. Concrete is heavy and fine-grained. Specifications
GOST 27005-86. Concrete is light and cellular. Average Density Control Rules
GOST 27006-86. Concrete. Squad selection rules
GOST 28570-90. Concrete. Methods for determining strength using samples taken from structures
GOST 30515-97. Cements. General technical conditions.
Note. When using this set of rules, it is advisable to check the validity of reference standards and classifiers in the public information system - on the official website of the national body of the Russian Federation for standardization on the Internet or according to the annually published information index "National Standards", which was published on January 1 of the current year, and according to the corresponding monthly information indexes published in the current year. If the reference document is replaced (changed), then when using this set of rules you should be guided by the replaced (changed) document. If the reference document is canceled without replacement, then the provision in which a reference to it is given applies to the part that does not affect this reference.

3. Terms and definitions

In this set of rules the following terms with corresponding definitions are used:
3.1. Anchoring of reinforcement: ensuring that the reinforcement accepts the forces acting on it by inserting it to a certain length beyond the design cross-section or by installing special anchors at the ends.
3.2. Structural reinforcement: reinforcement installed without calculation for structural reasons.
3.3. Prestressed reinforcement: reinforcement that receives initial (preliminary) stresses during the manufacturing process of structures before the application of external loads during the operation stage.
3.4. Working fittings: fittings installed according to calculations.
3.5. Concrete Cover: The thickness of the concrete layer from the edge of the element to the nearest surface of the reinforcing bar.
3.6. Concrete structures: structures made of concrete without reinforcement or with reinforcement installed for structural reasons and not taken into account in the calculation; design forces from all impacts in concrete structures must be absorbed by concrete.
3.7. Dispersed-reinforced structures (fiber-reinforced concrete, reinforced cement): reinforced concrete structures including dispersed fibers or fine-mesh meshes made of thin steel wire.
3.8. Reinforced concrete structures: structures made of concrete with working and structural reinforcement (reinforced concrete structures); design forces from all impacts in reinforced concrete structures must be absorbed by concrete and working reinforcement.
3.9. Steel-reinforced concrete structures: reinforced concrete structures that include steel elements other than reinforcing steel, working in conjunction with reinforced concrete elements.
3.10. Reinforced concrete reinforcement coefficient: the ratio of the cross-sectional area of the reinforcement to the working cross-sectional area of the concrete, expressed as a percentage.
3.11. Waterproof grade of concrete W: an indicator of the permeability of concrete, characterized by the maximum water pressure at which, under standard test conditions, water does not penetrate through the concrete sample.
3.12. Frost resistance grade of concrete F: the minimum number of freezing and thawing cycles of concrete samples established by standards, tested using standard basic methods, in which their original physical and mechanical properties are preserved within standardized limits.
3.13. Self-stress grade of concrete: the value of prestress in concrete, MPa, established by the standards, created as a result of its expansion at the longitudinal reinforcement coefficient.
3.14. Concrete grade according to average density D: the density value established by the standards, in kg/m3, of concrete for which thermal insulation requirements are imposed.
3.15. Massive structure: a structure for which the ratio of the surface area open to drying, m2, to its volume, m3, is equal to or less than 2.
3.16. Frost resistance of concrete: the ability of concrete to maintain physical and mechanical properties during repeated alternating freezing and thawing is regulated by the frost resistance grade F.
3.17. Normal section: section of an element by a plane perpendicular to its longitudinal axis.
3.18. Inclined section: section of an element by a plane inclined to its longitudinal axis and perpendicular to the vertical plane passing through the axis of the element.
3.19. Density of concrete: the characteristic of concrete, equal to the ratio of its mass to volume, is regulated by the average density grade D.
3.20. Ultimate force: the greatest force that can be absorbed by an element or its cross-section with the accepted characteristics of the materials.
3.21. Concrete permeability: the property of concrete to allow gases or liquids to pass through itself in the presence of a pressure gradient (regulated by the water resistance grade W) or to ensure the diffusion permeability of substances dissolved in water in the absence of a pressure gradient (regulated by standardized values of current density and electric potential).
3.22. Working height of the section: the distance from the compressed edge of the element to the center of gravity of the tensile longitudinal reinforcement.
3.23. Self-stressing of concrete: the compressive stress that arises in the concrete of a structure during hardening as a result of the expansion of cement stone under conditions of limiting this expansion is regulated by the self-stressing grade.
3.24. Lap joints: joining reinforcing bars along their length without welding by inserting the end of one reinforcing bar relative to the end of another.

4. General requirements for concrete
and reinforced concrete structures

4.1. Concrete and reinforced concrete structures of all types must meet the requirements:
on safety;
on serviceability;
in terms of durability,
as well as additional requirements specified in the design assignment.
4.2. To meet safety requirements, structures must have such initial characteristics that, under various design impacts during the construction and operation of buildings and structures, destruction of any nature or impairment of serviceability associated with harm to the life or health of citizens, property, the environment, life is excluded. and animal and plant health.
4.3. To meet the requirements for serviceability, the structure must have such initial characteristics that, under various design influences, the formation or excessive opening of cracks does not occur, and excessive movements, vibrations and other damage do not occur that impede normal operation (violation of requirements for the appearance of the structure, technological requirements for the normal operation of equipment, mechanisms, design requirements for the joint operation of elements and other requirements established during the design).
Where necessary, structures must have characteristics that meet the requirements for thermal insulation, sound insulation, biological protection and other requirements.
Requirements for the absence of cracks apply to reinforced concrete structures, which must be impermeable when fully stretched (under pressure from liquids or gases, exposed to radiation, etc.), to unique structures that are subject to increased durability requirements, and also to structures operated in aggressive environments in the cases specified in SP 28.13330.
In other reinforced concrete structures, the formation of cracks is allowed, and they are subject to requirements to limit the width of the opening of cracks.
4.4. To meet the durability requirements, the design must have such initial characteristics that for a specified long time it would satisfy the requirements for safety and serviceability, taking into account the influence on the geometric characteristics of structures and the mechanical characteristics of materials of various design influences (long-term exposure to load, unfavorable climatic, technological, temperature and humidity influences, alternating freezing and thawing, aggressive influences, etc.).
4.5. Safety, serviceability, durability of concrete and reinforced concrete structures and other requirements established by the design task must be ensured by fulfilling:
requirements for concrete and its components;
requirements for fittings;
requirements for structural calculations;
design requirements;
technological requirements;
operating requirements.
Requirements for loads and impacts, fire resistance limit, impermeability, frost resistance, limit values of deformations (deflections, displacements, amplitude of vibrations), calculated values of outside air temperature and relative humidity of the environment, for the protection of building structures from exposure to aggressive environments, etc. are established by the relevant regulations documents (SP 20.13330, SP 14.13330, SP 28.13330, SP 22.13330, SP 131.13330, SP 122.13330).
4.6. When designing concrete and reinforced concrete structures, the reliability of structures is established in accordance with GOST R 54257 by a semi-probabilistic calculation method by using the calculated values of loads and impacts, the design characteristics of concrete and reinforcement (or structural steel), determined using the corresponding partial reliability coefficients based on the standard values of these characteristics, taking into account level of responsibility of buildings and structures.
Standard values of loads and impacts, values of safety factors for loads, safety factors for the purpose of structures, as well as the division of loads into permanent and temporary (long-term and short-term) are established by the corresponding regulatory documents for building structures (SP 20.13330).
Design values of loads and impacts are taken depending on the type of design limit state and design situation.
The level of reliability of the calculated values of the characteristics of materials is established depending on the design situation and the danger of reaching the corresponding limit state and is regulated by the value of the reliability coefficients for concrete and reinforcement (or structural steel).
Calculation of concrete and reinforced concrete structures can be carried out according to a given reliability value on the basis of a full probabilistic calculation if there is sufficient data on the variability of the main factors included in the design dependencies.

5. Requirements for the calculation of concrete and reinforced concrete
designs

5.1. General provisions
5.1.1. Calculations of concrete and reinforced concrete structures should be made in accordance with the requirements of GOST 27751 for limit states, including:
limit states of the first group, leading to complete unsuitability for operation of structures;
limit states of the second group, which impede the normal operation of structures or reduce the durability of buildings and structures compared to the intended service life.
Calculations must ensure the reliability of buildings or structures throughout their entire service life, as well as during the performance of work in accordance with the requirements for them.
Calculations for limit states of the first group include:
strength calculation;
calculation of shape stability (for thin-walled structures);
calculation of position stability (tipping over, sliding, floating).
Calculations for the strength of concrete and reinforced concrete structures should be made from the condition that forces, stresses and deformations in structures from various influences, taking into account the initial stress state (prestress, temperature and other influences) should not exceed the corresponding values established by regulatory documents.
Calculations for the stability of the shape of the structure, as well as for the stability of the position (taking into account the joint work of the structure and the base, their deformation properties, shear resistance in contact with the base and other features) should be made in accordance with the instructions of regulatory documents for certain types of structures.
In necessary cases, depending on the type and purpose of the structure, calculations must be made for limit states associated with phenomena in which there is a need to stop the operation of the building and structure (excessive deformations, shifts in joints and other phenomena).
Calculations for limit states of the second group include:
calculation for crack formation;
calculation of crack opening;
calculation based on deformations.
Calculation of concrete and reinforced concrete structures for the formation of cracks should be made from the condition that the forces, stresses or deformations in structures from various influences should not exceed their corresponding limit values perceived by the structure during the formation of cracks.
Calculation of reinforced concrete structures for crack opening is carried out from the condition that the width of crack opening in the structure from various influences should not exceed the maximum permissible values established depending on the requirements for the structure, its operating conditions, environmental influences and characteristics of materials, taking into account the features corrosion behavior of reinforcement.
Calculation of concrete and reinforced concrete structures by deformations should be made from the condition that deflections, angles of rotation, displacement and amplitudes of vibration of structures from various influences should not exceed the corresponding maximum permissible values.
For structures in which the formation of cracks is not allowed, requirements for the absence of cracks must be ensured. In this case, crack opening calculations are not performed.
For other structures in which the formation of cracks is allowed, calculations based on crack formation are performed to determine the need for calculations based on crack opening and taking cracks into account when calculating based on deformations.
5.1.2. Calculation of concrete and reinforced concrete structures (linear, planar, spatial, massive) according to the limit states of the first and second groups is carried out according to stresses, forces, deformations and displacements calculated from external influences in structures and systems of buildings and structures formed by them, taking into account physical nonlinearity (inelastic deformations of concrete and reinforcement), possible formation of cracks and, in necessary cases, anisotropy, accumulation of damage and geometric nonlinearity (the effect of deformations on changes in forces in structures).
Physical nonlinearity and anisotropy should be taken into account in the constitutive relationships connecting stresses and strains (or forces and displacements), as well as in the conditions of strength and crack resistance of the material.
In statically indeterminate structures, it is necessary to take into account the redistribution of forces in the elements of the system due to the formation of cracks and the development of inelastic deformations in concrete and reinforcement up to the occurrence of a limit state in the element. In the absence of calculation methods that take into account the inelastic properties of reinforced concrete, as well as for preliminary calculations taking into account the inelastic properties of reinforced concrete, forces and stresses in statically indeterminate structures and systems can be determined under the assumption of elastic operation of reinforced concrete elements. In this case, it is recommended to take into account the influence of physical nonlinearity by adjusting the results of linear calculations based on data from experimental studies, nonlinear modeling, calculation results of similar objects and expert assessments.
When calculating structures for strength, deformation, formation and opening of cracks based on the finite element method, the conditions of strength and crack resistance for all finite elements making up the structure, as well as the conditions for the occurrence of excessive movements of the structure, must be checked. When assessing the limit state for strength, it is allowed to assume that individual finite elements are destroyed if this does not entail progressive destruction of the building or structure, and after the load in question expires, the serviceability of the building or structure is maintained or can be restored.
Determination of ultimate forces and deformations in concrete and reinforced concrete structures should be made on the basis of design schemes (models) that most closely correspond to the real physical nature of the operation of structures and materials in the limit state under consideration.
The bearing capacity of reinforced concrete structures capable of undergoing sufficient plastic deformations (in particular, when using reinforcement with a physical yield strength) can be determined by the limit equilibrium method.
5.1.3. When calculating concrete and reinforced concrete structures based on limit states, various design situations should be considered in accordance with GOST R 54257, including the stages of manufacturing, transportation, construction, operation, emergency situations, as well as fire.
5.1.4. Calculations of concrete and reinforced concrete structures should be made for all types of loads that meet the functional purpose of buildings and structures, taking into account the influence of the environment (climatic influences and water - for structures surrounded by water), and, if necessary, taking into account the effects of fire, technological temperature and humidity influences and influences of aggressive chemical environments.
5.1.5. Calculations of concrete and reinforced concrete structures are carried out on the action of bending moments, longitudinal forces, transverse forces and torques, as well as on the local action of the load.
5.1.6. When calculating elements of prefabricated structures for the impact of forces arising during their lifting, transportation and installation, the load from the mass of the elements should be taken with a dynamic coefficient equal to:
1.60 - during transportation,
1.40 - during lifting and installation.
It is allowed to accept lower, justified in accordance with the established procedure, values of the dynamism coefficients, but not lower than 1.25.
5.1.7. When calculating concrete and reinforced concrete structures, one should take into account the peculiarities of the properties of various types of concrete and reinforcement, the influence on them of the nature of the load and the environment, methods of reinforcement, the compatibility of the work of reinforcement and concrete (in the presence and absence of adhesion of reinforcement to concrete), the technology for manufacturing structural types of reinforced concrete elements buildings and structures.
5.1.8. Calculation of prestressed structures should be carried out taking into account the initial (preliminary) stresses and deformations in reinforcement and concrete, losses of prestress and the characteristics of the transfer of prestress to concrete.
5.1.9. In monolithic structures, the strength of the structure must be ensured, taking into account the working joints of concreting.
5.1.10. When calculating prefabricated structures, the strength of the nodal and butt joints of prefabricated elements, carried out by connecting steel embedded parts, outlets of reinforcement and embedding with concrete, must be ensured.
5.1.11. When calculating flat and spatial structures subjected to force influences in two mutually perpendicular directions, individual flat or spatial small characteristic elements separated from the structure with forces acting on the lateral sides of the element are considered. If there are cracks, these forces are determined taking into account the location of the cracks, the stiffness of the reinforcement (axial and tangential), the stiffness of concrete (between cracks and in cracks) and other features. In the absence of cracks, the forces are determined as for a solid body.
In the presence of cracks, it is allowed to determine the forces under the assumption of elastic operation of the reinforced concrete element.
Calculation of elements should be carried out along the most dangerous sections located at an angle relative to the direction of the forces acting on the element, based on calculation models that take into account the work of tensile reinforcement in a crack and the work of concrete between cracks under plane stress conditions.
5.1.12. Calculations of flat and spatial structures can be carried out for the structure as a whole based on the limit equilibrium method, including taking into account the deformed state at the time of destruction.
5.1.13. When calculating massive structures subjected to force influences in three mutually perpendicular directions, individual small volumetric characteristic elements isolated from the structure with forces acting along the edges of the element are considered. In this case, the forces should be determined on the basis of premises similar to those adopted for flat elements (see 5.1.11).
Calculation of elements should be carried out along the most dangerous sections located at an angle relative to the direction of the forces acting on the element, based on calculation models that take into account the operation of concrete and reinforcement under volumetric stress conditions.
5.1.14. For structures of complex configuration (for example, spatial), in addition to calculation methods for assessing bearing capacity, crack resistance and deformability, the results of testing physical models can also be used.
5.2. Requirements for the calculation of concrete and reinforced concrete elements for strength
5.2.1. Calculation of concrete and reinforced concrete elements for strength is carried out:
for normal sections (under the action of bending moments and longitudinal forces) - according to a nonlinear deformation model. For simple types of reinforced concrete structures (rectangular, T- and I-sections with reinforcement located at the upper and lower edges of the section), it is allowed to perform calculations based on ultimate forces;
along inclined sections (under the action of transverse forces), over spatial sections (under the action of torques), under the local action of a load (local compression, punching) - according to ultimate forces.
Calculation of the strength of short reinforced concrete elements (short consoles and other elements) is carried out on the basis of a frame-rod model.
5.2.2. Calculation of the strength of concrete and reinforced concrete elements based on ultimate forces is made from the condition that the force from external loads and influences F in the section under consideration should not exceed the maximum force that can be absorbed by the element in this section

Strength calculation of concrete elements

5.2.3. Concrete elements, depending on their operating conditions and the requirements placed on them, should be calculated using normal sections according to ultimate forces without taking into account (see 5.2.4) or taking into account (see 5.2.5) the resistance of concrete in the tensile zone.
5.2.4. Without taking into account the resistance of concrete in the tensile zone, calculations are made of eccentrically compressed concrete elements at eccentricity values of the longitudinal force not exceeding 0.9 of the distance from the center of gravity of the section to the most compressed fiber. In this case, the maximum force that can be absorbed by the element is determined by the calculated compressive resistance of concrete, uniformly distributed over the conditional compressed zone of the section with the center of gravity coinciding with the point of application of the longitudinal force.
For massive concrete structures, a triangular stress diagram should be taken in the compressed zone that does not exceed the calculated value of the concrete compressive resistance. In this case, the eccentricity of the longitudinal force relative to the center of gravity of the section should not exceed 0.65 of the distance from the center of gravity to the most compressed concrete fiber.
5.2.5. Taking into account the resistance of concrete in the tensile zone, calculations are made of eccentrically compressed concrete elements with an eccentricity of longitudinal force greater than that specified in 5.2.4 of this section, bending concrete elements (which are allowed for use), as well as eccentrically compressed elements with an eccentricity of longitudinal force equal to that specified in 5.2 .4, but in which, according to operating conditions, the formation of cracks is not allowed. In this case, the maximum force that can be absorbed by the cross-section of the element is determined as for an elastic body at maximum tensile stresses equal to the calculated value of concrete resistance to axial tension.
5.2.6. When calculating eccentrically compressed concrete elements, the influence of longitudinal bending and random eccentricities should be taken into account.

normal sections

5.2.7. Calculation of reinforced concrete elements based on ultimate forces should be carried out by determining the maximum forces that can be absorbed by concrete and reinforcement in a normal section, based on the following provisions:
the tensile strength of concrete is assumed to be zero;
the resistance of concrete to compression is represented by stresses equal to the calculated resistance of concrete to compression and uniformly distributed over the conditional compressed zone of concrete;
Tensile and compressive stresses in reinforcement are assumed to be no more than the calculated tensile and compressive resistance, respectively.
5.2.8. Calculation of reinforced concrete elements using a nonlinear deformation model is carried out on the basis of state diagrams of concrete and reinforcement, based on the hypothesis of plane sections. The criterion for the strength of normal sections is the achievement of maximum relative deformations in concrete or reinforcement.
5.2.9. When calculating eccentrically compressed reinforced concrete elements, random eccentricity and the influence of longitudinal bending should be taken into account.

Strength calculation of reinforced concrete elements
inclined sections

5.2.10. Calculation of reinforced concrete elements based on the strength of inclined sections is carried out: along an inclined section for the action of a transverse force, along an inclined section for the action of a bending moment, and along a strip between inclined sections for the action of a transverse force.
5.2.11. When calculating a reinforced concrete element based on the strength of an inclined section under the action of a transverse force, the maximum transverse force that can be absorbed by an element in an inclined section should be determined as the sum of the maximum transverse forces perceived by concrete in an inclined section and transverse reinforcement crossing the inclined section.
5.2.12. When calculating a reinforced concrete element based on the strength of an inclined section under the action of a bending moment, the limiting moment that can be absorbed by the element in the inclined section should be determined as the sum of the limiting moments perceived by the longitudinal and transverse reinforcement crossing the inclined section, relative to the axis passing through the point of application of the resultant forces in compressed zone.
5.2.13. When calculating a reinforced concrete element along a strip between inclined sections under the action of a transverse force, the maximum transverse force that can be absorbed by the element should be determined based on the strength of the inclined concrete strip, which is under the influence of compressive forces along the strip and tensile forces from transverse reinforcement crossing the inclined strip.

Strength calculation of reinforced concrete elements
spatial sections

5.2.14. When calculating reinforced concrete elements based on the strength of spatial sections, the maximum torque that can be absorbed by the element should be determined as the sum of the maximum torques perceived by the longitudinal and transverse reinforcement located at each face of the element. In addition, it is necessary to calculate the strength of a reinforced concrete element using a concrete strip located between the spatial sections and under the influence of compressive forces along the strip and tensile forces from transverse reinforcement crossing the strip.

Local calculation of reinforced concrete elements
load action

5.2.15. When calculating reinforced concrete elements for local compression, the maximum compressive force that can be absorbed by the element should be determined based on the resistance of the concrete under the volumetric stress state created by the surrounding concrete and indirect reinforcement, if installed.
5.2.16. Punching calculations are carried out for flat reinforced concrete elements (slabs) under the action of concentrated forces and moments in the punching zone. The maximum force that can be absorbed by a reinforced concrete element during punching should be determined as the sum of the maximum forces perceived by concrete and transverse reinforcement located in the punching zone.
5.3. Requirements for the calculation of reinforced concrete elements for the formation of cracks
5.3.1. Calculation of reinforced concrete elements for the formation of normal cracks is carried out using limiting forces or using a nonlinear deformation model. Calculations for the formation of inclined cracks are made using maximum forces.
5.3.2. Calculation of the formation of cracks in reinforced concrete elements based on maximum forces is made from the condition that the force from external loads and influences F in the section under consideration should not exceed the maximum force that can be absorbed by a reinforced concrete element when cracks form.

Set of rules. Concrete and reinforced concrete structures. Basic provisions. Updated version of SNiP 52-01-2003" (approved by Order of the Ministry of Regional Development of Russia dated December 29, 2011 N 635/8)

System of regulatory documents in construction

BUILDING STANDARDS AND RULES OF THE RUSSIAN FEDERATION

CONCRETE AND REINFORCED CONCRETE STRUCTURES

Basic provisions

SNiP 52-01-2003

CONCRETE AND REINFORCED CONCRETE STRUCTURES

UDC 624.012.3/.4 (083.13)

Date of introduction 2004-03-01

PREFACE

1 DEVELOPED by the State Unitary Enterprise - Research, Design and Technological Institute of Concrete and Reinforced Concrete "GUP NIIZhB" of the State Construction Committee of Russia

INTRODUCED by the Technical Standardization Department of the Gosstroy of Russia

2 APPROVED AND ENTERED INTO EFFECT by Resolution of the State Committee of the Russian Federation for Construction and Housing and Communal Sector dated June 30, 2003 No. 127 (did not pass state registration - Letter of the Ministry of Justice of the Russian Federation dated October 7, 2004 No. 07/9481-UD)

3 INSTEAD SNiP 2.03.01-84

INTRODUCTION

This regulatory document (SNiP) contains the basic provisions defining the general requirements for concrete and reinforced concrete structures, including requirements for concrete, reinforcement, calculations, design, manufacture, construction and operation of structures.

Detailed instructions for calculations, design, manufacture and operation contain the relevant regulatory documents (SNiP, codes of rules) developed for certain types of reinforced concrete structures in development of this SNiP (Appendix B).

Until the publication of the relevant sets of rules and other developing SNiP documents, it is allowed to use currently valid regulatory and advisory documents for the calculation and design of concrete and reinforced concrete structures.

The following people took part in the development of this document: A.I. Zvezdov, Doctor of Engineering. Sciences - topic leader; Dr. Tech. Sciences: A.S. Zalesov, T.A. Mukhamediev, E.A. Chistyakov are the responsible executors.

1 APPLICATION AREA

These rules and regulations apply to all types of concrete and reinforced concrete structures used in industrial, civil, transport, hydraulic and other areas of construction, made from all types of concrete and reinforcement and subjected to any type of influence.

These rules and regulations use references to the regulatory documents given in Appendix A.

3 TERMS AND DEFINITIONS

These rules and regulations use terms and definitions in accordance with Appendix B.

4 GENERAL REQUIREMENTS FOR CONCRETE AND REINFORCED CONCRETE STRUCTURES

4.1 Concrete and reinforced concrete structures of all types must meet the requirements:

On safety;

According to serviceability;

For durability, as well as additional requirements specified in the design brief.

4.2 To meet safety requirements, structures must have such initial characteristics that, with an appropriate degree of reliability under various design impacts during the construction and operation of buildings and structures, destruction of any nature or impairment of serviceability associated with causing harm to the life or health of citizens, property and environment.

4.3 To meet the requirements for serviceability, the design must have such initial characteristics that, with an appropriate degree of reliability under various design influences, the formation or excessive opening of cracks does not occur, and excessive movements, vibrations and other damage do not occur that impede normal operation (violation of external requirements). type of design, technological requirements for the normal operation of equipment, mechanisms, design requirements for the joint operation of elements and other requirements established during the design).

Where necessary, structures must have characteristics that meet the requirements for thermal insulation, sound insulation, biological protection, etc.

Requirements for the absence of cracks apply to reinforced concrete structures, in which, with a fully stretched section, impermeability must be ensured (pressurized liquids or gases, exposed to radiation, etc.), to unique structures, which are subject to increased requirements for durability, and also to structures operated when exposed to highly aggressive environments.

In other reinforced concrete structures, the formation of cracks is allowed and they are subject to requirements to limit the width of the cracks.

4.4 To meet the durability requirements, the structure must have such initial characteristics that for a specified long time it would satisfy the requirements for safety and serviceability, taking into account the influence on the geometric characteristics of structures and the mechanical characteristics of materials of various design influences (long-term load, unfavorable climatic, technological, temperature and humidity influences, alternating freezing and thawing, aggressive influences, etc.).

4.5 Safety, serviceability, durability of concrete and reinforced concrete structures and other requirements established by the design task must be ensured by fulfilling:

Requirements for concrete and its components;

Requirements for fittings;

Requirements for structural calculations;

Design requirements;

Technological requirements;

Operating requirements.

Requirements for loads and impacts, for fire resistance limits, for impermeability, for frost resistance, for maximum deformation values (deflections, displacements, amplitude of vibrations), for calculated values of outside air temperature and relative humidity of the environment, for the protection of building structures from exposure to aggressive environments and others are established by the relevant regulatory documents (SNiP 2.01.07, SNiP 2.06.04, SNiP II-7, SNiP 2.03.11, SNiP 21-01, SNiP 2.02.01, SNiP 2.05.03, SNiP 33-01, SNiP 2.06. 06, SNiP 23-01, SNiP 32-04).

4.6 When designing concrete and reinforced concrete structures, the reliability of structures is established in accordance with GOST 27751 by a semi-probabilistic calculation method by using the calculated values of loads and impacts, the design characteristics of concrete and reinforcement (or structural steel), determined using the corresponding partial reliability coefficients based on the standard values of these characteristics, taking into account the level liability of buildings and structures.

Standard values of loads and impacts, values of safety factors for loads, as well as safety factors for the intended purpose of structures are established by the relevant regulatory documents for building structures.

Design values of loads and impacts are taken depending on the type of design limit state and design situation.

5 REQUIREMENTS FOR CONCRETE AND REINFORCEMENT

5.1 Requirements for concrete

5.1.1 When designing concrete and reinforced concrete structures, in accordance with the requirements for specific structures, the type of concrete, its standardized and controlled quality indicators (GOST 25192, GOST 4.212) must be established.

5.1.2 For concrete and reinforced concrete structures, types of concrete should be used that meet the functional purpose of the structures and the requirements for them, in accordance with current standards (GOST 25192, GOST 26633, GOST 25820, GOST 25485, GOST 20910, GOST 25214, GOST 25246, GOST R 51263) .

5.1.3 The main standardized and controlled indicators of concrete quality are:

Compressive strength class B;

Axial tensile strength class B t;

Frost resistance grade F;

Waterproof grade W;

Medium density grade D.

Compressive strength class of concrete B corresponds to the cubic compressive strength of concrete in MPa with a probability of 0.95 (standard cubic strength) and is accepted in the range from B 0.5 to B 120.

Concrete class for axial tensile strength B t corresponds to the value of concrete axial tensile strength in MPa with a probability of 0.95 (standard concrete strength) and is taken in the range from B t 0.4 to V t 6.

It is allowed to take a different value for the strength of concrete in compression and axial tension in accordance with the requirements of regulatory documents for certain special types of structures (for example, for massive hydraulic structures).

The frost resistance grade of concrete F corresponds to the minimum number of cycles of alternating freezing and thawing that a sample can withstand during a standard test, and is accepted in the range from F15 to F 1000.

The waterproof grade of concrete W corresponds to the maximum value of water pressure (MPa 10 -1) withstood by the concrete sample during testing, and is accepted in the range from W 2 to W 20.

The average density grade D corresponds to the average value of the volumetric mass of concrete in kg/m3 and is accepted in the range from D 200 to D 5000.

For prestressing concrete, a self-tensioning grade is established.

If necessary, additional indicators of concrete quality are established related to thermal conductivity, temperature resistance, fire resistance, corrosion resistance (both of the concrete itself and the reinforcement contained in it), biological protection and other requirements for the structure (SNiP 23-02, SNiP 2.03. eleven).

The quality indicators of concrete must be ensured by appropriate design of the composition of the concrete mixture (based on the characteristics of materials for concrete and requirements for concrete), technology for preparing concrete and performing work. The performance of concrete is controlled during the production process and directly in the structure.

The required concrete indicators should be established when designing concrete and reinforced concrete structures in accordance with the calculation and operating conditions, taking into account various environmental influences and the protective properties of concrete in relation to the adopted type of reinforcement.

Classes and grades of concrete should be assigned in accordance with their parametric series established by regulatory documents.

Compressive strength class of concrete B is assigned in all cases.

Concrete class for axial tensile strength B t prescribed in cases where this characteristic is of primary importance and is controlled in production.

The frost resistance grade of concrete F is prescribed for structures exposed to alternating freezing and thawing.

The waterproof grade of concrete W is assigned for structures that are subject to requirements for limiting water permeability.

The age of concrete, corresponding to its class in terms of compressive strength and axial tensile strength (design age), is assigned during design based on the possible real terms of loading structures with design loads, taking into account the construction method and concrete hardening conditions. In the absence of this data, the concrete class is established at a design age of 28 days.

5.2 Standard and design values of strength and deformation characteristics of concrete

5.2.1 The main indicators of the strength and deformability of concrete are the standard values of their strength and deformation characteristics.

The main strength characteristics of concrete are standard values:

Resistance of concrete to axial compression Rb , n;

Resistance of concrete to axial tension R bt,n.

The standard value of concrete resistance to axial compression (prismatic strength) should be set depending on the standard value of the strength of cube samples (standard cubic strength) for the corresponding type of concrete and controlled in production.

The standard value of concrete axial tensile strength when assigning a concrete class for compressive strength should be set depending on the standard value of the compressive strength of cube samples for the corresponding type of concrete and controlled in production.

The relationship between the standard values of the prismatic and cubic compressive strengths of concrete, as well as the relationship between the standard values of the tensile strength of concrete and the compressive strength of concrete for the corresponding type of concrete should be established on the basis of standard tests.

When assigning a concrete class for axial tensile strength, the standard value of concrete axial tensile strength is taken equal to the numerical characteristic of the concrete class for axial tensile strength, controlled in production.

The main deformation characteristics of concrete are standard values:

Limit relative deformations of concrete under axial compression and tension e bo , n and e bto , n;

- initial modulus of elasticity of concrete Eb , n.

In addition, the following deformation characteristics are established:

Initial transverse strain coefficient of concrete v;

Concrete shear modulus G;

- concrete thermal deformation coefficient a bt;

Relative creep strains of concrete e cr(or the corresponding creep characteristic j b , cr, a measure of creep Cb , cr);

Relative shrinkage deformations of concrete e shr.

Standard values for the deformation characteristics of concrete should be established depending on the type of concrete, class of concrete in terms of compressive strength, grade of concrete in terms of average density, as well as depending on the technological parameters of concrete, if they are known (composition and characteristics of the concrete mixture, methods of concrete hardening and others parameters).

5.2.2 As a generalized characteristic of the mechanical properties of concrete in a uniaxial stress state, one should take the standard diagram of the state (deformation) of concrete, establishing the relationship between stresses s b , n(s bt , n) and longitudinal relative deformations e b , n(e bt , n) compressed (tensile) concrete under short-term action of a single applied load (according to standard tests) up to their standard values.

5.2.3 The main design strength characteristics of concrete used in the calculation are the design values of concrete resistance:

Axial compression Rb;

Axial tension R bt.

The calculated values of the strength characteristics of concrete should be determined by dividing the standard values of concrete resistance to axial compression and tension by the corresponding safety factors for concrete under compression and tension.

The values of the safety coefficients should be taken depending on the type of concrete, the design characteristics of the concrete, the limit state under consideration, but not less than:

for the safety factor for concrete in compression:

1.3 - for limit states of the first group;

1.0 - for limit states of the second group;

for the safety factor for concrete in tension:

1.5 - for limit states of the first group when assigning a class of concrete in terms of compressive strength;

1.3 - the same when assigning a concrete class for axial tensile strength;

1.0 - for limit states of the second group.

The calculated values of the main deformation characteristics of concrete for the limit states of the first and second groups should be taken equal to their standard values.

The influence of the nature of the load, the environment, the stressed state of concrete, the design features of the element and other factors not reflected directly in the calculations should be taken into account in the calculated strength and deformation characteristics of concrete by the coefficients of concrete operating conditions g bi.

5.2.4 Design diagrams of the state (deformation) of concrete should be determined by replacing the standard values of the diagram parameters with their corresponding design values, accepted according to the instructions of 5.2.3.

5.2.5 The values of the strength characteristics of concrete in a plane (biaxial) or volumetric (triaxial) stress state should be determined taking into account the type and class of concrete from a criterion expressing the relationship between the limiting values of stresses acting in two or three mutually perpendicular directions.

Concrete deformations should be determined taking into account plane or volumetric stress states.

5.2.6 The characteristics of the concrete matrix in dispersed reinforced structures should be taken as for concrete and reinforced concrete structures.

The characteristics of fiber-reinforced concrete in fiber-reinforced concrete structures should be established depending on the characteristics of concrete, the relative content, shape, size and location of fibers in concrete, its adhesion to concrete and physical and mechanical properties, as well as depending on the dimensions of the element or structure.

5.3 Requirements for fittings

5.3.1 When designing reinforced concrete buildings and structures in accordance with the requirements for concrete and reinforced concrete structures, the type of reinforcement and its standardized and controlled quality indicators must be established.

5.3.2 For reinforced concrete structures, the following types of reinforcement, established by the relevant standards, should be used:

Hot-rolled smooth and periodic profiles with a diameter of 3-80 mm;

Thermo-mechanically strengthened periodic profile with a diameter of 6-40 mm;

Mechanically hardened in a cold state (cold-deformed) of a periodic profile or smooth, with a diameter of 3-12 mm;

Reinforcing ropes with a diameter of 6-15 mm;

Non-metallic composite reinforcement.

In addition, steel ropes (spiral, double lay, closed) can be used in long-span structures.

For dispersed reinforcement of concrete, fiber or fine mesh should be used.

For steel-reinforced concrete structures (structures consisting of steel and reinforced concrete elements), sheet and profile steel are used in accordance with the relevant norms and standards (SNiP II-23).

The type of reinforcement should be taken depending on the purpose of the structure, design solution, nature of the loads and environmental influences.

5.3.3 The main standardized and controlled indicator of the quality of steel reinforcement is the reinforcement class for tensile strength, designated:

A - for hot-rolled and thermomechanically strengthened reinforcement;

B - for cold-deformed reinforcement;

K - for reinforcing ropes.

The class of reinforcement corresponds to the guaranteed value of the yield strength (physical or conditional) in MPa, established in accordance with the requirements of standards and technical specifications, and is accepted in the range from A 240 to A 1500, from B500 to B2000 and from K1400 to K2500.

Reinforcement classes should be assigned in accordance with their parametric series established by regulatory documents.

In addition to the requirements for tensile strength, reinforcement is subject to requirements for additional indicators determined according to the relevant standards: weldability, endurance, ductility, resistance to corrosion cracking, relaxation resistance, cold resistance, resistance at high temperatures, elongation at break, etc.

Non-metallic reinforcement (including fiber) is also subject to requirements for alkali resistance and adhesion to concrete.

The necessary indicators are taken when designing reinforced concrete structures in accordance with the requirements of calculations and manufacturing, as well as in accordance with the operating conditions of the structures, taking into account various environmental influences.

5.4 Standard and design values of strength and deformation characteristics of reinforcement

5.4.1 The main indicators of the strength and deformability of reinforcement are the standard values of their strength and deformation characteristics.

The main strength characteristic of reinforcement in tension (compression) is the standard resistance value R s , n, equal to the value of the physical yield strength or conditional, corresponding to the residual elongation (shortening) equal to 0.2%. In addition, the standard values of the resistance of reinforcement under compression are limited to values corresponding to deformations equal to the maximum relative shortening deformations of the concrete surrounding the compressed reinforcement in question.

The main deformation characteristics of reinforcement are standard values:

Relative deformations of elongation of reinforcement e s 0, n when voltages reach standard values R s , n;

Modulus of elasticity of reinforcement E s , n.

For reinforcement with a physical yield strength, standard values of the relative deformation of reinforcement elongation e s 0, n are defined as elastic relative deformations at standard values of reinforcement resistance and its modulus of elasticity.

For reinforcement with a conditional yield strength, standard values of the relative deformation of the elongation of the reinforcement e s 0, n determined as the sum of the residual elongation of the reinforcement equal to 0.2% and elastic relative deformations at a stress equal to the conditional yield strength.

For compressed reinforcement, the standard values of the relative shortening strain are taken to be the same as for tension, with the exception of specially specified cases, but not more than the maximum relative shortening strain of concrete.

The standard values of the modulus of elasticity of reinforcement in compression and tension are assumed to be the same and are established for the corresponding types and classes of reinforcement.

5.4.2 As a generalized characteristic of the mechanical properties of reinforcement, one should take the standard diagram of the state (deformation) of reinforcement, establishing the relationship between stresses s s , n and relative deformations e s , n reinforcement under short-term action of a single applied load (according to standard tests) until their established standard values are reached.

The state diagrams of reinforcement under tension and compression are assumed to be the same, with the exception of cases when the operation of reinforcement is considered, in which there were previously inelastic deformations of the opposite sign.

The nature of the reinforcement state diagram is determined depending on the type of reinforcement.

5.4.3 Design values of reinforcement resistance R s determined by dividing the standard values of reinforcement resistance by the reliability coefficient for the reinforcement.

The values of the safety factor should be taken depending on the class of reinforcement and the limit state under consideration, but not less than:

when calculating using limit states of the first group - 1.1;

when calculating using limit states of the second group - 1.0.

Calculated values of the modulus of elasticity of reinforcement E s are taken equal to their standard values.

The influence of the nature of the load, the environment, the stressed state of the reinforcement, technological factors and other operating conditions not reflected directly in the calculations should be taken into account in the calculated strength and deformation characteristics of the reinforcement by the coefficients of the operating conditions of the reinforcement g si.

5.4.4 Design diagrams of the state of reinforcement should be determined by replacing the standard values of the diagram parameters with their corresponding design values, accepted according to the instructions of 5.4.3.

6 REQUIREMENTS FOR CALCULATION OF CONCRETE AND REINFORCED CONCRETE STRUCTURES

6.1 General provisions

6.1.1 Calculations of concrete and reinforced concrete structures should be made in accordance with the requirements of GOST 27751 using the limit state method, including:

Limit states of the first group, leading to complete unsuitability for operation of structures;

Limit states of the second group, which impede the normal operation of structures or reduce the durability of buildings and structures compared to the intended service life.

Calculations must ensure the reliability of buildings or structures throughout their entire service life, as well as during the performance of work in accordance with the requirements for them.

Calculations for limit states of the first group include:

Strength calculation;

Calculation of shape stability (for thin-walled structures);

Calculation of position stability (tipping over, sliding, floating).

In necessary cases, depending on the type and purpose of the structure, calculations must be made for limit states associated with phenomena in which there is a need to stop operation (excessive deformations, shifts in joints and other phenomena).

Calculations for limit states of the second group include:

Calculation of crack formation;

Calculation of crack opening;

Calculation based on deformations.

For structures in which the formation of cracks is not allowed, requirements for the absence of cracks must be ensured. In this case, crack opening calculations are not performed.

For other structures in which the formation of cracks is allowed, calculations based on crack formation are performed to determine the need for calculations based on crack opening and taking cracks into account when calculating based on deformations.

6.1.2 Calculation of concrete and reinforced concrete structures for durability (based on calculations for the limit states of the first and second groups) should be made from the condition that, given the characteristics of the structure (dimensions, quantity of reinforcement and other characteristics), concrete quality indicators (strength, frost resistance, water resistance, corrosion resistance, temperature resistance and other indicators) and reinforcement (strength, corrosion resistance and other indicators), taking into account the influence of the environment, the duration of the period between repairs and the service life of the structures of a building or structure must be no less than established for specific types of buildings and structures.

In addition, if necessary, calculations should be made for thermal conductivity, sound insulation, biological protection and other parameters.

6.1.3 Calculation of concrete and reinforced concrete structures (linear, planar, spatial, massive) according to the limit states of the first and second groups is carried out according to stresses, forces, deformations and displacements calculated from external influences in structures and systems of buildings and structures formed by them, taking into account physical nonlinearity (inelastic deformations of concrete and reinforcement), possible formation of cracks and, in necessary cases, anisotropy, accumulation of damage and geometric nonlinearity (the effect of deformations on changes in forces in structures).

Physical nonlinearity and anisotropy should be taken into account in the constitutive relationships connecting stresses and strains (or forces and displacements), as well as in the conditions of strength and crack resistance of the material.

In statically indeterminate structures, it is necessary to take into account the redistribution of forces in the elements of the system due to the formation of cracks and the development of inelastic deformations in concrete and reinforcement up to the occurrence of a limit state in the element. In the absence of calculation methods that take into account the inelastic properties of reinforced concrete, or data on the inelastic operation of reinforced concrete elements, it is allowed to determine forces and stresses in statically indeterminate structures and systems under the assumption of elastic operation of reinforced concrete elements. In this case, it is recommended to take into account the influence of physical nonlinearity by adjusting the results of linear calculations based on data from experimental studies, nonlinear modeling, calculation results of similar objects and expert assessments.

When calculating structures for strength, deformation, formation and opening of cracks based on the finite element method, the conditions of strength and crack resistance for all finite elements making up the structure, as well as the conditions for the occurrence of excessive movements of the structure, must be checked. When assessing the limit state for strength, it is permissible to assume that individual finite elements are destroyed if this does not entail progressive destruction of the building or structure and, after the load under consideration has expired, the serviceability of the building or structure is maintained or can be restored.

Determination of ultimate forces and deformations in concrete and reinforced concrete structures should be made on the basis of design schemes (models) that most closely correspond to the real physical nature of the operation of structures and materials in the limit state under consideration.

The bearing capacity of reinforced concrete structures capable of undergoing sufficient plastic deformations (in particular, when using reinforcement with a physical yield strength) can be determined by the limit equilibrium method.

6.1.4 When calculating concrete and reinforced concrete structures based on limit states, various design situations should be considered in accordance with GOST 27751.

6.1.5 Calculations of concrete and reinforced concrete structures should be made for all types of loads that meet the functional purpose of buildings and structures, taking into account the influence of the environment (climatic influences and water - for structures surrounded by water), and, if necessary, taking into account the effects of fire, technological temperature and humidity influences and influences of aggressive chemical environments.

6.1.6. Calculations of concrete and reinforced concrete structures are carried out on the action of bending moments, longitudinal forces, transverse forces and torques, as well as on the local action of the load.

6.1.7. When calculating concrete and reinforced concrete structures, one should take into account the peculiarities of the properties of various types of concrete and reinforcement, the influence on them of the nature of the load and the environment, methods of reinforcement, the compatibility of the work of reinforcement and concrete (in the presence and absence of adhesion of reinforcement to concrete), the technology for manufacturing structural types of reinforced concrete elements buildings and structures.

Calculation of prestressed structures should be carried out taking into account the initial (preliminary) stresses and deformations in reinforcement and concrete, losses of prestress and the characteristics of the transfer of prestress to concrete.

Calculation of prefabricated monolithic and steel-reinforced concrete structures should be carried out taking into account the initial stresses and deformations received by prefabricated reinforced concrete or steel load-bearing elements from the action of loads when laying monolithic concrete until it gains strength and ensures joint work with precast reinforced concrete or steel load-bearing elements. When calculating prefabricated monolithic and steel-reinforced concrete structures, the strength of the contact seams of the interface of prefabricated reinforced concrete and steel load-bearing elements with monolithic concrete must be ensured, carried out due to friction, adhesion along the contact of materials or by installing keyed connections, reinforcement outlets and special anchor devices.

In monolithic structures, the strength of the structure must be ensured, taking into account the working joints of concreting.

When calculating prefabricated structures, the strength of the nodal and butt joints of prefabricated elements must be ensured, carried out by connecting steel embedded parts, reinforcement outlets and embedding with concrete.

Calculation of dispersed-reinforced structures (fiber-reinforced concrete, reinforced cement) should be made taking into account the characteristics of dispersed-reinforced concrete, dispersed reinforcement and the operating features of dispersed-reinforced structures.

6.1.8 When calculating flat and spatial structures subjected to force influences in two mutually perpendicular directions, individual flat or spatial small characteristic elements separated from the structure with forces acting on the lateral sides of the element are considered. If there are cracks, these forces are determined taking into account the location of the cracks, the stiffness of the reinforcement (axial and tangential), the stiffness of concrete (between cracks and in cracks) and other features. In the absence of cracks, the forces are determined as for a solid body.

In the presence of cracks, it is allowed to determine the forces under the assumption of elastic operation of the reinforced concrete element.

Calculation of elements should be carried out along the most dangerous sections located at an angle relative to the direction of the forces acting on the element, based on calculation models that take into account the work of tensile reinforcement in a crack and the work of concrete between cracks under plane stress conditions.

Calculation of flat and spatial structures can be carried out for the structure as a whole based on the limit equilibrium method, including taking into account the deformed state at the time of destruction, as well as using simplified calculation models.

6.1.9 When calculating massive structures subjected to force influences in three mutually perpendicular directions, individual small volumetric characteristic elements isolated from the structure with forces acting along the edges of the element are considered. In this case, the forces should be determined on the basis of premises similar to those adopted for planar elements (see 6.1.8).

Calculation of elements should be carried out along the most dangerous sections located at an angle relative to the direction of the forces acting on the element, based on calculation models that take into account the operation of concrete and reinforcement under volumetric stress conditions.

6.1.10 For structures of complex configuration (for example, spatial), in addition to calculation methods for assessing bearing capacity, crack resistance and deformability, the results of testing physical models can also be used.

6.2 Strength calculation of concrete and reinforced concrete elements

6.2.1. Calculation of concrete and reinforced concrete elements for strength is carried out:

For normal sections (under the action of bending moments and longitudinal forces) according to a nonlinear deformation model, and for elements with simple configurations - according to ultimate forces;

By inclined sections (under the action of transverse forces), by spatial sections (under the action of torques), by the local action of a load (local compression, punching) - by ultimate forces.

Calculation of the strength of short reinforced concrete elements (short consoles and other elements) is carried out on the basis of a frame-rod model.

6.2.2 Calculation of the strength of concrete and reinforced concrete elements based on ultimate forces is made from the condition under which the force F F ult, which can be perceived by an element in this section

F £ F ult.(6.1)

Strength calculation of concrete elements

6.2.3 Concrete elements, depending on their operating conditions and the requirements placed on them, should be calculated using normal sections according to ultimate forces without taking into account (6.2.4) or taking into account (6.2.5) the resistance of concrete in the tensile zone.

6.2.4 Without taking into account the resistance of concrete in the tensile zone, calculations are made of eccentrically compressed concrete elements at eccentricity values of the longitudinal force not exceeding 0.9 of the distance from the center of gravity of the section to the most compressed fiber. In this case, the maximum force that can be absorbed by the element is determined by the calculated compressive resistance of concrete Rb, uniformly distributed over the conditional compressed zone of the section with the center of gravity coinciding with the point of application of the longitudinal force.

For massive concrete structures of hydraulic structures, a triangular stress diagram should be taken in the compressed zone that does not exceed the calculated value of the concrete compressive resistance Rb. In this case, the eccentricity of the longitudinal force relative to the center of gravity of the section should not exceed 0.65 of the distance from the center of gravity to the most compressed concrete fiber.

6.2.5 Taking into account the resistance of concrete in the tensile zone, calculations are made of eccentrically compressed concrete elements with an eccentricity of longitudinal force greater than those specified in 6.2.4, bending concrete elements (which are allowed for use), as well as eccentrically compressed elements with an eccentricity of longitudinal force specified in 6.2.4, but in which, according to operating conditions, the formation of cracks is not allowed. In this case, the maximum force that can be absorbed by the section of the element is determined as for an elastic body at maximum tensile stresses equal to the calculated value of the tensile resistance of concrete R bt.

6.2.6 When calculating eccentrically compressed concrete elements, the influence of longitudinal bending and random eccentricities should be taken into account.

Calculation of reinforced concrete elements based on the strength of normal sections

6.2.7 Calculation of reinforced concrete elements based on ultimate forces should be carried out by determining the maximum forces that can be absorbed by concrete and reinforcement in a normal section, from the following provisions:

The tensile strength of concrete is assumed to be zero;

The resistance of concrete to compression is represented by stresses equal to the calculated resistance of concrete to compression and uniformly distributed over the conditional compressed zone of concrete;

Tensile and compressive stresses in reinforcement are assumed to be no more than the calculated resistance to tension and compression, respectively.

6.2.8 Calculation of reinforced concrete elements using a nonlinear deformation model is carried out on the basis of state diagrams of concrete and reinforcement based on the hypothesis of plane sections. The criterion for the strength of normal sections is the achievement of maximum relative deformations in concrete or reinforcement.

6.2.9 When calculating eccentrically compressed elements, random eccentricity and the influence of longitudinal bending should be taken into account.

Calculation of reinforced concrete elements based on the strength of inclined sections

6.2.10 Calculation of reinforced concrete elements based on the strength of inclined sections is carried out: along an inclined section for the action of a transverse force, along an inclined section for the action of a bending moment, and along a strip between inclined sections for the action of a transverse force.

6.2.11 When calculating a reinforced concrete element based on the strength of an inclined section under the action of a transverse force, the maximum transverse force that can be absorbed by an element in an inclined section should be determined as the sum of the maximum transverse forces perceived by concrete in an inclined section and transverse reinforcement crossing the inclined section.

6.2.12 When calculating a reinforced concrete element based on the strength of an inclined section under the action of a bending moment, the limiting moment that can be absorbed by the element in the inclined section should be determined as the sum of the limiting moments perceived by the longitudinal and transverse reinforcement crossing the inclined section, relative to the axis passing through the point of application of the resultant forces in compressed zone.

6.2.13 When calculating a reinforced concrete element along a strip between inclined sections under the action of a transverse force, the maximum transverse force that can be absorbed by the element should be determined based on the strength of the inclined concrete strip, which is under the influence of compressive forces along the strip and tensile forces from transverse reinforcement crossing the inclined strip.

Calculation of reinforced concrete elements based on the strength of spatial sections

6.2.14 When calculating reinforced concrete elements based on the strength of spatial sections, the maximum torque that can be absorbed by the element should be determined as the sum of the maximum torques perceived by longitudinal and transverse reinforcement located at each edge of the element and intersecting the spatial section. In addition, it is necessary to calculate the strength of a reinforced concrete element using a concrete strip located between the spatial sections and under the influence of compressive forces along the strip and tensile forces from transverse reinforcement crossing the strip.

Calculation of reinforced concrete elements for local load action

6.2.15 When calculating reinforced concrete elements for local compression, the maximum compressive force that can be absorbed by the element should be determined based on the resistance of the concrete under the volumetric stress state created by the surrounding concrete and indirect reinforcement, if installed.

6.2.16 Punching calculations are carried out for flat reinforced concrete elements (slabs) under the action of concentrated forces and moments in the punching zone. The maximum force that can be absorbed by a reinforced concrete element during punching should be determined as the sum of the maximum forces perceived by concrete and transverse reinforcement located in the punching zone.

6.3 Calculation of reinforced concrete elements for the formation of cracks

6.3.1 Calculation of reinforced concrete elements for the formation of normal cracks is carried out using limiting forces or using a nonlinear deformation model. Calculations for the formation of inclined cracks are made using maximum forces.

6.3.2 Calculation of the formation of cracks in reinforced concrete elements based on ultimate forces is carried out from the condition according to which the force F from external loads and influences in the section under consideration should not exceed the maximum force Fcrc, which can be absorbed by a reinforced concrete element when cracks form

F £ Fcrc,ult.(6.2)

6.3.3 The maximum force perceived by a reinforced concrete element during the formation of normal cracks should be determined based on the calculation of the reinforced concrete element as a solid body, taking into account elastic deformations in reinforcement and inelastic deformations in tensile and compressed concrete at maximum normal tensile stresses in concrete equal to the calculated values of concrete tensile strength Rbr.

6.3.4 Calculation of reinforced concrete elements for the formation of normal cracks using a nonlinear deformation model is carried out on the basis of state diagrams of reinforcement, tensile and compressed concrete and the hypothesis of plane sections. The criterion for the formation of cracks is the achievement of maximum relative deformations in tensile concrete.

6.3.5 The maximum force that can be absorbed by a reinforced concrete element during the formation of inclined cracks should be determined based on the calculation of the reinforced concrete element as a continuous elastic body and the concrete strength criterion in a plane stress state “compression-tension”.

6.4 Calculation of reinforced concrete elements based on crack opening

6.4.1 Calculation of reinforced concrete elements is carried out based on the opening of various types of cracks in cases where a design test for the formation of cracks shows that cracks are formed.

6.4.2 Crack opening calculations are made based on the condition that the crack opening width due to external load Acrc should not exceed the maximum permissible crack opening width a crc ult

a crc £ acrc,ult. (6.3)

6.4.3 Calculations of reinforced concrete elements should be made based on long-term and short-term opening of normal and inclined cracks.

The width of continuous crack opening is determined by the formula

a crc = a crc 1 , (6.4)

and short crack opening - according to the formula

a crc = a crc 1 + a crc 2 - a crc 3 , (6.5)

Where a crc 1 - crack opening width due to prolonged action of constant and temporary long-term loads;

a crc 2 - width of crack opening due to short-term action of constant and temporary (long-term and short-term) loads;

a crc 3 - crack opening width due to short-term action of constant and temporary long-term loads.

6.4.4 The opening width of normal cracks is determined as the product of the average relative deformations of the reinforcement in the area between the cracks and the length of this area. The average relative deformations of the reinforcement between cracks are determined taking into account the work of tensile concrete between the cracks. Relative deformations of reinforcement in a crack are determined from a conditionally elastic calculation of a reinforced concrete element with cracks using the reduced deformation modulus of compressed concrete, established taking into account the influence of inelastic deformations of concrete in the compressed zone, or using a nonlinear deformation model. The distance between cracks is determined from the condition that the difference in forces in the longitudinal reinforcement in the section with a crack and between the cracks should be absorbed by the adhesion forces of the reinforcement to the concrete along the length of this section.

The opening width of normal cracks should be determined taking into account the nature of the load (repetition, duration, etc.) and the type of reinforcement profile.

6.4.5 The maximum permissible crack opening width should be set based on aesthetic considerations, requirements for the permeability of structures, as well as depending on the duration of the load, the type of reinforcing steel and its tendency to develop corrosion in the crack.

In this case, the maximum permissible value of the crack opening width is a crc , ult should take no more than:

a) from the condition of safety of the reinforcement:

0.3 mm - with prolonged crack opening;

0.4 mm - with short-term crack opening;

b) from the condition of limiting the permeability of structures:

0.2 mm - with prolonged crack opening;

0.3 mm - with short-term crack opening.

For massive hydraulic structures, the maximum permissible values of crack opening width are established according to the relevant regulatory documents, depending on the operating conditions of the structures and other factors, but not more than 0.5 mm.

6.5 Calculation of reinforced concrete elements based on deformations

6.5.1 Calculation of reinforced concrete elements by deformations is carried out from the condition according to which deflections or movements of structures f from the action of external load should not exceed the maximum permissible values of deflections or movements f ult

f £ f ult. (6.6)

6.5.2 Deflections or movements of reinforced concrete structures are determined according to the general rules of structural mechanics, depending on the bending, shear and axial deformation (rigidity) characteristics of the reinforced concrete element in sections along its length (curvature, shear angles, etc.).

6.5.3 In cases where the deflections of reinforced concrete elements mainly depend on flexural deformations, the values of the deflections are determined by the stiffness or curvature of the elements.

The rigidity of the section of a reinforced concrete element under consideration is determined according to the general rules of material strength: for a section without cracks - as for a conditionally elastic solid element, and for a section with cracks - as for a conditionally elastic element with cracks (assuming a linear relationship between stresses and deformations). The influence of inelastic deformations of concrete is taken into account using the reduced deformation modulus of concrete, and the influence of the work of tensile concrete between cracks is taken into account using the reduced deformation modulus of reinforcement.

The curvature of a reinforced concrete element is determined as the quotient of the bending moment divided by the bending stiffness of the reinforced concrete section.

Calculation of deformations of reinforced concrete structures taking into account cracks is carried out in cases where a design test for the formation of cracks shows that cracks are formed. Otherwise, the deformations are calculated as for a reinforced concrete element without cracks.

The curvature and longitudinal deformations of a reinforced concrete element are also determined using a nonlinear deformation model based on the equilibrium equations of external and internal forces acting in the normal section of the element, the hypothesis of plane sections, state diagrams of concrete and reinforcement, and average deformations of reinforcement between cracks.

6.5.4 Calculation of deformations of reinforced concrete elements should be made taking into account the duration of the loads established by the relevant regulatory documents.

The curvature of elements under constant and long-term loads should be determined using the formula

and curvature under the action of constant, long-term and short-term loads - according to the formula

where is the curvature of the element due to the prolonged action of constant and temporary long-term loads;

Curvature of an element from short-term action of constant and temporary (long-term and short-term) loads;

Curvature of an element due to short-term action of constant and temporary long-term loads.

6.5.5 Maximum permissible deflections f ult determined according to the relevant regulatory documents (SNiP 2.01.07). Under the action of constant and temporary long-term and short-term loads, the deflection of reinforced concrete elements in all cases should not exceed 1/150 of the span and 1/75 of the cantilever overhang.

7 DESIGN REQUIREMENTS

7.1 General provisions

7.1.1 To ensure the safety and serviceability of concrete and reinforced concrete structures, in addition to calculation requirements, design requirements for geometric dimensions and reinforcement must also be met.

Design requirements are established for cases where:

by calculation it is not possible to accurately and definitely fully guarantee the resistance of the structure to external loads and influences;

design requirements determine the boundary conditions within which the accepted design provisions can be used;

design requirements ensure the implementation of the manufacturing technology of concrete and reinforced concrete structures.

7.2 Requirements for geometric dimensions

The geometric dimensions of concrete and reinforced concrete structures must be no less than the values ensuring:

The ability to place reinforcement, anchor it and work together with concrete, taking into account the requirements of 7.3.3-7.3.11;

Limitation of flexibility of compressed elements;

Required quality indicators of concrete in a structure (GOST 4.250).

7.3 Reinforcement requirements

Protective layer of concrete

7.3.1 The protective layer of concrete must provide:

Anchoring of reinforcement in concrete and the possibility of making joints of reinforcing elements;

Safety of fittings from environmental influences (including in the presence of aggressive influences);

Fire resistance and fire safety of structures.

7.3.2 The thickness of the protective layer of concrete should be taken based on the requirements of 7.3.1, taking into account the role of reinforcement in structures (working or structural), type of structures (columns, slabs, beams, foundation elements, walls, etc.), diameter and type of reinforcement.

The thickness of the protective layer of concrete for reinforcement is taken to be no less than the diameter of the reinforcement and no less than 10 mm.

Minimum distance between reinforcement bars

7.3.3 The distance between the reinforcement bars should be no less than the value that ensures:

Combined work of reinforcement with concrete;

Possibility of anchoring and joining of reinforcement;

Possibility of high-quality concreting of the structure.

7.3.4 The minimum clear distance between reinforcement bars should be taken depending on the diameter of the reinforcement, the size of the coarse concrete aggregate, the location of the reinforcement in the element in relation to the direction of concreting, the method of laying and compacting concrete.

The distance between the reinforcement bars should be taken to be no less than the diameter of the reinforcement and no less than 25 mm.

In cramped conditions, it is allowed to place reinforcement bars in groups-bundles (without a gap between the bars). In this case, the clear distance between the beams should be taken to be no less than the given diameter of the conditional rod, the area of which is equal to the cross-sectional area of the reinforcement beam.

Longitudinal reinforcement

7.3.5 The relative content of the design longitudinal reinforcement in a reinforced concrete element (the ratio of the cross-sectional area of the reinforcement to the effective cross-sectional area of the element) should be taken to be no less than the value at which the element can be considered and calculated as reinforced concrete.

The minimum relative content of working longitudinal reinforcement in a reinforced concrete element is determined depending on the nature of the reinforcement (compressed, tensile), the nature of the element (bending, eccentrically compressed, eccentrically tensioned) and the flexibility of the eccentrically compressed element, but not less than 0.1%. For massive hydraulic structures, lower values of the relative content of reinforcement are established according to special regulatory documents.

7.3.6 The distance between the rods of longitudinal working reinforcement should be taken taking into account the type of reinforced concrete element (columns, beams, slabs, walls), the width and height of the element’s section and not more than the value that ensures the effective involvement of concrete in the work, uniform distribution of stresses and deformations along the width of the element’s section, as well as limiting the width of cracks between reinforcement bars. In this case, the distance between the rods of the longitudinal working reinforcement should be taken no more than twice the height of the element’s section and no more than 400 mm, and in linear eccentrically compressed elements in the direction of the bending plane - no more than 500 mm. For massive hydraulic structures, large distances between rods are established according to special regulatory documents.

Transverse reinforcement

7.3.7 In reinforced concrete elements in which the transverse force cannot be absorbed by concrete alone, according to calculations, transverse reinforcement should be installed with a step of no more than the value that ensures the inclusion of transverse reinforcement in the operation during the formation and development of inclined cracks. In this case, the pitch of transverse reinforcement should be no more than half the working height of the element’s section and no more than 300 mm.

7.3.8 In reinforced concrete elements containing design compressed longitudinal reinforcement, transverse reinforcement should be installed with a pitch of no more than a value that ensures the longitudinal compressed reinforcement is secured against buckling. In this case, the pitch of the transverse reinforcement should be no more than fifteen diameters of the compressed longitudinal reinforcement and no more than 500 mm, and the design of the transverse reinforcement should ensure that there is no buckling of the longitudinal reinforcement in any direction.

Anchoring and connections of reinforcement

7.3.9 In reinforced concrete structures, reinforcement anchoring must be provided to ensure that the design forces in the reinforcement in the section under consideration are absorbed. The length of the anchorage is determined from the condition according to which the force acting in the reinforcement must be absorbed by the adhesion forces of the reinforcement with concrete acting along the length of the anchorage, and by the resistance forces of the anchoring devices, depending on the diameter and profile of the reinforcement, the tensile strength of concrete, and the thickness of the protective layer of concrete , type of anchoring devices (bending of the rod, welding of transverse rods), transverse reinforcement in the anchoring zone, the nature of the force in the reinforcement (compressive or tensile) and the stress state of the concrete along the length of the anchoring.

7.3.10 Anchoring of transverse reinforcement should be carried out by bending it and wrapping it around the longitudinal reinforcement or by welding to the longitudinal reinforcement. In this case, the diameter of the longitudinal reinforcement must be at least half the diameter of the transverse reinforcement.

7.3.11 An overlap connection of reinforcement (without welding) must be made to a length that ensures the transfer of design forces from one joined rod to another. The length of the overlap is determined by the base length of the anchorage with additional consideration of the relative number of bars joined in one place, transverse reinforcement in the lap joint area, the distance between the joined rods and between butt joints.

7.3.12 Welded connections of reinforcement should be made in accordance with the relevant regulatory documents (GOST 14098, GOST 10922).

7.4 Protection of structures from the adverse effects of environmental influences

7.4.1 In cases where the required durability of structures operating under conditions of adverse environmental influences (aggressive influences) cannot be ensured by the corrosion resistance of the structure itself, additional protection of the structure surfaces must be provided, carried out according to the instructions of SNiP 2.03.11 (treatment of the surface layer of concrete with resistant to aggressive influences of materials, application of coatings resistant to aggressive influences on the surface of the structure, etc.).

8 REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND OPERATION OF CONCRETE AND REINFORCED CONCRETE STRUCTURES

8.1 Concrete

8.1.1 The composition of the concrete mixture is selected in order to obtain concrete in structures that meets the technical indicators established in Section 5 and adopted in the project.

When selecting the composition of concrete, the concrete indicator that determines the type of concrete and the purpose of the structure should be taken as the basis. At the same time, other concrete quality indicators established by the project must be ensured.

The design and selection of the composition of the concrete mixture according to the required concrete strength should be carried out in accordance with the relevant regulatory documents (GOST 27006, GOST 26633, etc.).

When selecting the composition of a concrete mixture, the required quality indicators must be ensured (workability, shelf life, non-segregation, air content and other indicators).

The properties of the selected concrete mixture must correspond to the technology for the production of concrete work, including the terms and conditions of concrete hardening, methods, modes of preparation and transportation of the concrete mixture and other features of the technological process (GOST 7473, GOST 10181).

The composition of the concrete mixture should be selected based on the characteristics of the materials used for its preparation, including binders, fillers, water and effective additives (modifiers) (GOST 30515, GOST 23732, GOST 8267, GOST 8736, GOST 24211).

When selecting the composition of a concrete mixture, materials should be used taking into account their environmental friendliness (limitations on the content of radionuclides, radon, toxicity, etc.).

The calculation of the main parameters of the composition of the concrete mixture is carried out using dependencies established experimentally.

The composition of fiber-reinforced concrete should be selected in accordance with the above requirements, taking into account the type and properties of the reinforcing fibers.

8.1.2 When preparing a concrete mixture, the necessary accuracy of dosage of the materials included in the concrete mixture and the sequence of their loading must be ensured (SNiP 3.03.01).

Mixing the concrete mixture should be done in such a way as to ensure uniform distribution of the components throughout the entire volume of the mixture. The duration of mixing is taken in accordance with the instructions of the manufacturers of concrete mixing plants (plants) or is established experimentally.

8.1.3 Transportation of the concrete mixture should be carried out in ways and means that ensure the preservation of its properties and prevent its separation, as well as contamination with foreign materials. It is allowed to restore certain quality indicators of the concrete mixture at the placement site through the introduction of chemical additives or the use of technological methods, provided that all other required quality indicators are met.

8.1.4 Laying and compaction of concrete should be carried out in such a way that it is possible to guarantee sufficient homogeneity and density of concrete in structures that meet the requirements specified for the building structure in question (SNiP 3.03.01).

The molding methods and modes used must ensure the specified density and uniformity and are established taking into account the quality indicators of the concrete mixture, the type of structure and product, and specific geotechnical and production conditions.

The order of concreting should be established, providing for the location of concreting seams, taking into account the construction technology of the structure and its design features. In this case, the necessary contact strength of the concrete surfaces in the concreting seam must be ensured, as well as the strength of the structure taking into account the presence of concreting seams.

When laying a concrete mixture at low positive and negative or increased positive temperatures, special measures must be taken to ensure the required quality of concrete.

8.1.5 Hardening of concrete should be ensured without or with the use of accelerating technological influences (using heat and moisture treatment at normal or increased pressure).

In concrete during the hardening process, the design temperature and humidity conditions should be maintained. If necessary, to create conditions that ensure an increase in the strength of concrete and a reduction in shrinkage phenomena, special protective measures should be used. In the technological process of heat treatment of products, measures must be taken to reduce temperature differences and mutual movements between the formwork and concrete.

In massive monolithic structures, measures should be taken to reduce the influence of temperature and humidity stress fields associated with exotherm during concrete hardening on the operation of structures.

8.2 Fittings

8.2.1 The reinforcement used to reinforce structures must comply with the design and the requirements of the relevant standards. The fittings must be marked and have appropriate certificates certifying their quality.

The conditions for storing reinforcement and its transportation must exclude mechanical damage or plastic deformation, contamination that impairs adhesion to concrete, and corrosion damage.

8.2.2 Installation of knitted reinforcement in formwork forms should be carried out in accordance with the project. In this case, reliable fixation of the position of the reinforcing bars must be provided using special measures, ensuring that the reinforcement cannot be displaced during its installation and concreting of the structure.

Deviations from the design position of the reinforcement during its installation should not exceed the permissible values established by SNiP 3.03.01.

8.2.3. Welded reinforcement products (mesh, frames) should be manufactured using resistance spot welding or other methods that ensure the required strength of the welded joint and do not allow a decrease in the strength of the reinforcement elements being connected (GOST 14098, GOST 10922).

Installation of welded reinforcement products in formwork forms should be carried out in accordance with the design. In this case, reliable fixation of the position of the reinforcement products must be provided using special measures to ensure that the reinforcement products cannot be displaced during installation and concreting.

Deviations from the design position of reinforcement products during their installation should not exceed the permissible values established by SNiP 3.03.01.

8.2.4 The bending of reinforcing bars should be carried out using special mandrels that provide the required values of the radius of curvature.

8.2.5 Welded joints of reinforcement are performed using contact, arc or bath welding. The welding method used must provide the necessary strength of the welded joint, as well as the strength and deformability of the sections of reinforcing bars adjacent to the welded joint.

8.2.6 Mechanical connections (joints) of the reinforcement should be made using pressed and threaded couplings. The strength of the mechanical connection of the tensile reinforcement should be the same as that of the joined bars.

8.2.7 When tensioning reinforcement on stops or hardened concrete, the controlled prestress values established in the project must be ensured within the permissible deviation values established by regulatory documents or special requirements.

When releasing the tension of the reinforcement, a smooth transfer of prestress to the concrete should be ensured.

8.3 Formwork

8.3.1 Formwork (formwork forms) must perform the following main functions: give the concrete the design shape of the structure, provide the required appearance of the outer surface of the concrete, support the structure until it gains formwork strength and, if necessary, serve as a stop when tensioning the reinforcement.

In the manufacture of structures, inventory and special, adjustable and mobile formwork are used (GOST 23478, GOST 25781).

Formwork and its supports should be designed and manufactured in such a way that they can withstand the loads arising during the work process, allow the structures to deform freely and ensure compliance with tolerances within the limits established for the given structure or structure.

The formwork and fastenings must comply with the accepted methods of laying and compacting the concrete mixture, the conditions of prestressing, concrete hardening and heat treatment.

Removable formwork should be designed and manufactured in such a way that the formwork can be removed without damaging the concrete.

Stripping of structures should be done after the concrete has reached its stripping strength.

Permanent formwork should be designed as an integral part of the structure.

8.4 Concrete and reinforced concrete structures

8.4.1 The production of concrete and reinforced concrete structures includes formwork, reinforcement and concrete work carried out in accordance with the instructions of subsections 8.1, 8.2 and 8.3.

Finished structures must meet the requirements of the project and regulatory documents (GOST 13015.0, GOST 4.250). Deviations in geometric dimensions must be within the tolerances established for this design.

8.4.2 In concrete and reinforced concrete structures, at the beginning of their operation, the actual strength of concrete should not be lower than the required concrete strength established in the project.

In prefabricated concrete and reinforced concrete structures, the tempering strength of concrete established by the project (the strength of concrete when the structure is sent to the consumer) must be ensured, and for prestressed structures, the transfer strength established by the project (the strength of concrete when the tension of the reinforcement is released).

In monolithic structures, the stripping strength of concrete must be ensured at the age established by the design (when removing the load-bearing formwork).

8.4.3 Lifting of structures should be carried out using special devices (mounting loops and other devices) provided for by the project. In this case, lifting conditions must be ensured that exclude destruction, loss of stability, overturning, swinging and rotation of the structure.

8.4.4 The conditions for transportation, warehousing and storage of structures must comply with the instructions given in the project. At the same time, the safety of the structure, concrete surfaces, reinforcement outlets and mounting loops from damage must be ensured.

8.4.5 The construction of buildings and structures from prefabricated elements should be carried out in accordance with the work project, which should provide for the sequence of installation of structures and measures that ensure the required accuracy of installation, spatial invariability of structures during their enlarged assembly and installation in the design position, stability of structures and parts buildings or structures in the process of construction, safe working conditions.

When constructing buildings and structures made of monolithic concrete, a sequence of concreting the structures, removing and rearranging the formwork should be provided to ensure the strength, crack resistance and rigidity of the structures during the construction process. In addition, measures should be taken (structural and technological, and, if necessary, calculations) that limit the formation and development of technological cracks.

Deviations of structures from the design position must not exceed the permissible values established for the corresponding structures (columns, beams, slabs) of buildings and structures (SNiP 3.03.01).

8.4.6 Structures should be maintained in such a way that they fulfill their purpose, as provided for in the project, for the entire specified service life of the building or structure. It is necessary to observe the operating regime of concrete and reinforced concrete structures of buildings and structures, excluding a decrease in their load-bearing capacity, serviceability and durability due to gross violations of standardized operating conditions (overloading of structures, failure to comply with the terms of scheduled maintenance, increased environmental aggressiveness, etc.). If damage to the structure is discovered during operation, which may reduce its safety and interfere with its normal functioning, the measures provided for in section 9 should be taken.

8.5 Quality control

8.5.1 Quality control of structures should establish compliance of the technical indicators of structures (geometric dimensions, strength indicators of concrete and reinforcement, strength, crack resistance and deformability of the structure) during their manufacture, construction and operation, as well as the parameters of technological production modes with the indicators specified in the project, regulatory documents and in technological documentation (SNiP 12-01, GOST 4.250).

Quality control methods (control rules, test methods) are regulated by relevant standards and technical specifications (SNiP 3.03.01, GOST 13015.1, GOST 8829, GOST 17625, GOST 22904, GOST 23858).

8.5.2 To ensure the requirements for concrete and reinforced concrete structures, product quality control should be carried out, including input, operational, acceptance and operational control.

8.5.3 Concrete strength control should be carried out, as a rule, based on the results of testing specially made or selected control samples from the structure (GOST 10180, GOST 28570).

For monolithic structures, in addition, control of the strength of concrete should be carried out based on the results of testing control samples made at the site of laying the concrete mixture and stored under conditions identical to the hardening of concrete in the structure, or by non-destructive methods (GOST 18105, GOST 22690, GOST 17624).

Strength control should be carried out using a statistical method, taking into account the actual heterogeneity of concrete strength, characterized by the value of the coefficient of variation of concrete strength at a concrete manufacturer or at a construction site, as well as with non-destructive methods for monitoring the strength of concrete in structures.

It is allowed to use non-statistical control methods based on the test results of control samples with a limited volume of controlled structures, at the initial stage of their control, with additional selective control at the construction site of monolithic structures, as well as during control by non-destructive methods. In this case, the class of concrete is established taking into account the instructions of 9.3.4.

8.5.4 Control of frost resistance, water resistance and density of concrete should be carried out in accordance with the requirements of GOST 10060.0, GOST 12730.5, GOST 12730.1, GOST 12730.0, GOST 27005.

8.5.5 Control of quality indicators of reinforcement (incoming inspection) should be carried out in accordance with the requirements of standards for reinforcement and norms for drawing up certificates for assessing the quality of reinforced concrete products.

Quality control of welding work is carried out in accordance with SNiP 3.03.01, GOST 10922, GOST 23858.

8.5.6 Assessment of the suitability of structures in terms of strength, crack resistance and deformability (serviceability) should be carried out according to the instructions of GOST 8829 by test loading the structure with a control load or by selective loading testing to failure of individual prefabricated products taken from a batch of similar structures. The suitability of a structure can also be assessed based on the results of monitoring a set of single indicators (for prefabricated and monolithic structures) characterizing the strength of concrete, the thickness of the protective layer, the geometric dimensions of sections and structures, the location of reinforcement and the strength of welded joints, the diameter and mechanical properties of reinforcement, and main dimensions reinforcement products and the value of reinforcement tension obtained in the process of incoming, operational and acceptance control.

8.5.7 Acceptance of concrete and reinforced concrete structures after their construction should be carried out by establishing compliance of the completed structure with the project (SNiP 3.03.01).

9 REQUIREMENTS FOR RESTORATION AND STRENGTHENING OF REINFORCED CONCRETE STRUCTURES

9.1 General provisions

Restoration and strengthening of reinforced concrete structures should be carried out on the basis of the results of their full-scale examination, verification calculation, calculation and design of reinforced structures.

9.2 Field surveys of structures

Through field examinations, depending on the task, the following must be established: the condition of the structure, geometric dimensions of structures, reinforcement of structures, concrete strength, type and class of reinforcement and its condition, deflections of structures, width of cracks, their length and location, size and nature of defects and damage , loads, static diagram of structures.

9.3 Verification calculations of structures

9.3.1 Verification calculations of existing structures should be carried out when the loads acting on them, operating conditions and space-planning solutions change, as well as when serious defects and damage are detected in the structures.

Based on verification calculations, the suitability of structures for operation, the need to strengthen them or reduce the operational load, or the complete unsuitability of structures are determined.

9.3.2 Verification calculations must be made on the basis of design materials, data on the manufacture and construction of structures, as well as the results of field surveys.

When carrying out verification calculations, design schemes should be taken taking into account the established actual geometric dimensions, the actual connection and interaction of structures and structural elements, and identified deviations during installation.

9.3.3 Verification calculations should be made based on load-bearing capacity, deformation and crack resistance. It is allowed not to carry out verification calculations for serviceability if the displacements and width of cracks in existing structures at maximum actual loads do not exceed the permissible values, and the forces in the sections of elements from possible loads do not exceed the values of forces from actual loads.

9.3.4 The calculated values of concrete characteristics are taken depending on the class of concrete specified in the project, or the conditional class of concrete, determined using conversion factors that provide equivalent strength based on the actual average strength of concrete obtained from testing concrete using non-destructive methods or from testing samples taken from the structure.

9.3.5 The calculated values of the characteristics of the reinforcement are taken depending on the class of reinforcement specified in the project, or the conditional class of reinforcement determined using conversion factors that provide equivalent strength based on the actual values of the average strength of the reinforcement obtained from testing data on reinforcement samples selected from the structures being examined.

In the absence of design data and the impossibility of sampling, it is allowed to set the class of reinforcement according to the type of reinforcement profile, and the calculated resistances are taken to be 20% lower than the corresponding values of the current regulatory documents that meet this class.

9.3.6 When carrying out verification calculations, defects and damage to the structure identified during field inspections must be taken into account: reduction in strength, local damage or destruction of concrete; breakage of reinforcement, corrosion of reinforcement, violation of anchorage and adhesion of reinforcement to concrete; dangerous formation and opening of cracks; constructive deviations from the design in individual structural elements and their connections.

9.3.7 Structures that do not meet the requirements of verification calculations for load-bearing capacity and serviceability must be strengthened or their operational load must be reduced.

For structures that do not meet the requirements of verification calculations for serviceability, it is allowed not to provide for strengthening or reducing the load if the actual deflections exceed the permissible values, but do not interfere with normal operation, and also if the actual opening of cracks exceeds the permissible values, but does not create a danger of destruction.

9.4 Strengthening reinforced concrete structures

9.4.1 Strengthening of reinforced concrete structures is carried out using steel elements, concrete and reinforced concrete, reinforcement and polymer materials.

9.4.2 When strengthening reinforced concrete structures, the load-bearing capacity of both the reinforcement elements and the reinforced structure should be taken into account. To do this, it must be ensured that reinforcing elements are included in the work and that they work together with the structure being reinforced. For heavily damaged structures, the load-bearing capacity of the reinforced structure is not taken into account.

When sealing cracks with an opening width greater than permissible and other concrete defects, it is necessary to ensure that the sections of structures that have undergone restoration are equal in strength to the base concrete.

9.4.3 The calculated values of the characteristics of reinforcement materials are taken according to current regulatory documents.

The calculated values of the characteristics of the materials of the reinforced structure are taken based on the design data, taking into account the results of the examination in accordance with the rules adopted for verification calculations.

9.4.4 The calculation of the reinforced concrete structure to be strengthened should be carried out according to the general rules for the calculation of reinforced concrete structures, taking into account the stress-strain state of the structure obtained before strengthening.

APPENDIX A

Information

SNiP 2.01.07-85*	Loads and impacts
SNiP 2.02.01-83*	Foundations of buildings and structures
SNiP 2.03.11-85	Protection of building structures from corrosion
SNiP 2.05.03-84*	Bridges and pipes
SNiP 2.06.04-82*	Loads and impacts on hydraulic structures (wave, ice and from ships)
SNiP 2.06.06-85	Concrete and reinforced concrete dams
SNiP 3.03.01-87	Load-bearing and enclosing structures
	Organization of construction
SNiP 21-01-97*	Fire safety of buildings and structures
SNiP 23-01-99*	Construction climatology
SNiP 02/23/2003	Thermal protection of buildings
	Railway and road tunnels
	Hydraulic structures. Basic provisions
SNiP II-7-81*	Construction in seismic areas
SNiP II-23-81*	Steel structures
	SPKP. Construction. Concrete. Nomenclature of indicators
	SPKP. Construction. Concrete and reinforced concrete products and structures. Nomenclature of indicators
GOST 5781-82	Hot rolled steel for reinforcement of reinforced concrete structures. Specifications
GOST 6727-80	Cold-drawn low-carbon steel wire for reinforcing reinforced concrete structures. Specifications
GOST 7473-94	Concrete mixtures. Specifications
GOST 8267-93	Crushed stone and gravel from dense rocks for construction work. Specifications
GOST 8736-93	Sand for construction work. Specifications
	Factory-made reinforced concrete and concrete building products. Load test methods. Rules for assessing strength, stiffness and crack resistance
	Concrete. Methods for determining frost resistance. General provisions
	Concrete. Methods for determining strength using control samples
	Concrete mixtures. Test methods
	Reinforcing steel thermomechanically strengthened for reinforced concrete structures. Specifications
	Welded reinforcement and embedded products, welded connections of reinforcement and embedded products of reinforced concrete structures. General technical conditions
GOST 12730.0-78	Concrete. General requirements for methods for determining density, porosity and water resistance
GOST 12730.1-78	Concrete. Methods for determining density
GOST 12730.5-84	Concrete. Methods for determining water resistance
GOST 13015.0-83	Prefabricated concrete and reinforced concrete structures and products. General technical requirements
GOST 13015.1-81	Prefabricated concrete and reinforced concrete structures and products. Acceptance
	Welded connections of reinforcement and embedded products of reinforced concrete structures. Types, design and dimensions
	Concrete. Ultrasonic method for determining strength
	Reinforced concrete structures and products. Radiation method for determining the thickness of the protective layer of concrete, the size and location of reinforcement
GOST 18105-86	Concrete. Strength control rules
GOST 20910-90	Heat-resistant concrete. Specifications
	Concrete. Determination of strength by mechanical methods of non-destructive testing
	Reinforced concrete structures. Magnetic method for determining the thickness of the protective layer of concrete and the location of reinforcement
	Formwork for the construction of monolithic concrete and reinforced concrete structures. Classification and general technical requirements
GOST 23732-79	Water for concrete and mortars. Specifications
	Welded butt and tee connections for reinforced concrete structures. Ultrasonic quality control methods. Acceptance rules
GOST 24211-91	Additives for concrete. General technical requirements
	Concrete. Classification and general technical requirements
	Silicate concrete is dense. Specifications
GOST 25246-82	Concrete is chemically resistant. Specifications
GOST 25485-89	Cellular concrete. Specifications
GOST 25781-83	Steel forms for the manufacture of reinforced concrete products. Specifications
	Concrete is lightweight. Specifications
GOST 26633-91	Concrete is heavy and fine-grained. Specifications
GOST 27005-86	Concrete is light and cellular. Average Density Control Rules
GOST 27006-86	Concrete. Squad selection rules
	Reliability of building structures and foundations. Basic provisions for calculation
GOST 28570-90	Concrete. Methods for determining strength using samples taken from structures
	Cements. General technical conditions
	Polystyrene concrete. Specifications
STO ASCHM 7-93	Rolled periodic profiles from reinforcing steel. Specifications

APPENDIX B

Information

TERMS AND DEFINITIONS

Concrete structures -	structures made of concrete without reinforcement or with reinforcement installed for structural reasons and not taken into account in the calculation, the design forces from all impacts in concrete structures must be absorbed by concrete.
Reinforced concrete structures -	structures made of concrete with working and structural reinforcement (reinforced concrete structures), the design forces from all impacts in reinforced concrete structures must be absorbed by concrete and working reinforcement.
Steel-reinforced concrete structures -	reinforced concrete structures, including steel elements other than reinforcing steel, working in conjunction with reinforced concrete elements.
Dispersion-reinforced structures (fiber-reinforced concrete, reinforced cement) -	reinforced concrete structures, including dispersed fibers or fine-mesh meshes made of thin steel wire.
Working fittings -	fittings installed according to calculation.
Structural fittings -	reinforcement installed without calculation for structural reasons.
Pre-stressed reinforcement -	reinforcement that receives initial (preliminary) stresses during the manufacturing process of structures before the application of external loads during the operation stage.
Anchoring reinforcement -	ensuring that the reinforcement accepts the forces acting on it by moving it to a certain length beyond the design cross-section or by installing special anchors at the ends.
Overlapping reinforcement joints -	connecting reinforcing bars along their length without welding by inserting the end of one reinforcing bar relative to the end of another.
Working section height -	the distance from the compressed edge of the element to the center of gravity of the tensile longitudinal reinforcement.
Protective layer of concrete -	the thickness of the concrete layer from the edge of the element to the nearest surface of the reinforcing bar.
Ultimate force-	the greatest force that can be absorbed by an element or its cross-section given the accepted characteristics of the materials.

APPENDIX B

Information

SAMPLE LIST OF CODES OF RULES DEVELOPED IN DEVELOPMENT OF SNiP 52-01-2003 “CONCRETE AND REINFORCED CONCRETE STRUCTURES. BASIC PROVISIONS"

1. Concrete and reinforced concrete structures without prestressing reinforcement.

2. Prestressed reinforced concrete structures.

3. Prefabricated monolithic structures.

4. Dispersed reinforced concrete structures.

5. Steel-reinforced concrete structures.

6. Self-stressed reinforced concrete structures.

7. Reconstruction, restoration and strengthening of concrete and reinforced concrete structures.

8. Concrete and reinforced concrete structures exposed to aggressive environments.

9. Concrete and reinforced concrete structures exposed to fire.

10. Concrete and reinforced concrete structures exposed to technological and climatic temperature and humidity influences.

11. Concrete and reinforced concrete structures subject to repeated and dynamic loads.

12. Concrete and reinforced concrete structures made of concrete with porous aggregates and porous structure.

13. Concrete and reinforced concrete structures made of fine-grained concrete.

14. Concrete and reinforced concrete structures made of high-strength concrete (class above B60).

15. Reinforced concrete frame buildings and structures.

16. Concrete and reinforced concrete frameless buildings and structures.

17. Spatial concrete and reinforced concrete structures.

Key words: requirements for concrete and reinforced concrete structures, standard and design values of the strength and deformation characteristics of concrete, requirements for reinforcement, calculation of concrete and reinforced concrete elements for strength, cracking and deformation, protection of structures from adverse influences

Introduction

1 area of use

3 Terms and definitions

4 General requirements for concrete and reinforced concrete structures

5 Requirements for concrete and reinforcement

5.1 Requirements for concrete

5.2 Standard and design values of strength and deformation characteristics of concrete

5.3 Requirements for fittings

5.4 Standard and design values of strength and deformation characteristics of reinforcement

6 Requirements for the calculation of concrete and reinforced concrete structures

6.1 General provisions

6.2 Strength calculation of concrete and reinforced concrete elements

6.3 Calculation of reinforced concrete elements for the formation of cracks

6.4 Calculation of reinforced concrete elements based on crack opening

6.5 Calculation of reinforced concrete elements based on deformations

7 Design requirements

7.1 General provisions

7.2 Requirements for geometric dimensions

7.3 Reinforcement requirements

7.4 Protection of structures from the adverse effects of environmental influences

8 Requirements for the manufacture, construction and operation of concrete and reinforced concrete structures

8.2 Fittings

8.3 Formwork

8.4 Concrete and reinforced concrete structures

8.5 Quality control

9 Requirements for restoration and strengthening of reinforced concrete structures

9.1 General provisions

9.2 Field surveys of structures

9.3 Verified structural calculations

9.4 Strengthening reinforced concrete structures

Appendix B Reference. Terms and Definitions

CONCRETE AND REINFORCED CONCRETE
CONSTRUCTIONS.
BASIC POINTS

Updated edition

SNiP 52-01-2003

With change No. 1, No. 2, No. 3

Moscow 2015

Preface

Rulebook Details

1 CONTRACTOR - NIIZHB im. A.A. Gvozdev - Institute of OJSC "National Research Center "Construction".

Amendment No. 1 to SP 63.13330.2012 - NIIZHB im. A.A. Gvozdeva - Institute of JSC "Research Center "Construction"

2 INTRODUCED by the Technical Committee for Standardization TC 465 “Construction”

4 APPROVED by order of the Ministry of Regional Development of the Russian Federation (Ministry of Regional Development of Russia) dated December 29, 2011 No. 635/8 and put into effect on January 1, 2013. In SP 63.13330.2012 “SNiP 52-01-2003 Concrete and reinforced concrete structures. Basic provisions" amendment No. 1 was introduced and approved by order of the Ministry of Construction and Housing and Communal Services of the Russian Federation dated July 8, 2015 No. 493/pr, order dated November 5, 2015 No. 786/pr "On amendments to the order of the Ministry of Construction of Russia dated July 8, 2015 No. 493/pr", and came into force on July 13, 2015.

5 REGISTERED by the Federal Agency for Technical Regulation and Metrology (Rosstandart).

Items, tables, and appendices to which changes have been made are marked in this set of rules with an asterisk.

Introduction

This set of rules has been developed taking into account the mandatory requirements established in the Federal Laws of December 27, 2002 No. 184-FZ “On Technical Regulation”, dated December 30, 2009 No. 384-FZ “Technical Regulations on the Safety of Buildings and Structures” and contains requirements for the calculation and design of concrete and reinforced concrete structures of industrial and civil buildings and structures.

The set of rules was developed by the team of authors of the NIIZHB named after. A.A. Gvozdev - Institute of OJSC "National Research Center "Construction" (work supervisor - Doctor of Technical Sciences T.A. Mukhamediev; Doctor of Engineering sciences A.S. Zalesov, A.I. Zvezdov, E.A. Chistyakov, Ph.D. tech. sciences S.A. Zenin), with the participation of RAASN (Doctor of Technical Sciences V.M. Bondarenko, N.I. Karpenko, IN AND. Travush) and OJSC "TsNIIpromzdaniy" (Doctor of Technical Sciences E.N. Kodysh, N.N. Trekin, Eng. I.K. Nikitin).

Amendment No. 3 to the set of rules was developed by the team of authors of JSC “Scientific Research Center “Construction” - NIIZhB im. A.A. Gvozdeva (head of the development organization - Doctor of Technical Sciences A.N. Davidyuk, topic leader - Candidate of Technical Sciences V.V. Dyachkov, D.E. Klimov, S.O. Slyshenkov).

(Changed edition. Amendment No. 3)

SET OF RULES

CONCRETE AND REINFORCED CONCRETE STRUCTURES.
BASIC POINTS

Concrete and won concrete construction
Design requirements

Date of introduction 2013-01-01

1 area of use

The requirements of this set of rules do not apply to the design of steel-reinforced concrete structures, fiber-reinforced concrete structures, concrete and reinforced concrete structures of hydraulic structures, bridges, pavements of highways and airfields and other special structures, as well as to structures made from concrete with an average density of less than 500 and over 2500 kg/ m 3, concrete polymers and polymer concretes, concretes with lime, slag and mixed binders (except for their use in cellular concrete), gypsum and special binders, concretes with special and organic fillers, concrete with a large-porous structure.

2* Normative references

This set of rules uses regulatory references to the following documents:

In other reinforced concrete structures, the formation of cracks is allowed, and they are subject to requirements to limit the width of the opening of cracks.

4.5 Safety, serviceability, durability of concrete and reinforced concrete structures and other requirements established by the design task must be ensured by fulfilling:

requirements for concrete and its components;

requirements for fittings;

requirements for structural calculations;

design requirements;

technological requirements;

operating requirements.

Design values of loads and impacts are taken depending on the type of design limit state and design situation.

(Changed edition.Change No. 2).

5 Requirements for the calculation of concrete and reinforced concrete structures

5.1 General provisions

5.1.1 Calculations of concrete and reinforced concrete structures should be made in accordance with the requirements of GOST 27751 for limit states, including:

limit states of the first group, leading to complete unsuitability for operation of structures;

limit states of the second group, which impede the normal operation of structures or reduce the durability of buildings and structures compared to the intended service life.

Calculations must ensure the reliability of buildings or structures throughout their entire service life, as well as during the performance of work in accordance with the requirements for them.

Calculations for limit states of the first group include:

strength calculation;

calculation of shape stability (for thin-walled structures);

calculation of position stability (tipping over, sliding, floating).

Calculations for limit states of the second group include:

calculation for crack formation;

calculation of crack opening;

calculation based on deformations.

For structures in which the formation of cracks is not allowed, requirements for the absence of cracks must be ensured. In this case, crack opening calculations are not performed.

5.1.2 Calculation of concrete and reinforced concrete structures (linear, planar, spatial, massive) for the limit states of the first and second groups is carried out according to stresses, forces, deformations and displacements calculated from external influences in the structures and systems of buildings and structures formed by them, taking into account the physical nonlinearity (inelastic deformations of concrete and reinforcement), possible formation of cracks and, in necessary cases, anisotropy, accumulation of damage and geometric nonlinearity (the effect of deformations on changes in forces in structures).

In statically indeterminate structures, it is necessary to take into account the redistribution of forces in the elements of the system due to the formation of cracks and the development of inelastic deformations in concrete and reinforcement up to the occurrence of a limit state in the element. In the absence of calculation methods that take into account the inelastic properties of reinforced concrete, as well as for preliminary calculations taking into account the inelastic properties of reinforced concrete, forces and stresses in statically indeterminate structures and systems can be determined under the assumption of elastic operation of reinforced concrete elements. In this case, it is recommended to take into account the influence of physical nonlinearity by adjusting the results of linear calculations based on data from experimental studies, nonlinear modeling, calculation results of similar objects and expert assessments.

When calculating structures for strength, deformation, formation and opening of cracks based on the finite element method, the conditions of strength and crack resistance for all finite elements making up the structure, as well as the conditions for the occurrence of excessive movements of the structure, must be checked. When assessing the limit state for strength, it is allowed to assume that individual finite elements are destroyed if this does not entail progressive destruction of the building or structure, and after the load in question expires, the serviceability of the building or structure is maintained or can be restored.

5.1.3 When calculating concrete and reinforced concrete structures based on limit states, various design situations should be considered in accordance with GOST 27751, including the stages of manufacturing, transportation, construction, operation, emergency situations, as well as fire.

(Changed edition. Amendment No. 2).

5.1.4 Calculations of concrete and reinforced concrete structures should be made for all types of loads that meet the functional purpose of buildings and structures, taking into account the influence of the environment (climatic influences and water - for structures surrounded by water), and, if necessary, taking into account the effects of fire, technological temperature and humidity influences and the effects of aggressive chemical environments.

5.1.5 Calculations of concrete and reinforced concrete structures are carried out for the action of bending moments, longitudinal forces, transverse forces and torques, as well as for the local action of the load.

5.1.6 When calculating elements of prefabricated structures for the impact of forces arising during their lifting, transportation and installation, the load from the mass of the elements should be taken with a dynamic coefficient equal to:

1.60 - during transportation,

1.40 - during lifting and installation.

It is allowed to accept lower, justified in accordance with the established procedure, values of the dynamism coefficients, but not lower than 1.25.

5.1.7 When calculating concrete and reinforced concrete structures, one should take into account the peculiarities of the properties of various types of concrete and reinforcement, the influence on them of the nature of the load and the environment, reinforcement methods, the compatibility of the reinforcement and concrete (in the presence and absence of adhesion of the reinforcement to the concrete), the manufacturing technology of structural types of reinforced concrete elements of buildings and structures.

5.1.8 Calculation of prestressed structures should be made taking into account the initial (preliminary) stresses and deformations in the reinforcement and concrete, losses of prestress and the characteristics of the transfer of prestress to concrete.

5.1.9 In monolithic structures, the strength of the structure must be ensured, taking into account the working joints of concreting.

5.1.10 When calculating prefabricated structures, the strength of nodal and butt joints of prefabricated elements made by connecting steel embedded parts, outlets of reinforcement and embedding with concrete must be ensured.

Calculation of elements should be carried out along the most dangerous sections located at an angle relative to the direction of the forces acting on the element, based on calculation models that take into account the operation of concrete and reinforcement under volumetric stress conditions.

5.1.14 For structures of complex configuration (for example, spatial), in addition to calculation methods for assessing bearing capacity, crack resistance and deformability, test results of physical models can also be used.

5.1.15* Calculation and design of structures with composite polymer reinforcement are recommended to be carried out according to special rules, taking into account the application.

5.2 Requirements for strength calculations of concrete and reinforced concrete elements

5.2.1 Calculation of concrete and reinforced concrete elements for strength is carried out:

for normal sections (under the action of bending moments and longitudinal forces) - according to a nonlinear deformation model. For simple types of reinforced concrete structures (rectangular, T- and I-sections with reinforcement located at the upper and lower edges of the section), it is allowed to perform calculations based on ultimate forces;

along inclined sections (under the action of transverse forces), over spatial sections (under the action of torques), under the local action of a load (local compression, punching) - according to ultimate forces.

Calculation of the strength of short reinforced concrete elements (short consoles and other elements) is carried out on the basis of a frame-rod model.

5.2.2 Calculation of the strength of concrete and reinforced concrete elements based on ultimate forces is made from the condition that the force from external loads and influences F in the section under consideration should not exceed the maximum force F u lt which can be perceived by an element in this section

F ≤ F ult.

Strength calculation of concrete elements

5.2.3 Concrete elements, depending on their operating conditions and the requirements placed on them, should be calculated using normal sections according to ultimate forces without taking into account (see) or taking into account (see) the resistance of concrete in the tensile zone.

5.5 Requirements for the calculation of reinforced concrete elements based on deformations

5.5.1 Calculation of reinforced concrete elements by deformations is carried out from the condition according to which deflections or movements of structures f from the action of external load should not exceed the maximum permissible values of deflections or movements f u lt.

f ≤ f u lt.

5.5.2 Deflections or displacements of reinforced concrete structures are determined according to the general rules of structural mechanics, depending on the bending, shear and axial deformation characteristics of the reinforced concrete element in sections along its length (curvature, shear angles, etc.).

5.5.3 In cases where the deflections of reinforced concrete elements mainly depend on bending deformations, the values of the deflections are determined by the curvatures of the elements or by the rigidity characteristics.

The curvature of a reinforced concrete element is determined as the quotient of the bending moment divided by the bending stiffness of the reinforced concrete section.

5.5.4 Calculation of deformations of reinforced concrete elements should be made taking into account the duration of the loads established by the relevant regulatory documents.

When calculating deflections, the stiffness of sections of an element should be determined taking into account the presence or absence of cracks normal to the longitudinal axis of the element in the tension zone of their cross-section.

5.5.5 The values of the maximum permissible deformations are taken in accordance with the instructions. Under the action of constant and temporary long-term and short-term loads, the deflection of reinforced concrete elements in all cases should not exceed 1/150 of the span and 1/75 of the cantilever overhang.

6 Materials for concrete and reinforced concrete structures

6.1 Concrete

6.1.1 For concrete and reinforced concrete structures designed in accordance with the requirements of this set of rules, the following structural concrete should be provided:

heavy medium density from 2200 to 2500 kg/m 3 inclusive;

fine-grained with medium density from 1800 to 2200 kg/m 3 ;

cellular;

straining.

6.1.2 When designing concrete and reinforced concrete structures in accordance with the requirements for specific structures, the type of concrete and its standardized quality indicators (GOST 25192, GOST 4.212), controlled in production, must be established.

6.1.3 The main standardized and controlled indicators of concrete quality are:

compressive strength class IN;

axial tensile strength class B t;

frost resistance grade F;

waterproof grade W;

medium density brand D;

self-tension grade S p.

IN corresponds to the cubic compressive strength of concrete, MPa, with a probability of 0.95 (standard cubic strength).

B t corresponds to the value of concrete axial tensile strength, MPa, with a probability of 0.95 (standard concrete strength).

Concrete grade for frost resistance F corresponds to the minimum number of cycles of alternating freezing and thawing that the sample can withstand during standard testing.

Concrete grade for water resistance W corresponds to the maximum value of water pressure (in MPa⋅ 10 -1) withstood by the concrete sample during testing.

Concrete grade by average density D corresponds to the average value of the volumetric mass of concrete (kg/m3).

The self-stressing grade of prestressing concrete is the value of the prestress in concrete, MPa, created as a result of its expansion at a longitudinal reinforcement coefficient of μ = 0.01.

Standardized indicators of concrete quality must be ensured by appropriate design of the composition of the concrete mixture (based on the characteristics of materials for concrete and requirements for concrete), technology for preparing the concrete mixture and performing concrete work in the manufacture (construction) of concrete and reinforced concrete products and structures. Standardized indicators of concrete quality must be monitored both during the production process and directly in manufactured structures.

The necessary standardized indicators of concrete quality should be established when designing concrete and reinforced concrete structures in accordance with the calculations and conditions of manufacture and operation of structures, taking into account various environmental influences and the protective properties of concrete in relation to the accepted type of reinforcement.

Concrete class by compressive strength IN prescribed for all types of concrete and structures.

Concrete class for axial tensile strength B t are prescribed in cases where this characteristic is of primary importance in the operation of the structure and is controlled in production.

Concrete grade for frost resistance F prescribed for structures exposed to alternating freezing and thawing.

Concrete grade for water resistance W are prescribed for structures that are subject to requirements for limiting water permeability.

The self-stressing grade of concrete must be assigned for self-stressing structures when this characteristic is taken into account in the calculations and controlled in production.

6.1.4 For concrete and reinforced concrete structures, the following classes and grades of concrete should be provided, given in the tables -.

Concrete	Compressive strength classes
Heavy concrete	B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30; B35; B40; B45; B50; B55; B60; B70; B80; B90; B100
Tensile concrete	IN 20; B25; B30; B35; B40; B45; B50; B55; B60; B70
Fine-grained concrete groups:
A - natural hardening or heat treated at atmospheric pressure	B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30; B35; B40
B - autoclaved	B15; IN 20; B25; B30; B35; B40; B45; B50; B55; B60
Lightweight concrete grades of average density:
D800, D900	B2.5; B3.5; AT 5; B7.5
D1000, D1100	B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; At 12.5
D1200, D1300	B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20
D1400, D1500	B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30
D1600, D1700	B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30; B35; B40
D1800, D1900	B15; IN 20; B25; B30; B35; B40
D2000	B25; B30; B35; B40
Cellular concrete with medium density grades:	Autoclaved	Non-autoclaved
D500	B 1.5; AT 2; B2.5
D600	B 1.5; AT 2; B2.5; B3.5	B1.5; AT 2
D700	AT 2; B2.5; B3.5; AT 5	B1.5; AT 2; B2.5
D800	B2.5; B3.5; AT 5; B7.5	AT 2; B2.5; B3.5
D900	B3.5; AT 5; B7.5; AT 10	B2.5; B3.5; AT 5
D1000	B7.5; AT 10 O'CLOCK; B12.5	AT 5; B7.5
D1100	B10; B12.5; B15; B17.5	B7.5; AT 10
D1200	B12.5; B15; B17.5; IN 20	AT 10 O'CLOCK; B12.5
Porous concrete with medium density grades:
D800, D900, D1000	B2.5; B3.5; AT 5
D1100, D1200, D1300	B7.5
D1400	B3.5; AT 5; B7.5
Note - In this set of rules, the terms “lightweight concrete” and “porous concrete” are used respectively to designate lightweight concrete with a dense structure and lightweight concrete with a porous structure (with a degree of porosity over 6%).

For above-ground structures exposed to atmospheric influences of the environment at a calculated negative outside air temperature during the cold period from minus 5 ° C to minus 40 ° C, a frost resistance grade of concrete not lower than F75 is accepted. When the design temperature of the outside air is above minus 5 °C for above-ground structures, the grade of concrete for frost resistance is not standardized.

6.1.9 The grade of concrete for water resistance should be assigned depending on the requirements for structures, their operating mode and environmental conditions in accordance with SP 28.13330.

For above-ground structures exposed to atmospheric influences at a calculated negative outside air temperature above minus 40 °C, as well as for external walls of heated buildings, the grade of concrete for water resistance is not standardized.

6.1.10 The main strength characteristics of concrete are standard values:

concrete resistance to axial compression R b, n;

concrete axial tensile strength R bt,n.

Standard values of concrete resistance to axial compression (prismatic strength) and axial tension (when assigning a concrete class for compressive strength) are taken depending on the concrete class for compressive strength B according to table.

When assigning a concrete class based on axial tensile strength B t standard values of concrete axial tensile strength R bt,n are taken equal to the numerical characteristic of the concrete class for axial tension.

6.1.12 If necessary, calculated values of strength characteristics concrete is multiplied by the following operating conditions coefficients γ bi, taking into account the characteristics of concrete in a structure (nature of load, environmental conditions, etc.):

a) γ b 1 - for concrete and reinforced concrete structures, added to the calculated resistance values Rb And R b t and taking into account the influence of the duration of the static load:

γ b 1 = 1.0 for short-term (short-term) load action;

γ b 1 = 0.9 with prolonged (long-term) load action. For cellular and porous concrete γ b 1 = 0,85;

b) γ b 2 - for concrete structures, entered into the calculated resistance values Rb and taking into account the nature of destruction of such structures, γ b 2 = 0,9;

c) γ b 3 - For concrete and reinforced concrete structures concreted in a vertical position with a concreting layer height of over 1.5 m, added to the calculated value of concrete resistance Rb, γ b 3 = 0,85;

d) γ b 4 - for cellular concrete, added to the calculated value of concrete resistance Rb:

γ b 4 = 1.00 - when the moisture content of cellular concrete is 10% or less;

γ b 4 = 0.85 - when the moisture content of cellular concrete is more than 25%;

by interpolation - when the moisture content of cellular concrete is more than 10% and less than 25%.

The influence of alternating freezing and thawing, as well as negative temperatures, is taken into account by the concrete operating conditions coefficient γ b 5 ≤ 1.0. For above-ground structures exposed to atmospheric influences of the environment at a design temperature of outside air during the cold period of minus 40 ° C and above, the coefficient γ is taken b 5 = 1.0. In other cases, the coefficient values are taken depending on the purpose of the structure and environmental conditions in accordance with special instructions.

CONCRETE AND REINFORCED CONCRETE
CONSTRUCTIONS.
BASIC POINTS

Updated edition

SNiP 52-01-2003

With change No. 1, No. 2, No. 3

Moscow 2015

Preface

Rulebook Details

1 CONTRACTOR - NIIZHB im. A.A. Gvozdev - Institute of OJSC "National Research Center "Construction".

Amendment No. 1 to SP 63.13330.2012 - NIIZHB im. A.A. Gvozdeva - Institute of JSC "Research Center "Construction"

2 INTRODUCED by the Technical Committee for Standardization TC 465 “Construction”

5 REGISTERED by the Federal Agency for Technical Regulation and Metrology (Rosstandart).

Items, tables, and appendices to which changes have been made are marked in this set of rules with an asterisk.

Introduction

(Changed edition. Amendment No. 3)

SET OF RULES

CONCRETE AND REINFORCED CONCRETE STRUCTURES.
BASIC POINTS

Concrete and won concrete construction
Design requirements

Date of introduction 2013-01-01

1 area of use

The requirements of this set of rules do not apply to the design of steel-reinforced concrete structures, fiber-reinforced concrete structures, concrete and reinforced concrete structures of hydraulic structures, bridges, pavements of highways and airfields and other special structures, as well as to structures made from concrete with an average density of less than 500 and over 2500 kg/ m 3, concrete polymers and polymer concretes, concretes with lime, slag and mixed binders (except for their use in cellular concrete), gypsum and special binders, concretes with special and organic fillers, concrete with a large-porous structure.

2* Normative references

This set of rules uses regulatory references to the following documents:

GOST 4.212-80 System of product quality indicators. Construction. Concrete. Nomenclature of indicators

GOST 380-2005 Carbon steel of ordinary quality. Stamps

GOST 535-2005 Long-rolled and shaped rolled products made of carbon steel of ordinary quality. General technical conditions

GOST 1050-2013 Metal products from unalloyed structural high-quality and special steels. General technical conditions

GOST 2590-2006 Hot-rolled round steel products. Assortment

GOST 5781-82 Hot-rolled steel for reinforcement of reinforced concrete structures. Specifications

GOST 7473-2010 Concrete mixtures. Specifications

GOST 7566-94 Metal products. Reception, labeling, packaging, transportation and storage

GOST 8267-93 Crushed stone and gravel from dense rocks for construction work. Specifications

GOST 8731-74 Hot-deformed seamless steel pipes. Technical requirements

GOST 8732-78 Hot-deformed seamless steel pipes. Assortment

GOST 8736-2014 Sand for construction work. Specifications

GOST 8829-94 Prefabricated reinforced concrete and concrete building products. Load test methods. Rules for assessing strength, stiffness and crack resistance

GOST 10060-2012 Concrete. Methods for determining frost resistance

GOST 10180-2012 Concrete. Methods for determining strength using control samples

GOST 10181-2014 Concrete mixtures. Test methods

GOST 10884-94 Reinforcing steel thermomechanically strengthened for reinforced concrete structures. Specifications

GOST 10922-2012 Reinforcement and embedded products, their welded, knitted and mechanical connections for reinforced concrete structures. General technical conditions

GOST 12730.0-78 Concrete. General requirements for methods for determining density, humidity, water absorption, porosity and water resistance

GOST 12730.1-78 Concrete. Density determination method

GOST 12730.5-84 Concrete. Methods for determining water resistance

GOST 13015-2012 Concrete and reinforced concrete products for construction. General technical requirements. Rules for acceptance, labeling, transportation and storage

GOST 13087-81 Concrete. Methods for determining abrasion

GOST 14098-2014 Welded connections of reinforcement and embedded products of reinforced concrete structures. Types, design and dimensions

GOST 17624-2012 Concrete. Ultrasonic method for determining strength.

GOST 18105-2010 Concrete. Rules for monitoring and assessing strength.

GOST 22690-2015 Concrete. Determination of strength by mechanical methods of non-destructive testing

GOST 23732-2011 Water for concrete and mortars. Specifications

GOST 23858-79 Welded butt and tee connections for reinforced concrete structures. Ultrasonic quality control methods. Acceptance rules

GOST 24211-2008 Additives for concrete and mortars. General technical requirements

GOST 24705-2004 (ISO 724:1993) Basic standards

interchangeability. Metric thread. Main Dimensions

GOST 25192-2012 Concrete. Classification and general technical requirements

GOST 25781-83 Steel molds for the manufacture of reinforced concrete products. Specifications

GOST 26633-2015 Heavy and fine-grained concrete. Specifications

GOST 27005-2014 Lightweight and cellular concrete. Average Density Control Rules

GOST 27006-86 Concrete. Squad selection rules

GOST 27751-2014 Reliability of building structures and foundations. Basic provisions

GOST 28570-90 Concrete. Methods for determining strength using samples taken from structures

GOST 31108-2016 General construction cements. Specifications

GOST 31938-2012 Composite polymer reinforcement for reinforcing concrete structures. General technical conditions

GOST 33530-2015 (ISO 6789:2003) Assembly tool for standardized tightening of threaded connections. Torque keys. General technical conditions

GOST R 52085-2003 Formwork. General technical conditions

GOST R 52086-2003 Formwork. Terms and Definitions

GOST R 52544-2006 Rolled welded reinforcement bars of periodic profiles of classes A 500C and B 500C for reinforcing reinforced concrete structures. Specifications

SP 2.13130.2012 “Fire protection systems. Ensuring the fire resistance of protected objects" (with amendment No. 1)

SP 14.13330.2014 “SNiP II-7-81* Construction in seismic areas” (with amendment No. 1)

SP 16.13330.2017 “SNiP II-23-81* Steel structures”

SP 20.13330.2016 “SNiP 2.01.07-85* Loads and impacts”

SP 22.13330.2016 “SNiP 2.02.01-83* Foundations of buildings and structures”

SP 28.13330.2017 “SNiP 2.03.11-85 Protection of building structures from corrosion”

SP 48.13330.2011 “SNiP 12-01-2004 Organization of construction” (with amendment No. 1)

SP 50.13330.2012 “SNiP 23-02-2003 Thermal protection of buildings”

SP 70.13330.2012 “SNiP 3.03.01-87 Load-bearing and enclosing structures” (with amendment No. 1)

SP 122.13330.2012 “SNiP 32-04-97 Railway and road tunnels” (with amendment No. 1)

SP 130.13330.2011 “SNiP 3.09.01-85 Production of prefabricated reinforced concrete structures and products”

SP 131.13330.2012 “SNiP 23-01-99* Construction climatology” (with amendment No. 2)

Note - When using this set of rules, it is advisable to check the validity of the reference documents in the public information system - on the official website of the federal executive body in the field of standardization on the Internet or according to the annual information index “National Standards”, which was published as of January 1 of the current year, and on issues of the monthly information index “National Standards” for the current year. If a referenced document to which an undated reference is given is replaced, it is recommended that the current version of that document be used, taking into account any changes made to that version. If a reference document to which a dated reference is given is replaced, it is recommended to use the version of this document with the year of approval (acceptance) indicated above. If, after the approval of this set of rules, a change is made to the referenced document to which a dated reference is made that affects the provision to which the reference is given, then it is recommended that this provision be applied without taking into account this change. If the reference document is canceled without replacement, then the provision in which a reference to it is given is recommended to be applied in the part that does not affect this reference. It is advisable to check information on the operation of sets of rules in the Federal Information Fund of Standards.”

(Changed edition. Amendment No. 2, No. 3).

3* Terms and definitions

In this set of rules the following terms with corresponding definitions are used:

3.1 anchoring of reinforcement: Ensuring that the reinforcement accepts the forces acting on it by inserting it to a certain length beyond the design cross-section or by installing special anchors at the ends.

3.2 structural fittings: Reinforcement installed without calculation for structural reasons.

3.3 prestressed reinforcement: Reinforcement that receives initial (preliminary) stresses during the manufacturing process of structures before the application of external loads during the operation stage.

3.4 working fittings: Fittings installed according to calculation.

3.4a bolted connection: Connecting reinforcing bars using a long coupling in which the reinforcing bars are secured using pointed bolts that cut into the body of the reinforcing bar.

3.4b deformability of mechanical connection Δ: The value of residual deformation of a mechanical connection when the stress in the connected reinforcement is equal to 0.6 σ T(0,2) .

Note - σ T(0.2) - standard value of the physical or conditional yield strength of the reinforcement being connected according to the current regulatory documents for its production.

(Introduced additionally. Amendment No. 3)

3.5 protective layer of concrete: The thickness of the concrete layer from the face of the element to the nearest surface of the reinforcing bar.

3.5a combined connection: Connection of reinforcing bars with factory-made threaded couplings pre-pressed at the ends of the reinforcing bars.

(Introduced additionally. Amendment No. 3)

3.6 concrete structures: Structures made of concrete without reinforcement or with reinforcement installed for structural reasons and not taken into account in the calculation; design forces from all impacts in concrete structures must be absorbed by concrete.

3.7 (Excluded. Amendment No. 2).

3.8 reinforced concrete structures: Structures made of concrete with working and structural reinforcement (reinforced concrete structures): design forces from all impacts in reinforced concrete structures must be absorbed by concrete and working reinforcement.

3.9 (Excluded. Amendment No. 2).

3.10 reinforced concrete reinforcement coefficient μ : The ratio of the cross-sectional area of reinforcement to the effective cross-sectional area of concrete, expressed as a percentage.

3.11 concrete grade for water resistance W : An indicator of the permeability of concrete, characterized by the maximum water pressure at which, under standard test conditions, water does not penetrate the concrete sample.

3.12 concrete grade for frost resistance F : The minimum number of freezing and thawing cycles established by standards for concrete samples tested using standard basic methods, in which their original physical and mechanical properties are maintained within standardized limits.

3.13 self-stressing concrete grade S p : The value of prestress in concrete, MPa, established by the standards, created as a result of its expansion at the coefficient of longitudinal reinforcement μ = 0,01.

3.14 medium density concrete grade D : The density value established by the standards, in kg/m 3, of concrete, which is subject to thermal insulation requirements.

3.15 massive construction: A structure for which the ratio of the surface area open to drying, m2, to its volume, m3, is equal to or less than 2.

3.15a mechanical connection of fittings: A connection consisting of a coupling and two reinforcing bars that absorb compression and tension forces.

(Introduced additionally. Amendment No. 3)

3.16 frost resistance of concrete: The ability of concrete to maintain physical and mechanical properties during repeated alternating freezing and thawing is regulated by the frost resistance grade F.

3.17 normal section: Section of an element by a plane perpendicular to its longitudinal axis.

3.18 inclined section: Section of an element by a plane inclined to its longitudinal axis and perpendicular to a vertical plane passing through the axis of the element.

3.18a pressed connection: Connecting reinforcing bars by plastic deformation without heating steel couplings using mobile equipment on a construction site or stationary in a factory environment.

(Introduced additionally. Amendment No. 3)

3.19 concrete density: The characteristics of concrete, equal to the ratio of its mass to volume, are regulated by the average density grade D.

3.20 ultimate force: The greatest force that can be absorbed by an element or its cross-section given the accepted characteristics of the materials.

3.21 permeability of concrete: The property of concrete to allow gases or liquids to pass through itself in the presence of a pressure gradient (regulated by the waterproof grade W) or ensure the diffusion permeability of substances dissolved in water in the absence of a pressure gradient (regulated by standardized values of current density and electric potential).

3.22 working section height: Distance from the compression face of the element to the center of gravity of the tension longitudinal reinforcement.

3.22a threaded connection: Connecting reinforcing bars with factory-made threaded couplings with cut internal threads corresponding to the thread profile cut on the connecting reinforcing bars.

(Introduced additionally. Amendment No. 3)

3.23 self-stressing of concrete: The compressive stress that occurs in the concrete of the structure during hardening as a result of the expansion of the cement stone under conditions of limiting this expansion is regulated by the self-stress grade S p.

3.23a coupling: A device with the necessary additional elements for mechanically connecting reinforcing bars to ensure the transfer of force from one bar to another.

(Introduced additionally. Amendment No. 3)

3.24 overlapping reinforcement joints: Connecting reinforcing bars along their length without welding by inserting the end of one reinforcing bar relative to the end of another.

3.24a collet connection: Connection of reinforcing bars made by clamping the reinforcing bars using tapered connecting plates located inside the tapered bushings.

(Introduced additionally. Amendment No. 3)

4 General requirements for concrete and reinforced concrete structures

4.1 Concrete and reinforced concrete structures of all types must meet the requirements:

on safety;

on serviceability;

in terms of durability,

as well as additional requirements specified in the design assignment.

Calculation of elements should be carried out along the most dangerous sections located at an angle relative to the direction of the forces acting on the element, based on calculation models that take into account the operation of concrete and reinforcement under volumetric stress conditions.

5.1.15* Calculation and design of structures with composite polymer reinforcement are recommended to be carried out according to special rules, taking into account the application.

5.2 Requirements for strength calculations of concrete and reinforced concrete elements

5.2.1 Calculation of concrete and reinforced concrete elements for strength is carried out:

Calculation of the strength of short reinforced concrete elements (short consoles and other elements) is carried out on the basis of a frame-rod model.

F ≤ F ult.

Strength calculation of concrete elements

Concrete	Compressive strength classes
Heavy concrete	B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30; B35; B40; B45; B50; B55; B60; B70; B80; B90; B100
Tensile concrete	IN 20; B25; B30; B35; B40; B45; B50; B55; B60; B70
Fine-grained concrete groups:
A - natural hardening or heat treated at atmospheric pressure	B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30; B35; B40
B - autoclaved	B15; IN 20; B25; B30; B35; B40; B45; B50; B55; B60
Lightweight concrete grades of average density:
D800, D900	B2.5; B3.5; AT 5; B7.5
D1000, D1100	B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; At 12.5
D1200, D1300	B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20
D1400, D1500	B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30
D1600, D1700	B7.5; AT 10 O'CLOCK; B12.5; B15; IN 20; B25; B30; B35; B40
D1800, D1900	B15; IN 20; B25; B30; B35; B40
D2000	B25; B30; B35; B40
Cellular concrete with medium density grades:	Autoclaved	Non-autoclaved
D500	B 1.5; AT 2; B2.5
D600	B 1.5; AT 2; B2.5; B3.5	B1.5; AT 2
D700	AT 2; B2.5; B3.5; AT 5	B1.5; AT 2; B2.5
D800	B2.5; B3.5; AT 5; B7.5	AT 2; B2.5; B3.5
D900	B3.5; AT 5; B7.5; AT 10	B2.5; B3.5; AT 5
D1000	B7.5; AT 10 O'CLOCK; B12.5	AT 5; B7.5
D1100	B10; B12.5; B15; B17.5	B7.5; AT 10
D1200	B12.5; B15; B17.5; IN 20	AT 10 O'CLOCK; B12.5
Porous concrete with medium density grades:
D800, D900, D1000	B2.5; B3.5; AT 5
D1100, D1200, D1300	B7.5
D1400	B3.5; AT 5; B7.5
Note - In this set of rules, the terms “lightweight concrete” and “porous concrete” are used respectively to designate lightweight concrete with a dense structure and lightweight concrete with a porous structure (with a degree of porosity over 6%).

a) γ b 1 - for concrete and reinforced concrete structures, added to the calculated resistance values Rb And R b t and taking into account the influence of the duration of the static load:

γ b 1 = 1.0 for short-term (short-term) load action;

γ b 1 = 0.9 with prolonged (long-term) load action. For cellular and porous concrete γ b 1 = 0,85;

b) γ b 2 - for concrete structures, entered into the calculated resistance values Rb and taking into account the nature of destruction of such structures, γ b 2 = 0,9;

d) γ b 4 - for cellular concrete, added to the calculated value of concrete resistance Rb:

γ b 4 = 1.00 - when the moisture content of cellular concrete is 10% or less;

γ b 4 = 0.85 - when the moisture content of cellular concrete is more than 25%;

by interpolation - when the moisture content of cellular concrete is more than 10% and less than 25%.

Snip 52 01 concrete and reinforced concrete structures. Concrete and reinforced concrete structures. Requirements for the calculation of concrete and reinforced concrete elements for strength

1 area of ​​use

2 Normative references

3 Terms and definitions

4 General requirements for concrete and reinforced concrete structures

5 Requirements for the calculation of concrete and reinforced concrete structures

5.1 General provisions

1 area of ​​use

2* Normative references

5 Requirements for the calculation of concrete and reinforced concrete structures

5.1 General provisions

5.2 Requirements for strength calculations of concrete and reinforced concrete elements

5.5 Requirements for the calculation of reinforced concrete elements based on deformations

6 Materials for concrete and reinforced concrete structures

6.1 Concrete

1 area of ​​use

2* Normative references

3* Terms and definitions

4 General requirements for concrete and reinforced concrete structures

5.2 Requirements for strength calculations of concrete and reinforced concrete elements

1 area of use

1 area of use

1 area of use