Laying brick walls during seismic events. Construction of masonry under seismic conditions, in dry, hot climates. Features of masonry during reconstruction. Brick walls

BUILDING REGULATIONS

CONSTRUCTION IN SEISMIC AREAS

SNiP II-7-81*

MINISTRY OF CONSTRUCTION OF Russia

Moscow 1995

Developed by TsNIISK im. Kucherenko NIIOSP named after. Gersevanov, NIISK, Kazakh Promstroyniproekt, TsNNIpromzdanii of the USSR State Construction Committee, TbilZNIIEP Gosgrazhdanstroy Institute of Physics of the Earth of the USSR Academy of Sciences, Institute of Structural Mechanics and Seismic Stability of the Academy of Sciences of the Georgian SSR, Institute of Mechanics and Seismic Stability of Structures of the Academy of Sciences of the Uzbek SSR, TsNNIS Ministry of Transport, VNIIG named after. Vedeneev Ministry of Energy of the USSR, Krasnoyarsk Industrial Construction Project of the Ministry of Heavy Construction of the USSR, TsNIIEPselstroy of the Ministry of Agriculture of the USSR with the participation of the Hydroproject named after. Zhuk and GruzNIIEGS Ministry of Energy of the USSR.

The new map of seismic zoning of the territory of the USSR was compiled by scientific institutions of the USSR Academy of Sciences and the academies of sciences of the Union republics (leading - the Institute of Earth Physics of the USSR Academy of Sciences) and approved by the Interdepartmental Council on Seismology and Earthquake-Resistant Construction under the Presidium of the USSR Academy of Sciences.

With the entry into force of SNiP II-7-81 from January 1, 1982, the following become invalid: chapter SNiP II-A.12-69*. "Construction in seismic areas. Design standards":

Decree of the USSR State Construction Committee dated July 3, 1976 No. 81 “On the addition of Appendix 2 of Chapter SNiP II-A.12-69”;

Decree of the USSR State Construction Committee dated August 24, 1976 No. 140 “On additions and amendments to Appendix 2 of Chapter SNiP II-A.12-69”;

Resolution of the USSR State Construction Committee dated July 28, 1980 No. 116 “On additions and amendments to Appendix 2 of Chapter SNiP II-A.12-69.”

These building codes and regulations have been amended by resolutions of the USSR State Construction Committee dated June 3, 1987 No. 106, August 16, 1989 No. 127, and the Russian Ministry of Construction dated July 26, 1995 No. 18-76.

Items, tables and appendices to which changes have been made are noted in these building codes oh and ruled with an asterisk.

Editors - Eng. F.M.Shlemin, Ph.D. tech. sciences F.V.Bobrov(Gosstroy USSR), Doctor of Engineering. sciences S.V.Polyakov, Eng. V.I. Oizerman(TsNIISK named after Kucherenko), Doctor of Physics and Mathematics. sciences V.I.Bune(IPZ AS USSR), Doctor of Engineering. sciences O.A. Savinov, Ph.D. tech. sciences N.D. Krasnikov(VNIIG), Ph.D. tech. sciences Ya.I.Natarius(Hydroproject), Ph.D. tech. sciences G.S. Shestoperov(TsNIIS) .

ATTENTION READERS!

It is necessary to take into account the approved changes in building codes and regulations and state standards published in the journal “Bulletin of Construction Equipment” and the information index “State Standards”.

1. BASIC PROVISIONS

1.1. These standards must be observed when designing buildings and structures erected in areas with seismicity of 7, 8 and 9 points.

1.2. When designing buildings and structures for construction in the specified seismic areas, the following must be done:

use materials, structures and design schemes that ensure the lowest values ​​of seismic loads;

accept, as a rule, symmetrical structural designs, uniform distribution of structural rigidities and their masses, as well as loads on the floors;

in buildings and structures made of prefabricated elements, place joints outside the zone of maximum forces, ensure solidity and homogeneity of structures using enlarged prefabricated elements;

provide conditions that facilitate the development of plastic deformations in structural elements and their connections, while ensuring the stability of the structure.

1.3. When designing buildings and structures for construction in seismic areas, the following should be taken into account:

a) intensity of seismic impact in points (seismicity);

b) repeatability of seismic impact.

Intensity and frequency should be taken from seismic zoning maps of the territory of the USSR (Appendices 1* and 2 *), adopted by the USSR Academy of Sciences, with amendments approved by the Russian Academy of Sciences.

Specified in the appendix. 1* and 2* seismicity refers to areas with soils with average seismic properties (category II according to Table 1*).

1.4. The seismicity of a construction site should be determined on the basis of seismic microzoning.

In areas for which there are no seismic microzoning maps, it is allowed to determine the seismicity of the construction site according to Table. 1*.

1.5. Construction sites with slopes steeper than 15 ° , proximity to fault planes, severe disturbance of rocks by physical and geological processes, soil subsidence, landslides, landslides, quicksand, landslides, karst, mine workings, and mudflows are unfavorable in seismic terms.

If it is necessary to construct buildings and structures on such sites, additional measures should be taken to strengthen their foundations and strengthen the structures.

1.6.* On sites where seismicity exceeds 9 points, the construction of buildings and structures is, as a rule, not allowed. If necessary, construction on such sites is permitted in agreement with the Russian Ministry of Construction.

Table 1*

Notes: 1*. Classification of a site to category I for seismic properties is allowed if the thickness of the layer corresponding to category I is more than 30 m from the black mark in the case of an embankment or the planning mark in the case of an excavation. In the case of a heterogeneous soil composition, the construction site is classified in a more unfavorable category in terms of seismic properties if, within a 10-meter layer of soil (counting from the planning mark), the layer belonging to this category has a total thickness of more than 5 m.

2. When predicting the rise of groundwater levels and watering of soils (including subsidence) during the operation of a building and structure, soil categories should be determined depending on the properties of the soil (humidity, consistency) in the soaked state.

3. When building on permafrost non-rocky soils according to principle II, if the thawing zone extends to the underlying thawed soil, the foundation soils should be considered as non-permafrost (according to their actual state after thawing).

4. For especially critical buildings and structures being built in areas with a seismicity of 6 points on construction sites with soils of category III for seismic properties, the calculated seismicity should be taken equal to 7 points.

5. When determining the seismicity of transport and transport construction sites hydraulic structures The additional requirements set out in sections 4 and 5 should be taken into account.

6. In the absence of data on consistency or moisture, clay and sandy soils with a groundwater level above 5 m are classified as category III in terms of seismic properties.

2. DESIGN LOADS

2.1. Calculation of structures and foundations of buildings and structures designed for construction in seismic areas must be carried out for basic and special combinations of loads, taking into account seismic influences.

When calculating buildings and structures (except for transport and hydraulic structures) for a special combination of loads, the values ​​of the design loads should be multiplied by the combination coefficients taken according to Table. 2.

Horizontal loads from masses on flexible suspensions, temperature climatic effects, wind loads, dynamic effects from equipment and vehicles, braking and lateral forces from the movement of cranes are not taken into account.

table 2

When determining the design vertical seismic load, the weight of the crane bridge, the weight of the trolley, and the weight of the load equal to the crane's lifting capacity should be taken into account with a factor of 0.3.

The calculated horizontal seismic load from the weight of crane bridges should be taken into account in the direction perpendicular to the axis of the crane beams. The reduction in crane loads provided for by SNiP for loads and impacts is not taken into account.

2.2. Calculations of buildings and structures for special combinations of loads taking into account seismic effects should be performed:

a) for loads determined in accordance with the instructions of clause 2.5;

b) using instrumental records of foundation accelerations during an earthquake, the most dangerous for a given building or structure, as well as synthesized accelerograms. In this case, the maximum amplitudes of foundation accelerations should be taken to be no less than 100, 200 or 400 cm/s 2 when the seismicity of construction sites is 7, 8 and 9 points, respectively.

When calculating according to point “b”, the possibility of the development of inelastic deformations of structures should be taken into account.

Growing according to item “a” should be carried out for all buildings and structures.

The calculation according to point “b” should be performed when designing especially critical structures and high (more than 16 floors) buildings.

2.3. Seismic impacts can have any direction in space.

For buildings and structures of simple geometric shape, the design seismic loads should be assumed to act horizontally in the direction of their longitudinal and transverse axes. The effect of seismic loads in the indicated directions should be taken into account separately.

When calculating structures of complex geometric shapes, the most dangerous directions of action of seismic loads for a given structure or its elements should be taken into account.

2.4. Vertical seismic load must be taken into account when calculating:

horizontal and inclined cantilever structures;

bridge spans;

frames, arches, trusses, spatial coverings of buildings and structures with a span of 24 meters or more;

structures for stability against overturning or sliding;

stone structures(according to clause 3.37).

2.5 . Design seismic load Sik in the selected direction, applied to the point k and corresponding i the th tone of natural vibrations of buildings or structures is determined by the formula

S ik = K 1 K 2 S 0ik ,(1)

Where TO 1 - coefficient taking into account permissible damage to buildings and structures, taken according to table. 3;

k 2 - coefficient taking into account design solutions of buildings and structures, taken according to table. 4 or the instructions of section. 5;

S 0ik - seismic load value for i th tone of natural vibrations of a building or structure, determined under the assumption of elastic deformation of structures according to the formula

S oik =Q k Ab iKwnik, (2)

Where Q k - k, determined taking into account the design loads on structures in accordance with clause 2.1 (Fig. 1);

A - coefficient, the values ​​of which should be taken equal to 0.1; 0.2; 0.4, respectively, for calculated seismicity 7, 8, 9 points;

b i- dynamic coefficient corresponding i-th tone of natural vibrations of buildings or structures, adopted in accordance with clause 2.6;

TOw- coefficient accepted according to the table. 6 or in accordance with the instructions of section. 5;

Pik- coefficient depending on the form of deformation of a building or structure during its own vibrations along i-th tone and from the location of the load, determined according to clause 2.7.

Note: Design seismicity of buildings and structures, as well as coefficient values K 1, accepted in agreement with the organization approving the project in accordance with table. 3 and 5.

2.6. * Dynamic coefficient b i depending on the calculated period of natural oscillations Ti buildings or structures according to i when determining seismic loads, the th tone should be taken according to formulas (3, 4, 5) or Fig. 2.

at Ti £ 0.08 s b i = 1+15 Ti

at 0.08 s<Ti £0.318c b i = 2,2 (3)

at Ti > 0.318 s b i = 0,7/Ti

For soils of categories II and III with a layer thickness equal to or less than 30 m (curve 2)

at Ti £ 0.1 s b i = 1+15 Ti

at 0.1 s<Ti £0.4c b i = 2,5 (4)

at Ti > 0.4 s b i = 1/Ti

For soils of categories II and III with a layer thickness of more than 30 m (curve 3)

at Ti £ 0.2 s b i = 1+7,5 Ti

at 0.2 s<Ti £0.76c b i = 2,5 (5)

at Ti > 0.76 s b i = 1,9/Ti

In all cases the values b i, must be taken at least 0.8.

Note*. When calculating transport and hydraulic structures, the choice of dependencies b i(T i) provided for in this paragraph should be carried out in accordance with the instructions in sections 4 and 5.

Regional dependencies are allowed b i(T i), approved by the Ministry of Construction of Russia.

2.7. For buildings and structures calculated using a cantilever scheme, the value n ik should be determined by the formula

n ik =(6)

Where Xi(Xk) And Xi(Xj) - displacement of a building or structure during natural vibrations along i-th tone at the point in question k and at all points j, where, in accordance with the calculation scheme, its weight is assumed to be concentrated;

Q j - weight of a building or structure referred to a point j, determined taking into account the design loads on the structure in accordance with clause 2.1.

2.8. For buildings up to 5 floors high inclusive with masses and floor rigidities that vary slightly in height at T 1 less than 0.4 s coefficient n k can be determined using a simplified formula

Where Xk And x j, - distances from points k And j to the top edge of the foundations.

2.9. Efforts in the structures of buildings and structures designed for construction in seismic areas, as well as in their elements, should be determined taking into account at least three modes of natural vibrations, if the periods of the first (lowest) tone of natural vibrations T 1 more than 0.4 s, and taking into account only the first form, if T 1 equal to or less than 0.4 s.

Number of modes and coefficients n ik for hydraulic structures should be taken in accordance with the instructions in Section 5.

2.10. Calculated values ​​of transverse and longitudinal forces, bending and overturning moments, normal and tangential stresses Np in structures from seismic load under the condition of its static action on the structure should be determined by the formula

Np = (8)

Where N i- values ​​of forces or stresses in the section under consideration, caused by seismic loads corresponding i th form of vibration;

P - the number of vibration modes taken into account in the calculation.

2.11. The vertical seismic load in the cases provided for in clause 2.4 (except for masonry structures) should be determined using formulas (1) and (2), while the coefficients TOw And TO 2 , are taken equal to unity.

Cantilever structures, the weight of which is insignificant compared to the weight of the building (balconies, canopies, consoles for curtain walls, etc. and their fastenings), should be calculated for a vertical seismic load with a value b n = 5.

2.12. Structures that rise above a building or structure and have insignificant cross-sections and weight in comparison with it (parapets, pediments, etc.), as well as fastenings of monuments, heavy equipment installed on the ground floor, should be calculated taking into account the horizontal seismic load calculated according to formulas (1) and (2) at b n = 5.

2.13. Walls, panels, partitions, connections between individual structures, as well as fastenings of technological equipment should be calculated for horizontal seismic load according to formulas (1) and (2) at b n corresponding to the elevation of the structure in question, but not less than 2. Friction forces are taken into account only when calculating horizontal butt joints in large-panel buildings.

2.14. When calculating structures for strength and stability, in addition to the operating conditions coefficients adopted in accordance with other SNiP Part II, an additional operating conditions coefficient should be introduced m kp, determined according to table. 7.

2.15. When calculating buildings and structures (except hydraulic structures) with a length or width of more than 30 m, in addition to the seismic load determined in accordance with clause 2.5, it is necessary to take into account the torque relative to the vertical axis of the building or structure passing through its center of rigidity. The value of the calculated eccentricity between the centers of rigidity and mass of buildings or structures at the level under consideration should be taken to be at least 0.1 V, where B is the size of the building or structure in plan in the direction perpendicular to the action of the force Sik.

2.16. When calculating retaining walls, it is necessary to take into account seismic soil pressure.

2.17. Calculation of buildings and structures taking into account seismic impact, as a rule, is carried out according to the limit states of the first group. In cases justified by technological requirements, it is allowed to carry out calculations using the second group of limit states.

Table 3

*List of structures by item. 1 is agreed with the customer.

Table 4

Notes: 1. Values K 1 should not exceed 1.5.

2. By agreement with the Ministry of Construction of Russia, the values ​​of K 2 can be clarified based on the results of experimental studies.

Table 5

* The assignment of buildings and structures to clause 2 is made by the customer.

**Buildings and structures are designed for a load corresponding to the calculated seismicity, multiplied by an additional factor of 1.5.

*** The same with a coefficient of 1.2.

Table 6

Notes: 1. For intermediate values h/b meaning TOw is accepted by interpolation.

2. When different heights floors value TOw taken according to average values h/b.

Table 7

Notes: 1. For the indicated positions. 1-4 structures of buildings and structures (except for transport and hydraulic engineering), erected in areas with frequency of 1, 2, 3, value T kr should be multiplied by 0.85; 1 or 1.5 respectively.

2. When calculating steel and reinforced concrete load-bearing structures to be used in unheated rooms or outdoors at a design temperature below minus 40 ° C, should be taken T kr = 1, in cases of checking the strength of inclined sections of columns T cr = 0.9 .

3. RESIDENTIAL, PUBLIC, INDUSTRIAL BUILDINGS AND STRUCTURES

GENERAL PROVISIONS

3.1. Buildings and structures should be separated with anti-seismic joints in cases where:

the building or structure has a complex plan shape;

adjacent sections of a building or structure have height differences of 5 m or more. In one-story buildings up to 10 m high with a calculated seismicity of 7 points, anti-seismic joints may not be installed.

3.2. Anti-seismic joints must separate buildings and structures along their entire height. It is allowed not to create a seam in the foundation, except in cases where the anti-seismic seam coincides with the sedimentary one.

3.3 . The distances between anti-seismic joints and the height of buildings should not exceed the dimensions indicated in the table. 8.

3.4*. Staircases should be closed, with window openings in the outer walls. The location and number of staircases should be determined based on the results of calculations performed in accordance with SNiP for fire safety standards for the design of buildings and structures, but at least one should be taken between anti-seismic joints in buildings with a height of more than three floors.

3.5. Anti-seismic joints should be made by constructing paired walls or frames, as well as constructing a frame and a wall.

The width of the anti-seismic joint should be determined based on the loads determined according to clause 25.

When the height of a building or structure is up to 5 m, the width of such a seam must be at least 30 mm. The width of the anti-seismic joint of a building or structure of greater height should be increased by 20 mm for every 5 m of height.

Table 8

Notes: 1. The height of the building is taken to be the difference in elevations lower level blind area or leveled surface of the ground adjacent to the building, and the top of external walls.

2. The height of hospital and school buildings with seismicity of the construction site of 8 and 9 points is limited to three above-ground floors.

3. In small settlements located in seismic areas, the construction of low-rise, mainly two-story residential buildings should be provided.

Filling anti-seismic joints should not interfere with mutual horizontal movements of compartments of a building or structure.

3.6. In cities and towns, the construction of residential buildings with walls made of mud brick, adobe and soil blocks is prohibited. In rural settlements located in areas with seismicity of 8 points, the construction of one-story buildings from these materials is allowed provided that the walls are reinforced with a wooden antiseptic frame with diagonal braces.

3.7. Rigidity of frame walls wooden houses must be provided with braces. Cobblestone and log walls should be assembled on dowels. Wooden panel houses should be designed one floor high.

3.8. When designing buildings and structures, it is necessary to provide for and check by calculation the fastening of tall and heavy equipment to the supporting structures of buildings and structures, and also take into account the seismic forces that arise in the supporting structures.

3.9. Prefabricated reinforced concrete slabs and roofs of buildings must be monolithic, rigid in the horizontal plane and connected to vertical load-bearing structures.

3.10. The rigidity of prefabricated reinforced concrete floors and coverings should be ensured by:

connecting panels (slabs) of floors and coverings and filling the joints between panels (slabs) with cement mortar;

connection devices between panels (slabs) and frame elements or walls that absorb tensile and shear forces arising in the seams.

The side edges of the panels (slabs) of floors and coverings must have a keyed or grooved surface. For connection with an anti-seismic belt or for connection with frame elements in panels (slabs), reinforcement outlets or embedded parts should be provided.

3.11*. In brick and stone buildings, the length of part of the floor panels (coverings) resting on load-bearing walls made by hand must be at least 120 mm, and on vibrating brick panels and blocks - at least 90 mm.

In one-story stone buildings with distances between walls of no more than 6 m, the installation of wooden floors (coverings) is allowed, while the floor beams should be anchored in an anti-seismic belt and a diagonal flooring should be installed along them.

3.12. Non-load-bearing elements such as partitions and frame fillings should be lightweight, usually of large-panel or frame construction and connected to walls, columns, and, if the length is more than 3 m, to floors. In buildings higher than five floors, the use of hand-made brickwork partitions is not permitted.

The strength of non-load-bearing elements and their fastenings must be confirmed in accordance with clause 2.13 by calculations for the action of design seismic loads from the plane (in all cases) and in the plane of the element (in cases where these elements work together with the load-bearing structures of the building). Partitions made of brick or stone should be reinforced over their entire length, at least every 700 mm in height, with rods with a total cross-section in the seam of at least 0.2 cm. It is allowed to make partitions suspended with limiters for moving out of the plane of the panels.

3.13. Balcony structures and their connections to floors must be designed as cantilever beams or slabs.

The extension of balconies in buildings with stone walls should not exceed 1.5 m.

3.14. The design of the foundations of buildings and structures for construction in seismic areas should be carried out in accordance with the requirements of SNiP for the design of foundations of buildings and structures.

3. I5. When building in seismic areas, a layer of grade 100 mortar with a thickness of at least 40 mm and longitudinal reinforcement with a diameter of 10 mm in the amount of three, four and six rods should be laid on top of prefabricated strip foundations with a calculated seismicity of 7, 8 and 9 points, respectively. Every 300-400 mm, the longitudinal rods must be connected by transverse rods with a diameter of 6 mm.

In the case of making basement walls from prefabricated panels structurally connected with strip foundations, laying the specified layer of mortar is not required.

3.16. In foundations and basement walls made of large blocks, masonry bonding must be ensured in each row, as well as in all corners and intersections to a depth of at least 1/3 of the height of the block; foundation blocks should be laid in a continuous strip.

To fill the joints between blocks, a solution of a grade of at least 25 should be used.

In buildings with a design seismicity of 9 points, provision should be made for laying reinforcement mesh 2 m long with longitudinal reinforcement with a total cross-sectional area of ​​at least 1 cm in horizontal joints in the corners and intersections of basement walls.

In buildings up to three floors inclusive and structures of the corresponding height with a calculated seismicity of 7 and 8 points, it is allowed to use blocks with a hollowness of up to 50% for laying basement walls.

3.17. Waterproofing layers in buildings should be made of cement mortar.

FRAME BUILDINGS

3.18. In frame buildings, the structure that absorbs horizontal seismic load can be: a frame, a frame with filling, a frame with vertical braces, diaphragms or stiffeners.

3.19. For frame buildings with a calculated seismicity of 7-8 points, the use of external stone walls and internal reinforced concrete or method frames (racks), while the requirements established for masonry buildings must be met. The height of such buildings should not exceed 7 m.

3.20. Rigid components of reinforced concrete building frames must be reinforced using welded mesh, spirals or closed clamps.

Sections of crossbars and columns adjacent to rigid frame units at a distance equal to one and a half height of their section must be reinforced with closed transverse reinforcement (clamps), installed according to calculation, but at least every 100 mm, and for frame systems with load-bearing diaphragms - at least than after 200 mm.

3.21. Diaphragms, connections and stiffeners that carry horizontal loads must be continuous along the entire height of the building and located in both directions evenly and symmetrically relative to the center of gravity of the building.

3.22. Light curtain panels should be used as enclosing wall structures of frame buildings. It is allowed to install brick or stone filling that meets the requirements of clause 3.35.

3.23. Application itself load-bearing walls made of masonry is allowed:

when the pitch of wall columns of the frame is no more than 6 m;

when the height of the walls of buildings erected on sites with seismicity 7, 8 and 9 points, respectively, is not more than 18, 16 and 9 m.

3.24. The masonry of self-supporting walls in frame buildings must be of category I or II (according to clause 3.39), have flexible connections with the frame that do not prevent horizontal displacements of the frame along the walls.

A gap of at least 20 mm must be provided between the surfaces of the walls and columns of the frame. Anti-seismic belts connected to the building frame should be installed along the entire length of the wall at the level of the covering slabs and the top of the window openings.

At the intersections of end and transverse walls with longitudinal walls, anti-seismic joints must be installed to the entire height of the walls.

3.25. Staircase and elevator shafts of frame buildings should be constructed as built-in structures with floor-to-floor sections that do not affect the rigidity of the frame, or as a rigid core that absorbs seismic loads.

For frame buildings up to 5 floors high with a calculated seismicity of 7 and 8 points, it is allowed to arrange staircases and elevator shafts within the building plan in the form of structures separated from the building frame. The construction of staircases in the form of separate structures is not permitted.

3.26. For supporting structures of tall buildings (more than 16 floors), frames with diaphragms, bracing or stiffening cores should be used.

When choosing structural schemes, preference should be given to schemes in which plastic zones appear primarily in horizontal frame elements (crossbars, lintels, strapping beams, etc.).

3.27. When designing high ranks, in addition to bending and shear deformations in the frame struts, it is necessary to take into account axial deformations, as well as the compliance of the foundations, and carry out calculations for stability against overturning.

3.28. On sites composed of category III soils (according to Table 1*), the construction of high knowledge, as well as buildings indicated in pos. 4 tables 4. not allowed.

3.29. The foundations of tall buildings on non-rocky soils should, as a rule, be made of piles or in the form of a continuous foundation slab.

LARGE PANEL BUILDINGS

3.30 . Large-panel buildings should be designed with longitudinal and transverse walls, combined with each other and with floors and coverings into a single spatial system that can withstand seismic loads.

When designing large-panel buildings it is necessary:

Wall and ceiling panels should, as a rule, be room sized;

provide for the connection of wall and ceiling panels by welding reinforcement outlets, anchor rods and embedded parts and embedding vertical wells and joint areas along horizontal seams fine-grained concrete with reduced shrinkage;

when supporting the floors on the external walls of the building and on the walls at expansion joints, provide welded joints releases of reinforcement from floor panels with vertical reinforcement of wall panels.

3.31. Reinforcement of wall panels should be done in the form of spatial frames or welded reinforcing mesh. In the case of using three-layer external wall panels, the thickness of the internal load-bearing concrete layer should be at least 100 mm.

3.32. The constructive solution of horizontal butt joints must ensure the perception of the calculated values ​​of forces in the seams. The required cross-section of metal connections in the seams between the panels is determined by calculation, but it should not be less than 1 cm 2 per 1 m of seam length, and for buildings with a height of 5 floors or less, with a site seismicity of 7 and 8 points, not less than 0.5 cm 2 per 1 m seam length. It is allowed to place no more than 65% of the vertical design reinforcement at the intersections of the walls.

3.33. Walls along the entire length and width of the building should, as a rule, be continuous.

3.34. Loggias should, as a rule, be built-in, with a length equal to the distance between adjacent walls. Where loggias are located in the plane of external walls, reinforced concrete frames should be installed.

The installation of bay windows is not permitted.

BUILDINGS WITH LOAD-LOADING WALLS MADE OF BRICK OR MASONRY

3.35. Load-bearing brick and stone walls should be constructed, as a rule, from brick or stone panels or blocks manufactured in factories using vibration, or from brick or stone masonry using mortars with special additives that increase the adhesion of the mortar to the brick or stone.

With a calculated seismicity of 7 points, it is allowed to construct load-bearing walls of masonry buildings using mortars with plasticizers without the use of special additives that increase the adhesion strength of the mortar to brick or stone.

3.36. Carrying out brick and stone masonry manually at sub-zero temperatures for load-bearing and self-supporting walls (including those reinforced with reinforcement or reinforced concrete inclusions) with a calculated seismicity of 9 points or more is prohibited.

If the calculated seismicity is 8 points or less, winter masonry may be done manually with the obligatory inclusion of additives in the solution that ensure hardening of the solution at subzero temperatures.

3.37. Calculations of stone structures must be made for the simultaneous action of horizontally and vertically directed seismic forces.

The value of the vertical seismic load with a calculated seismicity of 7-8 points should be taken equal to 15%, and with a seismicity of 9 points - 30% of the corresponding vertical static load.

The direction of action of the vertical seismic load (up or down) should be taken as more unfavorable for the stress state of the element in question.

3.38. For laying load-bearing and self-supporting walls or filling the frame, the following products and materials should be used:

a) solid or hollow brick of grade no lower than 75 with holes up to 14 mm in size; with a calculated seismicity of 7 points, the use of ceramic stones of a grade not lower than 75 is allowed;

b) concrete stones, solid and hollow blocks (including those made of lightweight concrete with a density of at least 1200 kg/m3) grade 50 and higher;

a) stones or blocks made of shell rocks, limestones of grade no less than 35 or tuffs (except felsic) grade 50 and higher.

Piece masonry of walls should be carried out using mixed cement mortars of a grade not lower than 25 in summer conditions and not lower than 50 in winter conditions. For laying blocks and panels, a solution of a grade of at least 50 should be used.

3.39. Masonry is divided into categories depending on its resistance to seismic influences.

Category of brick or stone masonry made from materials provided for in clause 3.38. is determined by the temporary resistance to axial tension along untied seams (normal adhesion), the value of which should be within the limits:

Less than 120 kPa (1.2 kgf/cm2), but not less than 60 kPa (0.6 kgf/cm2). In this case, the height of the building should be no more than three floors, the width of the walls should be at least 0.9 m, the width of the openings is no more than 2 m, and the distance between the axes of the walls is no more than 12 m.

The masonry project must include special measures for the care of hardening masonry, taking into account the climatic characteristics of the construction area. These measures should ensure that the required strength indicators of the masonry are obtained.

3.40. Design resistance values ​​for masonry R R, R Wed, R ch for untied seams should be taken according to SNiP for the design of stone and reinforced masonry structures, and for untied seams - determined according to formulas (9) - (11) depending on the value obtained as a result of tests carried out in the construction area:

R R = 0,45 (9)

R Wed = 0,7 (10)

R hl = 0.8 (11)

Values R R, R Wed and R hl should not exceed the corresponding values ​​when destroying brick or stone masonry.

3.41. The height of the floor of buildings with load-bearing walls made of brick or stone masonry, not reinforced with reinforcement or reinforced concrete inclusions, should not exceed 5, 4 and 3.5 m with a calculated seismicity of 7, 8 and 9 points, respectively.

When strengthening the masonry with reinforcement or reinforced concrete inclusions, the floor height can be taken equal to 6, 5 and 4.5 m, respectively.

In this case, the ratio of the floor height to the wall thickness should be no more than 12.

3.42. In buildings with load-bearing walls, in addition to external longitudinal walls, as a rule, there must be at least one internal longitudinal wall. The distances between the axes of transverse walls or frames replacing them must be checked by calculation and be no more than those given in Table 9.

FEATURES OF CONSTRUCTION OF STONE STRUCTURES IN EARTHQUICK AREAS

Buildings and structures erected in seismically hazardous (earthquake-prone) areas must be able to withstand seismic impacts without loss of performance, i.e., be seismic resistant. Seismic resistance of buildings and structures is ensured by the use of design solutions, structures and materials corresponding to the seismicity (intensity of seismic impact in points) of the construction site, as well as strict compliance with the rules and requirements for the construction of structures and work in seismic areas.

Constructive anti-seismic measures include: the use of earthquake-resistant structural systems; division of buildings and structures in plan into parts using anti-seismic joints; limiting the height of buildings; regulation of the conditions and scope of use of materials by their types; use of anti-seismic belts in structural schemes; reinforcement of elements of stone structures and a number of other measures provided for by design and construction standards.

These activities are specified by calculations and reflected in projects. For example, in buildings with walls made of brick or masonry at the level of floors and coverings, it is necessary to install anti-seismic belts along all longitudinal and transverse walls, made of monolithic reinforced concrete, or prefabricated with monolithic joints and continuous reinforcement. In this case, the chords of the upper floor must be connected to the masonry by vertical outlets of reinforcement. Constructive solutions of the belts and their reinforcement are indicated in the projects.

At wall junctions, reinforcing mesh 1.5 m long is placed in the masonry with a cross-section of longitudinal reinforcement in the mesh of at least 1 cm2. The grids are laid every 700 mm along the height of the masonry with seismicity - 7...8 points and after 500 mm - with 9 points. The masonry of self-supporting walls is fastened to the frame structures with flexible connections that do not prevent horizontal displacements of the frame.

Gaps of at least 20 mm are provided between the walls and columns of the frame. Along the entire length of the walls at the level of the top of the window openings, at the level of the covering, anti-seismic belts are installed, connected to the frame. The support of floor panels on masonry walls must be at least 120 mm in length, and on vibrating brick panels and blocks - at least 90 mm. Beams, purlins and floor slabs, wooden floor beams are anchored in anti-seismic belts (specific solutions are given in the projects). Ordinary lintels are not used in earthquake-prone areas. Reinforced concrete lintels are installed, as a rule, across the entire width of the walls and are embedded in the masonry to a depth of at least 350 mm; with an opening width of 1.5 m, lintels are allowed to be embedded at a depth of 250 mm.

Seismic resistance of stone buildings is also ensured by many other design techniques, for example, fastening flights of stairs and landings with floors, installing reinforced concrete frames in window and door openings of staircases, etc. All design decisions on anti-seismic measures should be strictly followed during the construction of buildings.

When using materials, the standards also provide for a number of measures. For example, in seismic areas in cities and towns, the construction of residential buildings with walls made of mud (unfired) brick, adobe and soil blocks is prohibited. In rural villages, construction from these materials is allowed only in areas with seismicity up to 8 points, and only one-story buildings, provided that the wooden walls are reinforced with an antiseptic frame with diagonal braces. For laying walls or filling the frame in seismic zones, it is allowed to use solid or hollow bricks (with holes up to 15 mm in size) of grade no lower than 75; concrete stones, solid and hollow blocks of lightweight concrete of grade no lower than 50; stones or blocks from shell rocks and limestones of a grade of at least 35 and from tuffs (except for felsite) of a grade of at least 50.

Walls are laid using mixed cement mortars of grade no lower than 25 in summer conditions and no lower than 50 in winter, with special additives that increase the adhesion of the mortar to brick or stone. With a calculated seismicity of 7 points, it is allowed to use ceramic stones of a grade of at least 75, as well as the construction of masonry building walls using mortars with plasticizers without the use of special additives that increase the adhesion strength of the mortar to brick or stone.

The most important requirement for masonry in seismic areas is the strength of adhesion to the mortar. According to their resistance to seismic influences, which is determined by the temporary resistance to axial tension along untied seams (the force of separation of a brick laid on mortar from the masonry), masonry used in seismic zones is divided into two categories.

Masonry of the first category, in which the value of normal adhesion between the stone (brick) and the mortar must be at least 180 kPa (1.8 kg/cm2). Masonry of the second category must have an adhesive strength of at least 120 kPa (1.2 kg/cm2). Masonry with an adhesion strength of mortar to brick (stone) of less than 120 kPa in earthquake-prone areas is not allowed. In some cases, with a seismicity of 7 points, when special measures are used in the project, it may be allowed (by decision of the design organization) to reduce the adhesion strength in the masonry to 60 kPa (0.6 kg/cm2).

When erecting stone structures in seismic areas, it is necessary to strictly comply with the special requirements for the work to ensure the seismic resistance of the masonry:

masonry is carried out over the entire thickness of the structure in each row; masonry is performed using single-row (chain) dressing; all masonry joints (horizontal, vertical, transverse and longitudinal) are filled completely with mortar with trimming of the mortar on the outer sides of the masonry; temporary breaks in the masonry being erected should be terminated only with an inclined groove and located outside the areas of structural reinforcement of the walls;

Before laying, the surfaces of bricks (stones, blocks) must be cleaned of dust and dirt: for laying with conventional mortars in areas with a hot climate - with a stream of water, for laying with polymer-cement mortars - with brushes or compressed air. It is necessary to strictly control the adhesion strength of the mortar to the brick (stone). In 7-day-old masonry, the adhesion value should be approximately 50% of the strength of 28-day-old masonry of the corresponding class. If the strength is lower, it is necessary to stop the work until the issue is resolved by the design organization. Before masonry work begins, the construction laboratory determines the optimal relationship between pre-wetting the local stone wall material and the water content of the mortar mixture. Solutions are used with high water-holding capacity (water separation no more than 2%). The use of cement mortars without plasticizers is not allowed. When laying in the locations of anti-seismic joints dividing the building, it is necessary to ensure that they are not filled with mortar or debris. It is prohibited to reduce their width against the design one. It is necessary to strictly carry out the measures provided for by the project for the maintenance of hardening masonry (moisturizing and preventing rapid drying, etc.). It is necessary to take into account the peculiarities of the climate and ensure that the required strength of the masonry is obtained, including when constructing structures at subzero outside temperatures with the use of antifreeze additives.

Carrying out brick and stone masonry at sub-zero temperatures with a calculated seismicity of 9 points or more is prohibited.

when the pitch of wall columns of the frame is no more than 6 m;

when the height of the walls of buildings erected on sites with seismicity 7, 8 and 9 points, respectively, is not more than 18, 16 and 9 m.

3.24. The masonry of self-supporting walls in frame buildings must be of category I or II (according to clause 3.39), have flexible connections with the frame that do not prevent horizontal displacements of the frame along the walls.

A gap of at least 20 mm must be provided between the surfaces of the walls and columns of the frame. Anti-seismic belts connected to the building frame should be installed along the entire length of the wall at the level of the covering slabs and the top of the window openings.

At the intersections of end and transverse walls with longitudinal walls, anti-seismic joints must be installed to the entire height of the walls.

3.25. Staircase and elevator shafts of frame buildings should be constructed as built-in structures with floor-to-floor sections that do not affect the rigidity of the frame, or as a rigid core that absorbs seismic loads.

For frame buildings up to 5 floors high with a calculated seismicity of 7 and 8 points, it is allowed to arrange staircases and elevator shafts within the building plan in the form of structures separated from the building frame. The construction of staircases in the form of separate structures is not permitted.

3.26. For supporting structures of tall buildings (more than 16 floors), frames with diaphragms, bracing or stiffening cores should be used.

When choosing structural schemes, preference should be given to schemes in which zones of plasticity arise primarily in the horizontal elements of the frame (crossbars, lintels, strapping beams, etc.).

3.27. When designing high ranks, in addition to bending and shear deformations in the frame struts, it is necessary to take into account axial deformations, as well as the compliance of the foundations, and carry out calculations for stability against overturning.

3.28. On sites composed of category III soils (according to Table 1*), the construction of high knowledge, as well as buildings indicated in pos. 4 tables 4. not allowed.

3.29. The foundations of tall buildings on non-rocky soils should, as a rule, be made of piles or in the form of a continuous foundation slab.

LARGE PANEL BUILDINGS

3.30. Large-panel buildings should be designed with longitudinal and transverse walls, combined with each other and with floors and coverings into a single spatial system that can withstand seismic loads.

When designing large-panel buildings it is necessary:

Wall and ceiling panels should, as a rule, be room sized;

provide for the connection of wall and ceiling panels by welding reinforcement outlets, anchor rods and embedded parts and embedding vertical wells and joint areas along horizontal seams with fine-grained concrete with reduced shrinkage;

when supporting the floors on the external walls of the building and on the walls at expansion joints, provide welded connections between the reinforcement outlets from the floor panels and the vertical reinforcement of the wall panels.

3.31. Reinforcement of wall panels should be done in the form of spatial frames or welded reinforcing mesh. In the case of using three-layer external wall panels, the thickness of the internal load-bearing concrete layer should be at least 100 mm.

3.32. The constructive solution of horizontal butt joints must ensure the perception of the calculated values ​​of forces in the seams. The required cross-section of metal connections in the seams between the panels is determined by calculation, but it should not be less than 1 cm2 per 1 m of seam length, and for buildings with a height of 5 floors or less, with a site seismicity of 7 and 8 points, not less than 0.5 cm2 per 1 m of length seam It is allowed to place no more than 65% of the vertical design reinforcement at the intersections of the walls.

3.33. Walls along the entire length and width of the building should, as a rule, be continuous.

3.34. Loggias should, as a rule, be built-in, with a length equal to the distance between adjacent walls. Where loggias are located in the plane of external walls, reinforced concrete frames should be installed.

The installation of bay windows is not permitted.

BUILDINGS WITH LOAD-LOADING WALLS MADE OF BRICK OR MASONRY

3.35. Load-bearing brick and stone walls should be constructed, as a rule, from brick or stone panels or blocks manufactured in factories using vibration, or from brick or stone masonry using mortars with special additives that increase the adhesion of the mortar to the brick or stone.

With a calculated seismicity of 7 points, it is allowed to construct load-bearing walls of masonry buildings using mortars with plasticizers without the use of special additives that increase the adhesion strength of the mortar to brick or stone.

3.36. Carrying out brick and stone masonry manually at sub-zero temperatures for load-bearing and self-supporting walls (including those reinforced with reinforcement or reinforced concrete inclusions) with a calculated seismicity of 9 points or more is prohibited.

If the calculated seismicity is 8 points or less, winter masonry may be done manually with the obligatory inclusion of additives in the solution that ensure hardening of the solution at subzero temperatures.

3.37. Calculations of stone structures must be made for the simultaneous action of horizontally and vertically directed seismic forces.

The value of the vertical seismic load with a calculated seismicity of 7-8 points should be taken equal to 15%, and with a seismicity of 9 points - 30% of the corresponding vertical static load.

The direction of action of the vertical seismic load (up or down) should be taken as more unfavorable for the stress state of the element in question.

3.38. For laying load-bearing and self-supporting walls or filling the frame, the following products and materials should be used:

a) solid or hollow brick of grade no lower than 75 with holes up to 14 mm in size; with a calculated seismicity of 7 points, the use of ceramic stones of a grade not lower than 75 is allowed;

b) concrete stones, solid and hollow blocks (including those made of lightweight concrete with a density of at least 1200 kg/m3) grade 50 and higher;

a) stones or blocks made of shell rocks, limestones of grade no less than 35 or tuffs (except felsic) grade 50 and higher.

Piece masonry of walls should be carried out using mixed cement mortars of a grade not lower than 25 in summer conditions and not lower than 50 in winter conditions. For laying blocks and panels, a solution of a grade of at least 50 should be used.

3.39. Masonry is divided into categories depending on its resistance to seismic influences.

Category of brick or stone masonry made from materials provided for in clause 3.38. is determined by the temporary resistance to axial tension along untied seams (normal adhesion), the value of which should be within the limits:

To increase normal adhesion https://pandia.ru/text/78/304/images/image016_13.gif" width="16" height="21 src="> must be specified in the project..gif" width="18" height="23"> equal to or exceeding 120 kPa (1.2 kgf/cm2), the use of brick or stone masonry is not allowed.

Note..gif" width="17 height=22" height="22"> obtained as a result of tests carried out in the construction area:

R p = 0.45 (9)

R Wed = 0,7 (10)

R hl = 0.8 (11)

Values R R, R Wed and R hl should not exceed the corresponding values ​​when destroying brick or stone masonry.

3.41. The height of the floor of buildings with load-bearing walls made of brick or stone masonry, not reinforced with reinforcement or reinforced concrete inclusions, should not exceed 5, 4 and 3.5 m with a calculated seismicity of 7, 8 and 9 points, respectively.

When strengthening the masonry with reinforcement or reinforced concrete inclusions, the floor height can be taken equal to 6, 5 and 4.5 m, respectively.

In this case, the ratio of the floor height to the wall thickness should be no more than 12.

3.42. In buildings with load-bearing walls, in addition to external longitudinal walls, as a rule, there must be at least one internal longitudinal wall. The distances between the axes of transverse walls or frames replacing them must be checked by calculation and be no more than those given in Table 9.

Table 9

Note: It is allowed to increase the distances between walls made of complex structures by 30% compared to those indicated in Table 9.

3.43. The dimensions of the wall elements of stone buildings should be determined by calculation. They must meet the requirements given in table. 10.

3.44. At the level of floors and coverings, anti-seismic belts should be installed along all longitudinal and transverse walls, made of monolithic reinforced concrete or prefabricated with monolithic joints and continuous reinforcement. Anti-seismic belts of the upper floor must be connected to the masonry by vertical outlets of reinforcement.

In buildings with monolithic reinforced concrete floors embedded along the contours of the walls, anti-seismic belts at the level of these floors may not be installed.

3.45. The antiseismic belt (with a supporting section of the floor) should, as a rule, be installed across the entire width of the wall; in external walls with a thickness of 500 mm or more, the width of the belt can be 100-150 mm less. The height of the belt should be at least 150 mm, grade of concrete 1 - not lower than 150.

Anti-seismic belts must have longitudinal reinforcement 4 d l0 with a calculated seismicity of 7-8 points and not less than 4 d 12 - at 9 points.

3.46. At the junctions of the walls, reinforcing mesh with a cross-section of longitudinal reinforcement with a total area of ​​at least 1 cm2, a length of 1.5 m must be placed in the masonry every 700 mm in height with a calculated seismicity of 7-8 points and after 500 mm - with 9 points.

Sections of walls and pillars above the attic floor, having a height of more than 400 mm, must be reinforced or reinforced with monolithic reinforced concrete inclusions anchored in an anti-seismic belt.

Brick pillars are allowed only with a calculated seismicity of 7 points. In this case, the grade of mortar should be no lower than 50, and the height of the pillars should not be more than 4 m. The pillars should be connected in two directions by beams anchored into the walls.

3.47. The seismic resistance of the stone walls of a building should be increased by using reinforcement meshes, creating an integrated structure, prestressing the masonry, or other experimentally proven methods.

Vertical reinforced concrete elements (cores) must be connected to anti-seismic belts.

Reinforced concrete inclusions in the masonry of complex structures should be made open on at least one side.

Table 10

When designing complex structures as frame systems, anti-seismic belts and their interfaces with the racks must be calculated and designed as frame elements, taking into account the filling work. In this case, the grooves provided for concreting the racks must be open on at least two sides. If complex structures are made with reinforced concrete inclusions at the ends of the walls, the longitudinal reinforcement must be securely connected with clamps laid in the horizontal joints of the masonry. Concrete inclusions must be no lower than grade 150, rolling must be carried out with a solution of grade no lower than 50, and the amount of longitudinal reinforcement should not exceed 0.8% of the cross-sectional area of ​​the concrete walls.

Note: The load-bearing capacity of reinforced concrete inclusions located at the ends of the piers, taken into account when calculating seismic effects, should not be taken into account when calculating sections for the main combination of loads.

3.48. In buildings with load-bearing walls, the first floors used for shops and other premises that require large free space should be made of reinforced concrete structures.

3.49. Lintels should, as a rule, be installed over the entire thickness of the wall and embedded in the masonry to a depth of at least 350 mm. With an opening width of up to 1.5 m, sealing of lintels is allowed at 250 mm.

3.50. Beams for staircase landings should be embedded in the masonry to a depth of at least 250 mm and anchored.

It is necessary to provide for the fastening of steps, stringers, prefabricated flights, and the connection of landings with floors. The construction of cantilever steps embedded in masonry is not allowed. Door and window openings in the chamber walls of staircases with a calculated seismicity of 8-9 points should, as a rule, have a reinforced concrete frame.

3.51. In buildings with a height of three or more floors with load-bearing walls made of brick or masonry with a calculated seismicity of 9 points, exits from stairwells should be arranged on both sides of the building.

REINFORCED CONCRETE STRUCTURES

3.52. When calculating the strength of normal sections of bent and eccentrically compressed elements, the limiting characteristic of the compressed zone of concrete should be taken according to SNiP for the design of concrete and reinforced concrete structures with a coefficient of 0.85.

3.53. In eccentrically compressed elements, as well as in the compressed zone of bending elements with a calculated seismicity of 8 and 9 points, clamps should be installed according to calculations at distances: at R ac 400 MPa (4000 kgf/cm2) - no more than 400 mm and with knitted frames - no more than 12 d, and with welded frames - no more than 15 d at R ac ³ 450 MPa (4500 kgf/cm2) - no more than 300 mm and with knitted frames - no more than 10 d, and with welded frames - no more than 12 d, Where d- the smallest diameter of compressed longitudinal rods. In this case, the transverse reinforcement must ensure fastening of the compressed rods from bending in any direction.

The distances between clamps of eccentrically compressed elements in places where working reinforcement is overlapped without welding should be taken no more than 8 d.

If the total saturation of an eccentrically compressed element with longitudinal reinforcement exceeds 3%, the clamps should be installed at a distance of no more than 8 d and no more than 250mm.

3.54. In columns of frame frames of multi-storey buildings with a design seismicity of 8 and 9 points, the spacing of clamps (except for the requirements set out in clause 3.53) should not exceed 1/2 h, and for frames with load-bearing diaphragms - no more h, Where h- the smallest side size of columns of rectangular or I-section. The diameter of the clamps in this case should be at least 8 mm.

3.55. In knitted frames, the ends of the clamps must be bent around the longitudinal reinforcement rod and inserted into the concrete core by at least 6 d clamp.

3.56. Elements of prefabricated columns of multi-story frame buildings should, if possible, be enlarged into several floors. The joints of precast columns must be located in an area with lower bending moments. Overlapping longitudinal reinforcement of columns without welding is not allowed.

3.57. In prestressed structures subject to design for a special combination of loads taking into account seismic effects, the forces determined from the strength conditions of the sections must exceed the forces absorbed by the section during the formation of cracks by at least 25% .

3.58. In prestressed structures, it is not allowed to use reinforcement for which the relative elongation after rupture is below 2%.

3.59. In buildings and structures with a calculated seismicity of 9 points without special anchors, it is not allowed to use reinforcing ropes and periodic profile rod reinforcement with a diameter of more than 28 mm.

3.60. In prestressed structures with reinforcement tensioned on concrete, the prestressed reinforcement should be placed in closed channels, which are subsequently sealed with concrete or mortar.

4. TRANSPORT FACILITIES

GENERAL PROVISIONS

4.1. The instructions in this section apply to the design of railways of I-IV categories, highways of I-IV, IIIp and IVp categories, subways, high-speed city roads and main streets running in areas with seismicity of 7, 8 and 9 points.

Notes: 1. Production, auxiliary, warehouse and other buildings for transport purposes should be designed according to the instructions in sections 2 and 3.

2. When designing structures on railways V category and on railway tracks industrial enterprises Seismic loads may be taken into account in agreement with the organization approving the project.

4.2. This section establishes special requirements for the design of transport structures with a design seismicity of 7, 8 and 9 points. The calculated seismicity for transport structures is determined according to the instructions in paragraph 4.3.

4.3. Projects for tunnels and bridges with a length of more than 500 m should be developed based on the calculated seismicity, established in agreement with the organization approving the project, taking into account data from special engineering and seismological studies.

The calculated seismicity for tunnels and bridges with a length of no more than 500 m and other artificial structures on railways and highways of categories I-III, as well as on high-speed city roads and main streets is assumed to be equal to the seismicity of construction sites, but not more than 9 points.

The calculated seismicity for artificial structures on railways of IV-V categories, on railway tracks of industrial enterprises and on roads of IV, IIIï and IVï categories, as well as for embankments, excavations, ventilation and drainage tunnels on roads of all categories is taken as one point lower than seismicity construction sites.

Note: The seismicity of construction sites for tunnels and bridges not exceeding 500 m in length and other artificial road structures, as well as the seismicity of embankment and excavation construction sites, as a rule, should be determined on the basis of data from general engineering and geological surveys according to table 1* taking into account additional requirements, set out in clause 4.4.

4.4. During surveys for the construction of transport structures erected on sites with special engineering-geological conditions (sites with complex terrain and geology, river beds and floodplains, underground workings, etc.), and when designing these structures, coarse, low-moisture soils from igneous rocks containing 30% of sand-clay filler, as well as dense gravelly and medium-density water-saturated sands, should be classified as category II soils according to seismic properties; clay soils with a consistency index of 0.25< IL£ 0.5 at porosity factor e< 0.9 for clays and loams and e < 0,7 для супесей - к грунтам III категории.

Notes. The seismicity of tunnel construction sites should be determined depending on the seismic properties of the soil in which the tunnel is embedded.

2. The seismicity of construction sites for bridge supports and retaining walls with shallow foundations should be determined depending on the seismic properties of the soil located at the foundation marks.

3. The seismicity of construction sites for bridge supports with deep foundations, as a rule, should be determined depending on the seismic properties of the soil of the upper 10-meter layer, counting from the natural surface of the soil, and when cutting the soil - from the surface of the soil after cutting. In cases where the calculation of a structure takes into account the inertial forces of the soil masses cut through by the foundation, the seismicity of the construction site is established depending on the seismic properties of the soil located at the foundation marks.

4. The seismicity of construction sites for embankments and pipes under embankments should be determined depending on the seismic properties of the soil of the upper 10-meter layer of the embankment base.

5. The seismicity of excavation construction sites can be determined depending on the seismic properties of the soil of a 10-meter layer, counting from the contour of the excavation slopes.

ROAD ROUTING

4.5. When tracing roads in areas with seismicity of 7, 8 and 9 points, as a rule, it is necessary to avoid areas that are particularly unfavorable in engineering and geological terms, in particular areas of possible landslides, landslides and avalanches.

4.6. The routing of roads in areas with seismicity of 8 and 9 points on non-rocky slopes with a slope steepness of more than 1:1.5 is allowed only on the basis of the results of special engineering-geological surveys. Routing roads along non-rocky slopes with a steepness of 1:1 or more is not allowed.

SUBSTRATE AND UPPER STRUCTURE OF THE WAY

4.7. When the calculated seismicity is 9 points and the height of the embankments (depth of excavations) is more than 4 m, the slopes of the subgrade made of non-rocky soils should be taken at 1:0.25 position of the slopes designed for non-seismic areas. Slopes with a steepness of 1:2.25 and less steep can be designed according to the standards for non-seismic areas.

Slopes of excavations and half-excavations located in rocky soils, as well as slopes of embankments made of coarse-grained soils containing less than 20% by weight of filler, can be designed according to the standards for non-seismic areas.

7.87 For laying brick (stone) walls, a single-row chain ligation system should be used. On sites with a seismicity of 7 points, the use of a multi-row ligation system is allowed, while the bonded rows of masonry must be arranged at least after three spoon rows.

7.88 In seismic areas, the use of lightweight masonry with internal heat-insulating layers in load-bearing and self-supporting walls is not allowed.

7.89 For laying load-bearing and self-supporting walls, the following products and materials should be used:

Burnt solid or hollow brick of grade 75 and higher with vertical holes with a diameter of no more than 16 mm and a voidness of no more than 25%;

Ceramic stones of grade no lower than 100 with vertical holes with a diameter of no more than 16 mm and a voidness of no more than 25%;

Solid concrete stones and small blocks of heavy and light concrete of class not lower than B3.5;

If the seismicity of the construction site is 7 points, it is allowed to use ceramic stones of a grade not lower than 75 with vertical slot voids up to 12 mm wide and a voidness of no more than 25%.

The walls must be laid using mixed cement mortars of grade no lower than 50.

7.90 Use of stones and small blocks of regular shape in the masonry of load-bearing and self-supporting walls natural materials(shell rocks, limestones, tuffs, sandstones), hollow concrete stones and blocks, solid blocks of cellular concrete of class below B3.5, bricks and stones made using non-firing technology, must be carried out in accordance with regulatory and instructional documents developed in the development of these standards .

7.91 Making brick (stone) masonry of load-bearing and self-supporting walls (including those reinforced with reinforcement or reinforced concrete inclusions) at negative temperatures when the seismicity of construction sites is 9 and 10 points is prohibited.

If the seismicity of construction sites is 7 and 8 points, winter masonry is allowed with the mandatory inclusion of additives in the mortar that ensure hardening of the mortar at subzero temperatures.

7.92 In seismic areas, the use of baked brick or ceramic stone with horizontal (parallel to the masonry bed) voids is not allowed.

7.93 Value of temporary resistance of brick (stone) masonry to axial tension along untied seams (normal adhesion - Rnt) for load-bearing and self-supporting walls must be at least 120 kPa (1.2 kgf/cm2).

To increase the normal adhesion of masonry, solutions with special additives should be used.

7.94 The values ​​of the design resistance of masonry (axial tension), (shear) and (flexural tension) along tied seams should be taken in accordance with the instructions of building codes for the design of masonry and reinforced masonry structures, and for untied seams - determined using formulas (7.1-7.3) depending on the value obtained during tests carried out in the construction area:

The values ​​of , and should not exceed the corresponding values ​​obtained when destroying brick or stone masonry.

7.95 The required value should be assigned depending on the test results of brick (stone) masonry in the construction area and indicated in the project.

If it is impossible to obtain the value at the construction site , equal to or exceeding 120 kPa (1.2 kgf/cm2), the use of brick or stone masonry for the construction of load-bearing and self-supporting walls is not allowed.

7.96 When constructing buildings in seismic areas, control tests should be carried out to determine the actual value of the normal adhesion of the masonry. The construction of buildings with load-bearing and self-supporting brick (stone) walls without carrying out control tests of the masonry is not allowed.

7.97 In the levels of floors and coverings of brick buildings, anti-seismic belts made of monolithic reinforced concrete with continuous reinforcement should be installed along all longitudinal and transverse load-bearing walls.

In buildings with monolithic reinforced concrete floors embedded along the contour into the walls, it is allowed not to install anti-seismic belts at the floor level. In this case, the length of the part of monolithic reinforced concrete floors and coverings resting on brick walls must be at least 250 mm.

7.98 Anti-seismic belts and monolithic reinforced concrete floors of the upper floor of the building must be connected to the masonry by vertical reinforcement outlets or reinforced concrete connections.

7.99 The anti-seismic belt must have an area for supporting the ceiling and be installed across the entire width of the wall. In external walls with a thickness of 510 mm or more, the width of the belt can be less than the thickness of the wall by up to 150 mm. The height of the belt must be at least 150 mm, concrete class not lower than B12.5. Anti-seismic belts are reinforced with spatial frames with longitudinal reinforcement of at least 4Ø10 when the seismicity of construction sites is 7 and 8 points and at least 4Ø12 when the seismicity of construction sites is 9 and 10 points.

7.100 At the junctions of load-bearing walls, reinforcing mesh with a total cross-sectional area of ​​longitudinal reinforcement of at least 1 cm 2, a length of at least 150 cm must be placed in the masonry every 700 mm in height when the seismicity of the construction site is 7 and 8 points and every 500 mm when the seismicity of the construction sites is 9 and 10 points.

7.101 The seismic resistance of brick (stone) walls of buildings should be increased:

Reinforcement meshes laid in horizontal masonry joints;

Creating a complex structure by reinforcing walls with vertical meshes of reinforcement in a layer of shotcrete of a class not lower than B7.5 or in a layer of cement-sand mortar of a grade not lower than 100;

Creating a complex structure by including monolithic vertical and horizontal reinforced concrete elements into the masonry;

The installation of an internal reinforced concrete layer in the masonry (three-layer monolithic stone masonry).

To improve seismic resistance brick walls It is allowed to use other experimentally proven methods.

7.102 When designing complex structures in the form of walls reinforced with mesh reinforcement in a layer of shotcrete or in a layer of cement-sand mortar:

Grids are usually installed on both sides of the walls;

The thickness of the layers of concrete or mortar must be at least 40 mm on each side of the wall;

Fastening of reinforcing mesh to the walls is carried out with anchors made of reinforcement with a diameter of at least 6 mm, which are installed in a checkerboard pattern with a pitch of no more than 600 mm.

When reinforcing walls using this method, technological measures should be taken to ensure reliable adhesion of layers of concrete or mortar to the masonry.

7.103 Reinforced concrete inclusions in masonry of a complex structure must be open on at least one side.

Vertical reinforced concrete inclusions (cores) must be connected to anti-seismic belts. Horizontal reinforcement of walls and anti-seismic belts should be passed through vertical reinforced concrete inclusions.

Cores should be installed in places where walls meet, along the edges of window and door openings, on blind sections of walls with a step not exceeding the height of the floor. Concrete cores must be at least class B15.

7.104 The internal reinforced concrete layer of three-layer monolithic masonry must be made of concrete of class not lower than B10 and have a thickness of at least 100 mm.

The outer layers of monolithic masonry (brick) must be connected to each other by horizontal reinforcement, installed in increments of no more than 600 mm and passed through the inner layer of concrete.

Floors and coverings must rest on the internal reinforced concrete layer of monolithic masonry or on an anti-seismic belt.

7.105 The height of the floor of buildings with load-bearing walls made of brickwork, not reinforced with reinforcement or reinforced only with horizontal reinforcing mesh, should not exceed 5.0 for seismicity of 7, 8 and 9 points, respectively; 4.0 and 3.5 m. In this case, the ratio of the floor height to the wall thickness should be no more than 12.

The height of the floor of buildings with walls of a complex structure or of monolithic masonry can be taken with seismicity of 7, 8, 9 and 10 points, respectively 6.0; 5.0; 4.5 and 4.0 m.

7.106 In buildings with load-bearing brick walls, in addition to external longitudinal walls, as a rule, there must be at least one internal longitudinal wall connected to the end external and internal transverse walls. The transverse load-bearing walls of staircases must extend across the entire width of the building.

7.107 The distances between the axes of transverse walls or frames replacing them must be checked by calculation and be no more than the values ​​​​given in Table 7.4.

Table 7.4

7.108 The dimensions of brick wall elements should be determined by calculation. For brickwork without reinforcement or with reinforcement in the form of horizontal reinforcement in the joints, the requirements given in Table 7.5 must also be met.

Table 7.5

7.109 Door and window openings in the brick walls of staircases with a seismicity of 8 or more points must have a reinforced concrete frame.

7.110 Staircase landings and landing beams should be embedded in the masonry to a depth of at least 250 mm and anchored. Elements of prefabricated stairs (steps, stringers, prefabricated flights) must be secured.

The installation of cantilever steps embedded in the masonry of staircase walls is not permitted.

7.111 The removal of balconies in buildings with stone walls and prefabricated floors should not exceed 1.5 m.

7.112 Sections of walls and pillars above the attic floor, having a height of more than 400 mm, must be reinforced or strengthened with monolithic reinforced concrete inclusions anchored in an anti-seismic belt.

7.113 Lintels should, as a rule, be installed over the entire thickness of the wall and embedded in the masonry to a depth of at least 350 mm. With an opening width of up to 1.5 m, sealing of lintels is allowed at 250 mm.

In seismic areas, the use of prefabricated timber lintels is not allowed.

7.114 Load-bearing walls in which they are located ventilation ducts and chimneys should be designed as an integrated structure.

Within the building plan or compartment, it is not allowed to change the direction of layout of reinforced concrete slabs of prefabricated floors (coverings) made in accordance with 7.23 (1, 2).

7.115 Self-supporting walls must have connections with the frame that do not prevent horizontal displacements of the frame along the walls. A gap of at least 20 mm must be provided between the surface of the walls and the columns of the frame.

Along the entire length of a self-supporting wall made of brick (stone) masonry, at the level of floor slabs (coverings) or the top of window openings, anti-seismic belts must be installed, connected by flexible connections to the building frame. At the intersection of end and longitudinal walls, anti-seismic joints should be installed along the entire height of the walls.

7.116 The strength of self-supporting wall structures and their fastenings should be checked by calculations performed in accordance with 5.21. Seismic forces acting in the plane of self-supporting walls must be absorbed by the walls themselves.

For laying brick (stone) walls, a single-row chain ligation system should be used. On sites with a seismicity of 7 points, the use of a multi-row ligation system is allowed, while the bonded rows of masonry must be arranged at least after three spoon rows.

In seismic areas, the use of lightweight masonry with internal heat-insulating layers in load-bearing and self-supporting walls is not allowed.

For laying load-bearing and self-supporting walls, the following products and materials should be used:

a) fired solid or hollow brick of grade 75 and higher with vertical holes with a diameter of no more than 16 mm and a voidness of no more than 25%;

b) ceramic stones of grade no lower than 100 with vertical holes with a diameter of no more than 16 mm and a voidness of no more than 25%;

c) solid concrete stones and small blocks of heavy and light concrete of class not lower than B3.5;

d) if the seismicity of the construction site is 7 points, it is allowed to use ceramic stones of a grade not lower than 75 with vertical slot voids up to 12 mm wide and a voidness of no more than 25%.

The walls must be laid using mixed cement mortars of grade no lower than 50.

The use of stones and small blocks of regular shape from natural materials (shell rocks, limestones, tuffs, sandstones), hollow concrete stones and blocks, solid blocks of cellular concrete of class below B3.5, bricks and stones, in the masonry of load-bearing and self-supporting walls
manufactured using non-firing technology must be carried out in accordance with regulatory and instructional documents developed in the development of these standards.

The construction of load-bearing and self-supporting walls (including those reinforced with reinforcement or reinforced concrete inclusions) at negative temperatures in brick (stone) masonry when the seismicity of construction sites is 9 and 10 points is prohibited.

If the seismicity of construction sites is 7 and 8 points, winter masonry is allowed with the mandatory inclusion of additives in the mortar that ensure hardening of the mortar at subzero temperatures.

In seismic areas, the use of baked brick or ceramic stone with horizontal (parallel to the masonry bed) voids is not allowed.

The value of the temporary resistance of brick (stone) masonry to axial tension along untied seams (normal adhesion - Rnl) for load-bearing and self-supporting walls it must be at least 120 kPa (1.2 kgf/cm2).

To increase the normal adhesion of masonry, solutions with special additives should be used.

Design resistance values ​​for masonry Rtl(axial tension), R(slice) and Rnl(tension during bending) along tied seams should be taken in accordance with the instructions of building codes for the design of stone and reinforced masonry structures, and for untied seams - determined according to formulas (7.1-7.3) SNiP RK 2.03-30-2006, depending on the value Rnt obtained during tests carried out in the construction area:

R =0.45Rnt (7.1)

R sq =0.7R nt (7.2)

Rtb =0.8Rnt (7.3)

Values R f R sq And Rtb should not exceed the corresponding values ​​obtained when destroying brick or stone masonry.

Required value Rni should be assigned depending on the test results of brick (stone) masonry in the construction area and indicated in the project.

If it is impossible to obtain the value at the construction site Rnt equal to or exceeding 120 kPa (1.2 kgf/cm 2), the use of brick or stone masonry for the construction of load-bearing and self-supporting walls is not allowed.

When constructing buildings in seismic areas, control tests should be carried out to determine the actual value of the normal adhesion of the masonry. Construction
buildings with load-bearing and self-supporting brick (stone) walls are not allowed without carrying out control tests of the masonry.

In the levels of floors and coverings of brick buildings, anti-seismic belts made of monolithic reinforced concrete with continuous reinforcement should be installed along all longitudinal and transverse load-bearing walls.

In buildings with monolithic reinforced concrete floors embedded along the contour into the walls, it is allowed not to install anti-seismic belts at the floor level. In this case, the length of the part of monolithic reinforced concrete floors and coverings resting on brick walls must be at least 250 mm.

Anti-seismic belts and monolithic reinforced concrete floors of the upper floor of the building must be connected to the masonry by vertical outlets of reinforcement or reinforced concrete
connections.

The anti-seismic belt must have a zone for supporting the ceiling and be installed across the entire width of the wall. In external walls with a thickness of 510 mm or more, the width of the belt can be less than the thickness of the wall by up to 150 mm. The height of the belt must be at least 150 mm, concrete class not lower than B12.5. Anti-seismic belts are reinforced with spatial frames with longitudinal reinforcement of at least 4Ø10 when the seismicity of construction sites is 7 and 8 points and at least 4Ø12 when the seismicity of construction sites is 9 and 10 points.

At the junctions of load-bearing walls, reinforcing meshes with a total cross-sectional area of ​​longitudinal reinforcement of at least 1 cm 2 and a length of at least 150 cm must be placed in the masonry every 700 mm in height if the seismicity of the construction site is 7 and 8 points and after 500 mm if the seismicity of the construction sites is 9 and 10 points.

The internal reinforced concrete layer of three-layer monolithic masonry must be made of concrete of class not lower than B10 and have a thickness of at least 100 mm.

The outer layers of monolithic masonry (brick) must be connected to each other by horizontal reinforcement, installed in increments of no more than 600 mm and passed through the inner layer of concrete.

Floors and coverings must rest on the internal reinforced concrete layer of monolithic masonry or on an anti-seismic belt.

The height of the floor of buildings with load-bearing walls made of brickwork, not reinforced with reinforcement or reinforced only with horizontal reinforcing mesh, should not exceed 5.0 for seismicity of 7, 8 and 9 points, respectively; 4.0 and 3.5 m. In this case, the ratio of floor height to
The wall thickness should be no more than 12.

The height of the floor of buildings with walls of a complex structure or of monolithic masonry can be taken with seismicity of 7, 8, 9 and 10 points, respectively 6.0; 5.0; 4.5 and 4.0 m.

In buildings with load-bearing brick walls, in addition to external longitudinal walls, as a rule, there must be at least one internal longitudinal wall connected to the end external and internal transverse walls. The transverse load-bearing walls of staircases must extend across the entire width of the building.

The distances between the axes of transverse walls or frames replacing them must be checked by calculation and be no more than the values ​​​​given in the table. 7.4 SNiP RK 2.03-30-2006.

The dimensions of brick wall elements should be determined by calculation. For brickwork without reinforcement or with reinforcement in the form of horizontal reinforcement in the joints, the requirements given in Table 1 must also be met. 7.5 SNiP RK 2.03-30-2006.

Door and window openings in the brick walls of staircases with seismicity of 8 points or more must have reinforced concrete frames.

Stair landings and stair landing beams should be embedded in the masonry to a depth of at least 250 mm and anchored. Elements of prefabricated stairs (steps, stringers, prefabricated flights) must be secured.

The installation of cantilever steps embedded in the masonry of staircase walls is not allowed

The extension of balconies in buildings with stone walls and prefabricated floors should not exceed 1.5 m.

Sections of walls and pillars above the attic floor, having a height of more than 400 mm, must be reinforced or reinforced with monolithic reinforced concrete inclusions anchored in an anti-seismic belt.

Lintels should, as a rule, be installed over the entire thickness of the wall and embedded in the masonry to a depth of at least 350 mm. With opening width before 1.5 m sealing of jumpers is allowed
by 250 mm.

In seismic areas, the use of prefabricated timber lintels is not allowed.

Load-bearing walls housing ventilation ducts and chimneys should be designed as a complex structure.

Within the plan of a building or compartment, it is not allowed to change the direction of layout of reinforced concrete slabs of prefabricated floors (coverings) made in accordance with paragraphs 7.23.a, b of SNiP RK 2.03-30-2006.

Self-supporting walls must have connections with the frame that do not prevent horizontal displacements of the frame along the walls. A gap of at least 20 mm must be provided between the surface of the walls and the columns of the frame.

Along the entire length of a self-supporting wall made of brick (stone) masonry, at the level of floor slabs (coverings) or the top of window openings, anti-seismic belts must be installed, connected by flexible connections to the building frame. At the intersection of end and longitudinal walls, anti-seismic joints should be installed along the entire height of the walls.

The strength of self-supporting wall structures and their fastenings should be checked by calculation performed in accordance with clause 5.21. Seismic forces acting in the plane of self-supporting walls must be absorbed by the walls themselves.

Lecture topic 21. Basic principles of earthquake resistance design for masonry buildings (continuation of lecture topic 20)

Lecture outline

· Complex designs. The rule for horizontal and vertical reinforcement of complex structures.

· Features of calculation of complex structures.

Lecture abstracts

1. Methods for increasing the seismic resistance of brick (stone) walls. Standard requirements for the installation of vertical reinforced concrete cores in blank walls, as well as in walls with openings. Requirement of standards for strengthening load-bearing walls in which ventilation ducts and chimneys are located.

Main content of the lecture

The seismic resistance of brick (stone) walls of buildings should be increased:

· mesh made of reinforcement, laid in horizontal joints of the masonry;

· creating a complex structure by reinforcing walls with vertical meshes of reinforcement in a layer of shotcrete of a class not lower than B7.5 or in a layer of cement-sand mortar of a grade not lower than 100;

· creating a complex structure by including monolithic vertical and horizontal reinforced concrete elements into the masonry;

· installation of an internal reinforced concrete layer in the masonry (three-layer monolithic masonry).

To increase the seismic resistance of brick walls, it is allowed to use other experimentally proven methods.

When designing complex structures in the form of walls reinforced with mesh reinforcement in a layer of shotcrete or in a layer of cement-sand mortar:

grids are usually installed on both sides of the walls;

The thickness of the layers of concrete or mortar must be at least 40 mm on each side of the wall;

The reinforcement mesh is fastened to the walls using reinforcement anchors with a diameter of at least 6 mm, which are installed in a checkerboard pattern with a pitch of no more than 600 mm.

When reinforcing walls using this method, technological measures should be taken to ensure reliable adhesion of layers of concrete or mortar to the masonry.

Reinforced concrete inclusions in masonry of a complex structure must be open on at least one side.

Vertical reinforced concrete inclusions (cores) must be connected to anti-seismic belts. Horizontal reinforcement of walls and anti-seismic belts should be passed through vertical reinforced concrete inclusions.

Cores should be installed at the junctions of walls, at the edges of windows and doors

openings, on blind sections of walls with a step not exceeding the height of the floor. Concrete cores must be at least class B15.

Lecture 22

Lecture topic 22. Principles of ensuring seismic resistance of single-story buildings industrial buildings from reinforced concrete prefabricated structures

Lecture outline

· Load-bearing structures of one-story industrial buildings. Reinforced concrete prefabricated structures.

· One-story industrial buildings not equipped with overhead cranes. Measures to ensure seismic resistance of one-story industrial buildings not equipped with overhead cranes.

· One-story industrial buildings equipped with overhead cranes. Measures to ensure seismic resistance of one-story industrial buildings.

Lecture abstracts

1. Structural diagrams one-story industrial buildings. Structural diagrams of a building in the form of a transverse frame of racks, clamped in the foundations and hinged to the roof crossbars.

2. Vertical connections along columns in one-story industrial buildings equipped with overhead cranes. The use of prefabricated reinforced concrete rafter and sub-rafter structures in buildings with a calculated seismicity of 7, 8 and 9 points.

3. Providing hard drive covering building with prefabricated reinforced concrete structures coverings. Requirements of earthquake-resistant construction standards.

Main content of the lecture

Lecture 23.

Lecture topic 23. Principles of ensuring seismic resistance of one-story industrial buildings made of reinforced concrete prefabricated structures (continued)

Lecture outline

· Coverings of frame buildings.

· Walls in frame buildings.

· Requirements for earthquake-resistant construction.

Lecture abstracts

1. Structural schemes of frame one-story buildings: combined, in which a frame scheme is adopted in one direction of the building, and a braced one in the other; in the form of racks, pinched in the foundations and hingedly connected to the rafter structures; in the form of spatial frame structures hingedly connected to the foundations.

2. Conditions for ensuring separate operation of load-bearing and non-load-bearing structures (except for hanging systems). Conditions for ensuring separate operation of load-bearing structures and hanging systems.

3. Conditions for ensuring the rigidity of the coating disk industrial building using prefabricated reinforced concrete slabs.

Main content of the lecture

Lecture 24.

Lecture topic 24. Principles for ensuring seismic resistance of multi-storey large-panel buildings

Lecture outline

· Large-panel structures of multi-storey buildings.

· Ceilings and coverings of large-panel buildings.

· Walls in large-panel buildings.

· General principles design of large-panel buildings.

Lecture abstracts

1. Principles of ensuring seismic resistance of inter-storey large-panel buildings. Structural and planning cell in large-panel buildings depending on the pitch of the transverse walls.

2. Connections of wall and ceiling panels. Requirements for the class of concrete for embedding joints of wall and ceiling panels. Standard requirements for the intended thickness of single-layer wall panels and the thickness of the internal load-bearing layer of multi-layer panels.

3. Reinforcement of wall panels. Structural requirements for reinforcement of wall panels. Vertical reinforcement along the contour of window and door openings. A structural requirement of standards for the purpose of the cross-sectional area of ​​vertical reinforcement installed at the edges of window and door openings.

Main content of the lecture