Waterproofing
Brickwork - in earthquake-prone areas. Buildings with load-bearing and self-supporting walls made of brick (stone) masonry Control of work during brickwork of walls

Brickwork - in earthquake-prone areas. Buildings with load-bearing and self-supporting walls made of brick (stone) masonry Control of work during brickwork of walls

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Course project - universal workshop (Course paper)

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In the production of brickwork in seismic areas increased demands should be placed on the quality of the stone wall materials and mortar used. The surfaces of stone, brick or block must be cleaned of dust before laying. In mortars intended for the construction of masonry, Portland cement should be used as a binder.

Before the start of masonry work, the construction laboratory determines the optimal relationship between the amount of pre-wetting of 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.

Masonry of bricks and ceramic slotted stones is carried out in compliance with the following additional requirements: masonry of stone structures is erected to the full thickness of the structures in each row; horizontal, vertical, transverse and longitudinal joints of the masonry are filled completely with mortar with cutting of the mortar on the outer sides of the masonry; masonry walls in places of mutual abutment are erected simultaneously; The bonded rows of masonry, including backfill, are laid out of whole stone and brick; temporary (assembly) breaks in the masonry being erected end with an inclined groove and are located outside the places of structural reinforcement of the walls.

When reinforcing brickwork (pillars), it is necessary to ensure that the thickness of the seams in which the reinforcement is located exceeds the diameter of the reinforcement by at least 4 mm, while maintaining the average thickness of the seam for a given masonry. The diameter of the wire of the transverse mesh for masonry reinforcement is allowed to be no less than 3 and no more than 8 mm. When the wire diameter is more than 5 mm, a zigzag mesh should be used. The use of individual rods (laid mutually perpendicular in adjacent seams) instead of knitted or welded rectangular mesh or zigzag mesh is prohibited.

To control the placement of reinforcement when mesh reinforcement of pillars and piers, the ends of individual rods (at least two) in each mesh should be released from the horizontal joints of the masonry by 2-3 mm.

During the masonry process, the builder or craftsman must ensure that the methods of securing purlins, beams, decks and floor panels in walls and posts are consistent with the design. The ends of split purlins and beams resting on internal walls and pillars must be connected and embedded in the masonry; According to the design, reinforced concrete or metal pads are laid under the ends of the purlins and beams.

When laying ordinary or wedge lintels, you should use only selected whole bricks and use a mortar of grade 25 and higher. The lintels are embedded in the walls at a distance of at least 25 cm from the slope of the opening. Under the bottom row of bricks, stacked iron or steel wire with a diameter of 4–6 mm is placed in a layer of mortar at the rate of one rod with a cross-section of 0.2 cm 2 for each part of the lintel half a brick thick, unless the design provides for stronger reinforcement.

When laying a cornice, the overhang of each row should not exceed 1/3 of the length of the brick, and the total extension of the cornice should not exceed half the thickness of the wall. Cornices with a large offset should be reinforced or made on reinforced concrete slabs, etc., strengthening them with anchors embedded in the masonry.

Brickwork of walls must be carried out in accordance with the requirements of SNiP III-17-78. During the production of brickwork, acceptance is carried out according to the hidden work report. Hidden work subject to acceptance includes: completed waterproofing; installed fittings; areas of masonry in places where purlins and beams support; installation of embedded parts - connections, anchors, etc.; fastening cornices and balconies; protection against corrosion of steel elements and parts embedded in masonry; sealing the ends of purlins and beams in walls and pillars (presence of support plates, anchors and other necessary parts); sedimentary joints; supporting floor slabs on walls, etc.
Control of stone work production in winter

The main method of producing brickwork in winter conditions is freezing. Masonry in this way is carried out in the open air using cold bricks and heated mortar, while freezing of the mortar is allowed some time after it has been compressed with brick.

Electric heating of winter masonry has not found widespread use. Masonry in greenhouses is used as an exception when constructing foundations or basement walls made of rubble concrete. Masonry using quick-hardening mortars prepared using a mixture of Portland cement and aluminous cement is rarely used in construction practice due to the scarcity of aluminous cement. Mortars with added sodium chloride or calcium are not used for laying walls of residential buildings, as they cause increased humidity in buildings. Currently, chemical additives are used for construction mortars - sodium nitrite, potash and complex chemical additives - calcium nitrite with urea (NKM - finished product), etc. In this case, the grade of mortar is assigned 50 and higher.

When monitoring the construction of masonry using the freezing method, it should be taken into account that early freezing of mortars in the joints leads to a change in the properties of brickwork compared to wall masonry in the summer. The strength and stability of winter masonry decreases sharply during the thawing period. The mason foreman must ensure that the brick is cleared of snow and ice before laying. Cement, cement-lime or cement-clay mortars are used for masonry. The brand of mortar must be assigned in accordance with the recommendations of the project, as well as taking into account the outside air temperature: with an average daily air temperature of up to -3°C - a mortar of the same brand as for summer masonry; at temperatures from –4 to –20°C – the grade of solution increases by one; at temperatures below –20°C – by two.

During bricklaying using the freezing method, the temperature of the mortar when used depends on the outside air temperature, as shown in Table. 1.37.

Table 1.37

Outside air temperature, °С up to –10 From –11 to –20 Below –20 Solution temperature, °С 101520

Solutions should be prepared on insulated mortar units using hot water (up to 80°C) and heated sand (not higher than 60°C). To reduce the freezing point of the solution, it is recommended to add sodium nitrite to its composition in an amount of 5% by weight of the mixing water.

At the workplace, the solution should be stored in insulated boxes with lids, and at air temperatures below –10°C, it should be heated through the bottom and walls of the supply boxes using tubular electric heaters. Warm up frozen or frozen solution hot water and it is prohibited to use it.

When performing the laying using the pressing method, it is recommended to spread the mortar for no more than every two verst bricks or for 6–8 bricks for backfilling. The thickness of horizontal joints is no more than 12 mm, since with a greater thickness, severe settlement of the walls is possible during the spring thawing period. The masonry is carried out in complete horizontal rows, that is, without preliminary laying the outer verst, to the height of several rows.

The speed of laying bricks in winter should be high enough so that the mortar in the underlying layers of masonry is compacted by the overlying rows before freezing. Therefore, more workers must work at each capture than in the summer. By break in work, vertical joints should be filled with mortar. During breaks, it is recommended to cover the masonry with roofing felt or plywood; When resuming work, the top layer of masonry should be thoroughly cleared of snow and ice.

Freezing masonry in spring can give a large and uneven settlement, therefore, clearances of at least 5 mm should be left above window and door frames installed in the walls. Settlement joints must be made in places where walls more than 4 m high, erected in winter, adjoin walls of summer masonry, and old structures. Lintels over openings in walls are usually made of precast reinforced concrete elements. For spans of less than 1.5 m, it is allowed to install ordinary brick lintels, and the formwork can be removed no earlier than after 15 days. after complete thawing of the masonry.

After erecting walls and pillars within a floor, the foreman must ensure that prefabricated floor elements are immediately laid. The ends of the beams and purlins, resting on the walls, are fastened after 2–3 m to the wall masonry with metal ties secured in the vertical longitudinal joints of the masonry. The ends of split purlins or flooring slabs resting on pillars or a longitudinal wall are tied with pads or anchors.

To give brickwork, erected using the freezing method, the required stability in the corners of external walls and at junctions interior walls steel connections are laid to the outer ones. The ties must be inserted into each of the adjacent walls by 1–1.5 m and terminated at the ends with anchors. In buildings with a height of 7 or more floors, steel ties are laid at the floor level of each floor, in buildings with fewer floors - at the floor level of the second, fourth and each overlying floor.

In some cases, the freezing method is combined with heating the constructed building by isolating it from outside air and connecting a heating system or installing special air heating devices. As a result of this, the temperature of the internal air rises, the brickwork thaws, the mortar in it hardens, then the masonry dries and interior finishing work can begin.

When the outside air temperature is positive, the masonry thaws. During this period, its strength and stability sharply decrease and settlement increases. The workman and the foreman must monitor the magnitude, direction and degree of uniformity of the masonry settlement. When thawing the masonry, the workman must personally check the condition of all stressed areas of the masonry, and also ensure that previously left nests, grooves and other holes have been filled. With the onset of thaws, random loads (for example, remnants of building materials) should be removed from the floors.

During the entire thawing period, masonry made using the freezing method must be carefully monitored and measures must be taken to ensure the stability of the erected structures. If signs of overstress are detected (cracks, uneven settlements), measures should be taken immediately to reduce the load. In such cases, as a rule, temporary unloading racks are installed under the ends of load-bearing elements (for example, ceilings, lintels). Temporary racks in multi-story buildings are installed not only in the unloaded span or masonry opening, but also in all underlying floors in order to avoid overloading the latter.

If a deviation of thawing walls and pillars from the vertical or cracks are detected at the junction of the transverse walls with the longitudinal ones, in addition to temporary fastenings, struts and braces are immediately installed to eliminate the possibility of the development of displacements. In case of significant displacements, tension ropes, compressions, and struts are installed to bring the displaced elements into the design position. This should be done before the mortar in the joints hardens, usually no later than five days after the masonry begins to thaw.

To increase the load-bearing capacity of brick walls and ensure the spatial rigidity of the entire building in the spring, artificial thawing of the masonry is used, which is carried out by heating the building with closed openings in the walls and ceilings, which can be recommended for buildings to be finished before spring warming. In addition, artificial thawing is used for load-bearing brick walls with solid monolithic reinforced concrete floors, supported along the perimeter by these walls, and inside by reinforced concrete or metal columns of constant height. For artificial thawing, portable oil and gas heaters can be used, with the help of which the temperature in the rooms is raised to 30–50°C and maintained for 3-5 days. Then within 5–10 days. at a temperature of 20–25°C and increased ventilation, dry the walls. After this, using a stationary heating system, the walls of the building are dried until the moisture content of the solution is no more than 8%, and only then they begin finishing work. By the end of heating, the strength of the mortar in the masonry should be at least 20% of the brand strength.

During the spring thawing period, the construction laboratory must systematically monitor the increase in strength of the winter masonry mortar. In accordance with the instructions of the designer's supervision, in several places of the brickwork, the laboratory technician selects sample plates measuring at least 50x50 mm from horizontal joints. It is best to take them under window openings; To do this, remove two rows of bricks and, using a special spatula or trowel, separate the mortar plate from the brick.

The samples, along with the accompanying certificate, are sent to the construction laboratory for testing. The accompanying act indicates the number of floors and structure of the building, the thickness of the walls and the position of the sampling site, as well as the time of work, the date of sampling and the design brand of mortar. Samples of winter frozen solutions intended to determine the strength at the time of thawing are stored at subzero temperatures.

From the solution samples delivered to the laboratory, cube samples with an edge of 20–40 mm are made or, according to the engineer Senyuta’s method, plates in the form of a square, the sides of which are approximately 1.5 times the thickness of the plate, equal to the thickness of the seam. To obtain cubes, two plates are glued together with a thin layer of gypsum, which is also used to level the supporting surface of the cube sample when testing mortar from summer masonry joints.

The strength of winter masonry mortars at the time of thawing is determined by a compression test, leveling the surfaces of the plates instead of a gypsum test by friction with a carborundum block, rasp, etc. Testing of samples in this case should be carried out after thawing the solution for 2 hours in the laboratory at a temperature of 18–20°C. The load on the plate is transferred through a 20–40 mm metal rod installed in the middle. The sides of the base or the diameter of the rod should be approximately equal to the thickness of the plate. Taking into account deviations in the thickness of the plates, it is recommended to have a set of rods with different sections and diameters during testing.

The compressive strength of a solution is determined by dividing the breaking load by the cross-sectional area of the rod. Five samples from each sample are tested and the arithmetic mean value is determined, which is considered to be an indicator of the strength of the solution of a given sample. To go to the strength of the solution in cubes with an edge of 70.7 mm, the test results of the plates are multiplied by a factor of 0.7.

The test results of cube samples with an edge of 30-40 mm, glued together from plates and leveled with a gypsum layer 1-2 mm thick, are multiplied by a factor of 0.65, and the test results of plates also leveled with gypsum are multiplied by a factor of 0.4. For summer masonry, the indicated coefficients are taken equal to 0.8 and 0.5, respectively.

To test the strength of mortar samples, lever instruments are used that record the strength with an error of up to 0.2 MPa, as well as tensile testing machines RMP-500 and RM-50 with reverse. These mortar tests help in time to develop the necessary measures to ensure the stability of the brickwork during the period of complete thawing.
Defects in stone structures and methods for their elimination

The causes of defects in stone structures are different: uneven settlement of individual parts of buildings; design errors associated with the use of wall materials of different strength and rigidity (for example, ceramic blocks together with sand-lime bricks) that have different physical, mechanical and elastic properties; the use of wall materials that do not meet the requirements of current standards in terms of strength and frost resistance; low quality of stone work, etc. To eliminate settlements caused by the removal of soil from under the foundation, the gaps between the base and the foundation are usually filled with soil, followed by compaction with deep vibrators. In some cases, to prevent complete destruction of the masonry, cast-in reinforced concrete piles are placed under all load-bearing walls.

The combined use of ceramic facing stones and sand-lime bricks in loaded piers of multi-storey residential buildings led to cracks appearing, the lining of the piers bulged and then collapsed.

The use of bricks, the strength of which is lower than that provided for by the design, and mortar of low quality or diluted after setting, significantly reduces the strength and solidity of the masonry and can lead to deformation and collapse of stone structures.

One of the main reasons for the occurrence of defects in stone structures is the unsatisfactory quality of stone work. The most common defects in masonry are thickened seams, voids more than 2 cm deep, absence or incorrect mesh reinforcement, deviations from the design when arranging units for supporting purlins on pillars or walls, etc. The presence of voids leads to the fact that bricks in stone structures begins to work in bending, and its strength when working in bending is significantly lower than in compression. There are cases when meshes of reinforcement with a diameter of 3–4 mm provided for in the project are replaced with meshes of reinforcement with a diameter of 5–6 mm, in the belief that such a replacement will increase the load-bearing capacity of the masonry. However, in this case, the brick lies not on a bed of mortar, but on rods, so significant local crushing stresses appear in it, which lead to the appearance of large number vertical cracks.

When checking the quality of masonry with mesh reinforcement, one has to deal with facts when the meshes are not laid according to the design, with large gaps, or instead of meshes, individual rods are laid, which in no case can replace welded mesh.

In cases where cracks are found in the brickwork during inspection, it is necessary to identify and eliminate the causes that cause them, and then make sure that the deformation of the walls has ended. To fix structural settlements and control the development of cracks, geodetic instruments and instruments, string, glass and other beacons are used. If there are no ready-made beacons at the construction site, they can be made on site from building plaster. To do this, prepare a solution of a 1:1 composition (gypsum: sand) of such a consistency that when applied to the wall it does not flow. If the brick walls are plastered, then in the places where the beacons are installed, the plaster is knocked down, the joints of the masonry are cleared, cleaned of dust and washed with water. Beacons cannot be placed on uncleaned and unwashed masonry, since due to weak adhesion to it, an increase in the opening of cracks in the masonry will not be recorded. Gypsum beacons are made 5–6 cm wide and about 20 cm long. The length of the beacons is determined on site depending on the nature of the development of cracks. The thickness of the beacon is usually 10–15 mm.

Beacons are numbered and the date of installation is written on them. The observation log records: the location of the beacon, its number, installation date, and the initial width of the crack. The condition of the beacons is systematically monitored (at least once a day), and these observations are recorded in a log. If the beacon breaks, a new one is installed next to it, which is given the same number with an index. If the beacons are repeatedly deformed (ruptured), it is necessary to immediately take measures to prevent the possibility of unexpected settlements or even collapse of the structure. If three to four weeks after the installation of the beacons there is no rupture, it means that the deformation in the controlled structure has stopped and the cracks can be repaired. Individual small cracks are cleared of dirt and dust and rubbed with a cement mortar of 1:3 composition using Portland cement grades 400–500.

Larger cracks (wider than 20 mm) are repaired by dismantling part of the old masonry and replacing it with a new one. When sealing cracks in walls up to one and a half bricks thick, dismantling and sealing of masonry is carried out sequentially in separate sections for the entire thickness of the wall in the form of brick locks. If the width of the cracks is significant (more than 40 mm), then anchors or metal ties are installed to fasten the masonry.

The strength of old brick walls, as well as walls and partitions made with significant waste space, can be increased by injecting liquid mortar or cement milk into the masonry. Construction practice has shown that brick pillars as load-bearing structures are not justified: some pillars in the upper floors have a significant displacement relative to the pillars in the lower floors. When using rigid mortar, the thickness of the seams turns out to be greater than the design one, many empty seams appear and the adhesion of the mortar to the brick is insufficient, which ultimately affects the solidity of the erected pillars. In many cases it was necessary to strengthen most of the brick pillars. The most common way to strengthen them is to take them into a clip.

Depending on the degree of damage to the masonry and production capabilities, the cages can be made of cement plaster over a steel mesh, brick with steel clamps in the seams, reinforced concrete, or steel.

In cases where reinforcement must be carried out without a significant increase in the cross-sectional dimensions of the pillars, it is recommended to make the frame from cement plaster over a steel mesh. The mesh consists of a series of clamps with a pitch of 150–200 mm, interconnected by longitudinal reinforcement with a diameter of 8–10 mm. Using the mesh formed in this way, plaster is made from a cement mortar with a composition of 1:3 (by volume), 20–25 mm thick.

Brick frames are easy to implement, but their design leads to a significant increase in the cross-sectional dimensions of the reinforced elements. Clips of this type are made of brick on edge with reinforcement of masonry joints with steel clamps with a diameter of 10–12 mm.

To increase the load-bearing capacity of stone pillars, reinforced concrete clips are used. In this case, the thickness of the cage, as a rule, is 8–10 cm. Clamps and longitudinal steel reinforcement with a diameter of 10–12 mm are attached to the reinforced pillars, after which they are filled with concrete grade M100 and higher.

Reinforcing brick pillars with steel frames requires a lot of metal, but this can significantly increase their load-bearing capacity. Similar reinforcement often has to be done for the walls of the first floor in cases where the poor quality of the brickwork has led to the appearance of cracks in them.

If the adhesion of the facing layer of ceramic blocks to the brickwork is broken, general strengthening of the masonry and cladding can be undertaken by injecting seams and voids in the masonry, as well as cracks and places where the cladding is peeling off. To do this, tubes are installed in the seams between the facing ceramic stones, through which a liquid cement mortar of composition 1:3 (by volume) is supplied. It is necessary to control the amount of injected solution and the radius of its spread. The latter can be easily determined by the appearance of stains on the interior plaster of the walls.

To strengthen the cladding and protect it from sudden peeling, it can be secured with steel pins. Holes with a diameter of 25 mm are drilled in the walls at an angle of up to 30° to a depth of 25–30 cm, into which steel pins are placed in the mortar flush with the cladding. In order to avoid accidents, it is necessary to develop projects for strengthening masonry structures as soon as possible and carry out all work prescribed by the designer's supervision under the direct supervision of the work manufacturer. Upon completion, an act is drawn up to complete the work to strengthen the stone structures.
Acceptance of stone works

In the process of acceptance of stone structures, the volume and quality of work performed, compliance of structural elements with working drawings and the requirements of SNiP III-17-78 are determined.

Throughout the entire period of work, representatives of the construction organization and technical supervision of the customer carry out acceptance of hidden work and draw up appropriate reports.

When accepting stone structures, the quality of the materials used, semi-finished products and factory-made products is established according to passports, and the quality of mortars and concrete prepared during construction is determined according to laboratory tests. In cases where the stone materials used were subjected to control testing in a construction laboratory, the results of these laboratory tests must be submitted for acceptance.

During the acceptance of completed stone structures, the following is checked:

– correct transportation, thickness and filling of seams;

– verticality, horizontality and straightness of masonry surfaces and corners;

– correct arrangement of settlement and expansion joints;

– correct installation of smoke and ventilation ducts;

– presence and correct installation of embedded parts;

– quality of the surfaces of façade unplastered brick walls (evenness of color, adherence to bandaging, pattern and jointing);

– the quality of facade surfaces lined with various types of slabs and stones;

– ensuring the drainage of surface water from the building and protecting foundations and basement walls from it.

When monitoring the quality of stone structures, they carefully measure deviations in the size and position of structures from the design ones and ensure that actual deviations do not exceed the values specified in SNiP III-17-78. Permissible deviations are given in table. 1.38.

Acceptance of arches, vaults, retaining walls and other especially critical stone structures are drawn up in separate acts. If during the production of stone works, reinforcements of individual structures were carried out, then upon acceptance, working drawings of the reinforcement and a special certificate for the work performed to strengthen the stone structures are presented. When accepting stone structures completed in winter, a winter work log and reports for hidden work are presented.

Table 1.38

Permissible deviations in the sizes and positions of structures made of brick, ceramic and natural stones of regular shape, from large blocks

Permissible deviationsWallsPillarsFoundationsDeviations from the design dimensions: by thickness151030by marks of edges and floors–10–10–25by the width of the partitions–15–by the width of openings15–by the displacement of the axes of adjacent window openings10–by the displacement of the axes of structures101020Deviations of surfaces and angles of masonry from the vertical: by one floor 1010 – for the entire building 303030 Deviations of masonry rows from the horizontal per 10 m of wall length 15–30 Irregularities on the vertical surface of the masonry, discovered when applying a 2 m long lath10

Process control cards

Brickwork pillars

SNiP III-17-78, table. 8, pp. 2.10, 3.1, 3.5, 3.15

Permissible deviations: according to the marks of edges and floors – 15 mm; thickness – 10 mm. Allowed: thickness of vertical seams - 10 mm (thickness of individual vertical seams - not less than 8 and not more than 15 mm); the thickness of horizontal seams is not less than 10 and not more than 15 mm. The suture dressing system for posts is three-row.

Permissible deviations: for displacement of structure axes – 10 mm; surfaces and corners of masonry from the vertical for one floor - 10 mm, for the entire building - 30 mm; vertical surface of the masonry from the plane when applying a 2-meter lath - 5 mm.

The depth of unfilled seams (vertical only) on the front side is allowed to be no more than 10 mm. When laying pillars, it is not allowed to use individual rods instead of knitted or welded rectangular meshes or zigzag meshes.

In table 1.39 shows the operations subject to control during the construction of pillars.

Hidden works include the following: bricklaying of pillars (marking edges and floors, correct arrangement of cushions for beams, supporting beams on cushions and embedding them in masonry).

Table 1.39

Control of work during bricklaying of pillars

Operations subject to control Composition of control (what to control) Method of control Time of control Who controls and is involved in the inspection Preparatory work Quality of the base for pillars, presence of waterproofing Visually Before the start of masonry Master Quality of bricks, mortar, fittings, embedded parts Visually, measurement, check of passports and certificates Before the start of masonry Master. In case of doubt - laboratory Correctness of tying the pillars to the alignment axes Visually, a construction plumb line Before the start of masonry Foreman Brickwork of pillars Dimensions, filling and dressing of seams Folding metal meter After completing every 5 m of masonry Foreman Geometric dimensions of the section Folding metal meter During the masonry process Foreman Verticality of the masonry, unevenness on the surface Construction plumb line, strip with probe , folding metal meter At least twice on each tier Foreman Correctness of the masonry technology and dressing of seams Visually During the masonry process Foreman Compliance of the actual position of the pillars with the design one (axis).
Alignment of pillars of different floors Construction plumb line, folding metal meter During the masonry process Foreman Markings of edges and floors, correct installation of cushions for beams, support of beams on cushions and their embedding in the masonry Visually, level, folding metal meter After installation of the cushion and installation of beams Foreman, surveyor Reinforcement of masonry Correct placement of reinforcement, distance between grids along the height of the column. Diameter of rods and distance between them Folding metal meter, caliper As the reinforcement is laid Master

Brick walls

SNiP III-B.4-72, table. 8, pp. 1.9, 2.5, 2.10, 3.5

SNiP III-17-78

Permissible deviations: rows of masonry from the horizontal per 10 m length - 15 mm; surfaces and corners of masonry from the vertical: per floor - 10 mm; for the entire building - 30 mm; by displacement of the axes of adjacent window openings - 20 mm; the width of the openings is +15 mm.

Unevenness on the vertical surface is allowed when applying a two-meter strip: unplastered - 5 mm; plastered – 10 mm.

Permissible deviations: according to the marks of edges and floors – 15 mm; the width of the walls is 15 mm; by displacement of the axis of structures – 10 mm; masonry thickness – +10 mm.

Allowed: the thickness of horizontal seams is not less than 10 and not more than 15 mm; the thickness of vertical seams is 10 mm (the thickness of individual vertical seams is not less than 8 and not more than 15 mm).

When performing hollow-core masonry, the depth of joints not filled with mortar on the front side is allowed to be no more than 15 mm.

Mortar mixtures must be used before they begin to set. Dehydrated mixtures are not allowed. Adding water to set mixtures is prohibited. Mixtures that separate during transportation must be mixed before use.

If the gap in the masonry is made with a vertical groove, then structural reinforcement of three rods with a diameter of 8 mm should be placed in the seams of the masonry grooves at intervals of 2 m along the height of the masonry, including at the level of each floor. Operations subject to control when laying brick walls are listed in Table. 1.40.

Hidden works include the following: brickwork of walls (alignment of ventilation ducts and sealing of ventilation units); masonry reinforcement (correct placement of reinforcement, diameter of rods); installation of prefabricated reinforced concrete slabs, floors (supporting floors on walls, sealing, anchorage); installation of balconies (sealing, marking, slope of balconies).

Table 1.40

Control of work during brickwork of walls

Operations subject to control Composition of control (what to control) Method of control Time of control Who controls and is involved in the inspection Brickwork of walls Quality of brick, mortar, reinforcement of embedded parts External inspection, measurement, verification of passports and certificates Before the start of laying the walls of the floor Foreman. In case of doubt - laboratory Correctness of axes layout Metal tape measure, folding metal meter Before the start of masonry Foreman Horizontal marking of masonry cut-offs for the floor Level, lath, building level Before installation of floor panels Foreman, surveyor Alignment of ventilation ducts and sealing of ventilation units Visually, plumb line After completion of laying the walls of the floor Foreman Geometric dimensions of the masonry (thickness , openings)Folding metal meter, metal tape measureAfter completing every 10 m 3 masonry Master Verticality, horizontality and surface of the masonry Level of construction plumb line, construction lath In the process and after completion Master Quality of masonry seams (dimensions and filling) Visually, folding metal meter, 2-meter lath After completing the masonry The walls of the floor are every 10 m 3 mosquimaster the breakdown and the mark of the bottom of the vehicle metal, the level of the construction of the starting of the masonry, the tagging from the label + 1 m from the clean Polanialhposls of the masonry, the layout of the apartment, the masonry of the masonry the geometric sizes of the melodrama began the masonry of the wall masterarmicment Location reinforcement, diameter of the rods and etc. Visually folding metal meter Before installing reinforcement Foreman Installation of prefabricated reinforced concrete slabs, floors Supporting floors on walls, embedding, anchorage Visually folding metal meter After installation of floors Foreman Anti-corrosion coating of embedded parts Thickness, density and adhesion of coating Visually thickness gauge, engraving die Before embedding Foreman, laboratory Installation of balconies Embedding, marking ka, slope of balconiesVisually, folding metal meter , construction level, 2-meter strip After installing balconies Foreman Installation of lintels Position of lintels, support, placement, sealing Visually, folding metal meter After installation Master Installation of stair landings Position of landings, support, placement, sealing Visually, folding metal meter After installation of platforms, lintels Foreman Welding of embedded parts Length, height and quality of welds Visually , tapping with a hammerBefore performing the anti-corrosion coatingMasterSoundproofing deviceDesign, careful executionVisuallyImmediately after completionMaster

Laying walls from brick blocks

SNiP III-V.4-72, table. 8, pp. 3.18, 3.19, 3.21, 3.23

SNiP III-17-78

Permissible deviations of block sizes from the design ones: block thickness – plus 5 mm; along the length and height of the block - from plus 5 to 10 mm; by diagonal difference – 10 mm; in the position of window and door openings – ± 10 mm; when the embedded parts are displaced – ±5 mm.

Permissible deviations during installation: surfaces and angles of masonry from the vertical: per floor – ±10 mm; full height – ±30 mm; according to the marks of edges and floors – ±15 mm; by displacement of structure axes – ±10 mm; rows of masonry from the horizontal to 10 m in length - 15 mm.

In table 1.41 indicates the objects and operations to be controlled during the construction of walls made of brick blocks.

Hidden works include the following: laying walls from brick blocks; correct installation of lighthouse blocks at the floor level; installation of blocks with smoke and ventilation ducts; installation of embedded parts; welding of embedded parts of pipes of sanitary blocks; installation of prefabricated reinforced concrete floor slabs.

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 load-bearing 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 allowed.

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 at a calculated seismicity of 7-8 points should be taken equal to 15%, and at 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

	Distances, m, at calculated seismicity, points

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

Wall element	Wall element size, m, at calculated seismicity, points	Notes

Partitions with a width of at least m, when laying:			The width of the corner walls should be taken 25 cm more than indicated in the table. Partitions of smaller width must be reinforced with reinforced concrete framing or reinforcement


2. Openings with a width of no more than m, for masonry of category I or II			Openings of larger width should be bordered with a reinforced concrete frame
3. Ratio of the width of the wall to the width of the opening, not less
4. Protrusion of walls in plan, no more, m
5. Removal of cornices, no more, m:			Removal of unplastered wooden
from wall material			cornices allowed
from reinforced concrete elements connected with anti-seismic belts
wooden, plastered over metal mesh

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 category V railways and on railway tracks of 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 the 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.

1. For laying load-bearing and self-supporting walls and filling the frame, you must use:

Solid or hollow brick of grade no lower than 75 with holes up to 14 mm in size;

Concrete stones, solid and hollow blocks of grade 50 and higher, including lightweight concrete with a density of at least 1200 kg/m 3 ;

Stones and blocks made of shell rock, limestone grade no less than 35 or tuff grade 50 and higher.

For construction in seismic areas, the use of stones with large voids and thin walls, and masonry with backfill is prohibited.

2. Masonry of walls made of bricks and small blocks should be carried out using complex masonry mortars of a grade not lower than 25 in conditions of positive outside temperatures and not lower than 50 in conditions of negative temperatures, and masonry of large blocks should be carried out using mortars of a grade not lower than 50.

The use of slag Portland cement and pozzolanic Portland cement for the preparation of polymer cement mortars is not allowed.

3. Anti-seismic joints in the masonry must be made by erecting paired walls. The width of the seams is determined by calculation, but it should not be less than:

For building heights up to 5 m - 30 mm;

For higher building heights, the height is increased by 20 mm for every 5 m.

Anti-seismic joints should not have fillings that would prevent mutual movements of building compartments. If necessary, it is allowed to cover anti-seismic seams with aprons or seal them with flexible materials.

4. The dimensions of the wall elements of stone buildings should be determined by calculation, but they should not be less than the values given in the table. 3.

Table 3

(SNiP 3.03.01-87)

Corner partitions are made 25 cm wider than indicated in the table. 3. When constructing openings exceeding

dimensions given in table. 3, they must be surrounded by a reinforced concrete frame.

5. Horizontal masonry joints must be reinforced with mesh in compliance with the requirements given in SNiP-N-7-81* and this section.

For horizontal reinforcement of solid sections of walls and piers made of brick or small blocks, meshes with longitudinal reinforcement with a diameter of 5-6 mm with transverse rods with a diameter of 3-4 mm, located at a distance of no more than 40 cm from each other, should be used. Reinforcement should be carried out at least every 5 rows of bricks or every 40 cm along the height of masonry made of small blocks or stones.

The junction of stone walls is reinforced with meshes with a total cross-sectional area of longitudinal reinforcement of at least 1 cm2, a length of 1.5 m every 700 mm in height with a calculated seismicity of 7-8 points and after 500 mm - with 9 points.

6. All types of masonry must have vertical reinforcement or include vertical reinforced concrete elements made of concrete of class not lower than B12.5, the reinforcement of which is connected to anti-seismic belts in accordance with SNiP II-7-81*.

Reinforced concrete inclusions in masonry must be made open on at least one side in order to ensure control over the quality of their concreting. They are connected to the masonry using reinforcing mesh (3-4 Ø 0 6 mm A-1), running them into the masonry 70 cm and positioned at the same spacing as the joint reinforcement.

Reinforced concrete inclusions (cores) are connected to the masonry with closed clamps with a diameter of 5-6 mm, which are placed in horizontal joints of the masonry and brought to the depth of the wall:

If the ratio of its height to width is more than 1 - over the entire width in increments of at least 40 cm for 9-point calculated seismicity, up to 65 cm for 7-8-point seismicity;

When the ratio is less than 1 - at a distance of at least 50 cm with a similar step at the corresponding calculated seismicity.

7. Reinforced concrete anti-seismic belts in the level of floors and coverings along all longitudinal and transverse walls are made with a wall thickness of up to 50 cm equal to their thickness, and with a thickness of more than 50 cm it is allowed to install belts 10-15 cm wide less than the thickness of the walls.

8. The height of reinforced concrete belts must be at least 15 cm. The cross-section of their longitudinal reinforcement is determined by calculation.

9. Lintels in the walls must be installed to their full thickness and embedded in the masonry to a depth of at least 350 mm on both sides. With an opening width of up to 1.5 m, sealing of lintels is allowed at 250 mm.

Masonry of walls made of small-piece stone materials must be carried out in compliance with the following requirements:

Masonry should be done using single-row (chain) dressing;

All masonry joints should be filled completely with mortar, with the mortar trimmed on the outer sides of the masonry;

Temporary (installation) 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.

10. Monitoring the strength of normal adhesion of the solution should be performed at the age of 7 days. The adhesion value should be 50% of the strength at the age of 28 days. If the strength does not correspond to the design value, it is necessary to stop the work until the issue is resolved by the design organization.

BUILDINGS WITH LOAD-LOADING WALLS MADE OF BRICK OR MASONRY - SNiP II-7-81 CONSTRUCTION IN SEISMIC AREAS