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Expansion seam: types and device. Expansion joints in buildings Purpose of expansion joints and their design solution

Expansion seam

Expansion seam- designed to reduce loads on structural elements in places of possible deformations that occur when air temperature fluctuates, seismic phenomena, uneven soil settlement and other influences that can cause dangerous self-loads that reduce the load-bearing capacity of structures. It is a kind of cut in the structure of a building, dividing the structure into separate blocks and, thereby, giving the structure a certain degree of elasticity. For sealing purposes, it is filled with elastic insulating material.

Depending on the purpose, the following expansion joints are used: temperature, sedimentary, anti-seismic and shrinkage.

Expansion joints divide the building into compartments from ground level to the roof inclusive, without affecting the foundation, which, being below ground level, experiences temperature fluctuations to a lesser extent and, therefore, is not subject to significant deformations. The distance between expansion joints is taken depending on the wall material and design winter temperature construction area.

Individual parts of the building may have different heights. In this case, the foundation soils located directly under different parts of the building will bear different loads. Uneven soil deformation can lead to cracks in walls and other building structures. Another reason for uneven settlement of the foundation soils may be differences in the composition and structure of the foundation within the building area. Then, in buildings of considerable length, even with the same number of storeys, sedimentary cracks may appear. To avoid the occurrence of dangerous deformations in buildings, they arrange sedimentary joints. These seams, unlike temperature seams, cut buildings along their entire height, including foundations.

If it is necessary to use expansion joints in one building different types, if possible, they are combined in the form of so-called temperature-sedimentation joints.

Anti-seismic joints are used in buildings constructed in areas prone to earthquakes. They cut the building into compartments, which from a structural point of view should represent independent stable volumes. Along the lines of anti-seismic seams, double walls or double rows of load-bearing racks are placed, which are part of the load-bearing frame system of the corresponding compartment.

Shrinkage joints are made in walls built from monolithic concrete various types. Monolithic walls decrease in volume as concrete hardens. Shrinkage joints prevent the occurrence of cracks that reduce the load-bearing capacity of the walls. During hardening monolithic walls the width of the shrinkage joints increases; Once the shrinkage of the walls is complete, the seams are tightly sealed.

For organization and waterproofing expansion joints use different materials:
- sealants
- putty
- waterstops

Links

• Expansion joints of buildings
• Bridge expansion joints

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LECTURE No. 8

EXTERIOR WALLS OF LOW-RISE BUILDINGS AND THEIR ELEMENTS

Lecture plan.

General requirements.

Expansion joints.

Wall classification

Structural elements of walls.

General requirements and classification

One of the most important and complex structural elements of a building is outer wall (4.1).

External walls are subject to numerous and varied force and non-force impacts (Fig. 4.1). They perceive their own weight, permanent and temporary loads from floors and roofs, exposure to wind, uneven deformations of the base, seismic forces, etc. From the outside, external walls are exposed to solar radiation, precipitation, variable temperatures and humidity of the outside air, external noise, and from the inside - exposure to heat flow, water vapor flow, noise.

Fig.4.1. Loads and impacts on the external wall structure.

Performing the functions of an external enclosing structure and a composite element of facades, and often a load-bearing structure, the external wall must meet the requirements of strength, durability and fire resistance corresponding to the capital class of the building, protect the premises from adverse external influences, ensure the necessary temperature and humidity conditions of the enclosed premises, and have decorative qualities. At the same time the design outer wall must meet industrial requirements, as well as economic requirements for minimum material consumption and cost, since external walls are the most expensive structure (20 - 25% of the cost of all building structures).

In the external walls there are usually window openings for lighting the premises and doorways for entrance and exit to balconies and loggias. The complex of wall structures includes filling of window openings, entrance and balcony doors, open space structures. These elements and their connections to the wall must meet the requirements listed above. Since the static functions of walls and their insulating properties are achieved through interaction with internal load-bearing structures, the development of external wall structures includes the solution of interfaces and joints with floors, internal walls or frames.

Expansion joints

External walls, and with them the rest of the building structures, if necessary and depending on the natural-climatic and engineering-geological conditions of construction, as well as taking into account the features of space-planning solutions, are cut vertically expansion joints(4.2) of various types: temperature-shrinkage, sedimentary, anti-seismic, etc. (Fig. 4.2).

Fig.4.2. Expansion joints: a – temperature-shrinkable; b – sedimentary type I; c – sedimentary type II; d – antiseismic.

Temperature shrinkage seams arranged to avoid the formation of cracks and distortions in the walls caused by the concentration of forces from the effects of variable temperatures and shrinkage of the material (masonry, monolithic or prefabricated concrete structures, etc.). Temperature-shrinkage joints cut through the structures of only the ground part of the building. The distances between temperature-shrinkage joints are determined in accordance with climatic conditions and physical and mechanical properties of wall materials. So, for example, for external walls made of clay brick on mortar grade M50 or more, the distance between temperature-shrinkage joints of 40 - 100 m is taken according to SNiP II-22-81 “Stone and reinforced masonry structures”. In this case, the shortest distance refers to the most severe climatic conditions.

In buildings with longitudinal load-bearing walls seams are arranged in the area adjacent to transverse walls or partitions; in buildings with transverse load-bearing walls, seams are often arranged in the form of two paired walls. The smallest seam width is 20 mm. Seams must be protected from blowing, freezing and through leaks using metal expansion joints, sealing, and insulating liners. Examples of design solutions for temperature-shrinkage joints in brick and panel walls are given in Fig. 4.3.

Fig.4.3. Device details expansion joints in brick and panel buildings: a – with longitudinal load-bearing walls (in the area of ​​the transverse stiffness diaphragm); b – with transverse walls in pairs interior walls; c – in panel buildings with transverse walls; 1 – outer wall; 2 – internal wall; 3 – insulating liner wrapped in roofing felt; 4 – caulk; 5 – solution; 6 – cover plate; 7 – floor slab; 8 – outer wall panel; 9 – the same, internal.

Sedimentary seams should be provided in places where there are sharp changes in the number of storeys of the building (sedimentary joints of the first type), as well as in case of significant uneven deformations of the base along the length of the building, caused by the specific geological structure of the base (sedimentary joints of the second type). Settlement seams of the first type are prescribed to compensate for differences in vertical deformations of ground structures of the high and low parts of the building, and therefore they are arranged similarly to temperature-shrinkable ones only in ground structures. The design of the seam in frameless buildings provides for the installation of a sliding seam in the zone of support of the floor of the low-rise part of the building on the walls of the multi-story, in frame buildings - hinged support of the crossbars of the low-rise part on the columns of the high-rise. Sedimentary joints of the second type cut the building to its entire height - from the ridge to the base of the foundation. Such joints in frameless buildings are constructed in the form of paired frames. The nominal width of settlement joints of the first and second types is 20 mm.

The need for such seams is determined external conditions and geometric design parameters.

With any chosen dressing system, the construction of the wall begins with laying the corners. It is important to arrange the dressing of seams in the corners not only in such a way that the selected dressing pattern in the outer versts of both intersecting walls is observed, but also in such a way that the dressing is performed with maximum overlap of the seams.

According to their purpose, expansion joints can be temperature or sedimentary. The location of expansion joints must be indicated in the project.

Sedimentary seams

Settlement seams are installed to prevent uneven settlement of the structure along its length. These seams divide the building or structure into compartments along the entire height of the structures: from the base of the foundation to the cornice. A foundation divided into compartments by a sedimentary seam is called a split foundation. The structure of the sedimentary joint in the masonry of the foundation and wall looks different.

The seam must be perpendicular to the wall or foundation. At the seam, the bricks are not tied together; instead, they are arranged hydro insulating material in two or three layers. The seam in the foundation is made straight, in the wall - with a tongue (a protrusion on one side of the seam and a depression on the other side). The thickness of the tongue and groove is usually half a brick, less often - a quarter of a brick. Above the edge of the foundation, under the tongue, a gap is made 1-2 bricks (rows) high to prevent pressure from the tongue on the foundation masonry in case of uneven settlement. All joints between the foundation masonry and the wall masonry must be sealed to protect the wall from moisture penetration from the foundation.

If the foundation is made of a different material, the principles of constructing a sedimentary seam do not change.

The thickness of the sedimentary seam in brickwork should be 10-20 mm, so the arrangement of joints does not affect the change in the length of the building (it simply replaces part of the vertical joints of the masonry).
WITH outside walls, sedimentary seams are sealed with tarred tow, silicone sealant or a special seal. Moreover, the first option (with tarred tow) is ineffective, so if possible, you should choose another option.

The need to install sedimentary joints arises in several cases.

1. Adjacency new wall to the old one. In this case, the seam can be made without a tongue and groove, since cutting a groove in old wall- a labor-intensive task.
2. The adjoining of one part of the building to another: for example, when a veranda or porch is adjacent to the main part of the building, and the foundation for the extension can be built with less consumption of materials (smaller cross-section). In this case, the settlement of the porch and the main part of the building will be different, and in the absence of a settlement seam, cracks and other deformations of the masonry may occur.
3. Construction on soils with uneven settlement. This property of the soil base can be judged by the buildings existing on the site, the surface of the earth without cultivation (you can see a pronounced settlement of the soil from it), or geological surveys. If it is not possible to determine the condition of the soil using the last option, they resort to the first two. It is important to remember that cracks in buildings can be caused not only by uneven settlement of the soil foundation, but also by errors made in the design (incorrect calculation of the foundation, lack of settlement joints in a long wall, etc.). However, if buildings nearby have cracks, it is better to provide settlement joints in it in any case when constructing a new structure.

Expansion joints

Temperature (temperature-shrinkage) joints protect a building or structure from deformations (cracks, ruptures of masonry, distortions, shifts of masonry at seams) associated with changes in air temperature and the structures themselves. At low temperatures masonry tends to shrink and expand in hot weather. So, for every 10 m of length brick construction when the temperature changes from 20 °C to -20 °C, it shrinks in size by 5 mm. In addition, temperature differences can occur in different parts of the building.

Expansion joints divide the building into compartments along the entire height of the walls, not including the foundation. That is, unlike sedimentary joints, the foundation is not separated by expansion joints. The construction of an expansion joint in a brick wall is similar to the construction of a sedimentary joint: in the form of a tongue and groove with a layer of insulating material and sealing with sealant on the outside of the wall. The sealant for sealing expansion joints must be designed for all temperatures possible during the operation of the building or structure.

The thickness of the expansion joint in the brickwork should be 10-20 mm. If the laying is carried out at an air temperature of 10 ° C or higher, the thickness of the seam can be reduced.

The need to install expansion joints arises when brick walls are long and when there are significant differences in air temperature between winter and summer periods year. Building codes and the rules establish the maximum permissible distances between expansion joints in brick walls. In the most difficult climatic conditions the maximum distance between expansion joints in heated buildings in masonry made of ceramic bricks is 50 m, in masonry from sand-lime brick- 35 m. Since the walls of individual buildings rarely reach such a length, expansion joints in them are practically not suitable. For unheated closed buildings maximum length walls without expansion joints can be: in masonry made of ceramic bricks - 35 m, in masonry made of sand-lime bricks - 24.5 m. For unheated open buildings (for example, brick fences) these standard values ​​are respectively 30 m and 21 m.

If it is necessary to install both settlement and temperature-shrinkage joints in a building, they are combined and a universal-purpose expansion joint (or several joints) is installed, with cutting of structures along the entire height.

|| Concrete work || Solutions || Rubble masonry || Materials, tools, devices used for stone and brickwork || General information about masonry. Types of masonry and purpose || Transportation, storage, supply and placement of bricks || Cutting systems || Face masonry and wall cladding. Types of facade finishing || Scaffolding and scaffolding || Solid brickwork || Settlement and expansion joints || Masonry and installation work in winter. Carrying out work at negative temperatures || Repair, restoration, stone work. Masonry Repair Tools

The settlement joint divides the building lengthwise into parts if the foundations under the building have an uneven settlement. Vertical settlement joints run along the entire height and width of the building from the cornice to the base of the foundation, and the places where the building is divided by the settlement joint are indicated in the design.

Rice. 104. :
a - section; b - wall plan; c - foundation plan; 1 - foundation; 2 - wall; 3 - wall seam; 4 - tongue and groove; 5 - clearance for upset; 6 - foundation seam

Sedimentary joints in the walls (Fig. 104) are made in the form of tongue-and-groove joints, half a brick thick, with two layers of roofing felt laid, in foundations without tongue-and-groove. To prevent the tongue and groove from resting against the foundation masonry during settlement, an empty space of one or two bricks is left above the upper edge of the foundation under the tongue of the wall, otherwise the masonry may collapse in this place. Sedimentary seams are caulked with tarred tow. So that precipitation and groundwater did not get through the sedimentary seam into the basement, do clay castle. The expansion joint protects the building from cracks due to temperature changes. So, stone buildings at a temperature of 20°C they have a length, for example, 20 m, and at -20°C they are shortened by 1 cm. Expansion joints, like sedimentary ones in the form of tongue and groove, are made only within the height of the building wall. For brickwork, the width of the settlement and expansion joints is 10-20 mm or less if the outside air temperature during the laying period is 10°C or higher.

The laying of projections (pilasters) of the walls is carried out using a chain (single-row) or multi-row ligation system, if the width of the pilaster is 4 or more bricks, if the width of the pilaster is three and a half bricks using a three-row ligation system, as when laying pillars. To connect the protrusion with the main masonry, depending on the size of the pilaster, partial or whole bricks are used. The techniques for laying out bricks are the same as for tying wall intersections. Laying walls with niches is carried out in case of installation heating devices etc. Niches are made using the same dressing systems as for solid areas. Niches form, interrupting in the required places, an internal mile, and in places of corners, incomplete interlocking bricks are placed to connect them with the wall (Fig. 105).

Rice. 105.

The laying of walls with channels is carried out when laying gas ducts, ventilation ducts, etc. The channels are placed in the internal walls of the building, the thickness of which is 38 cm - in one row, and in walls 64 cm thick - in two rows. Channels usually have dimensions of 140x140 mm (1/2x1/2 bricks), chimneys large ovens and slabs - 270x140 mm (1 1/2x1/2 bricks) or 270x270 mm (1x1 brick). Ventilation channels and flue ducts in walls made of brick, slag concrete and hollow bricks are laid out from ordinary clay bricks with the masonry of the channel interconnected with the masonry of the wall (Fig. 106). The thickness of the walls of the channels should be half a brick and the partitions between them should be half a brick. Channels run vertically in the wall; sometimes channel bends are allowed no more than 1 m and the angle to the horizon is 60°. In the area where the channel deviates from the vertical, the cross-section remains the same as that of the vertical channel. The inclined sections are made of hewn bricks, the rest of the masonry of the vertical section is made of whole bricks (Fig. 107).

Rice. 106.
a - one and a half bricks; b - c 2 bricks

Rice. 107.

The solutions used for laying smoke and ventilation ducts are the same as for laying the main walls of the building. Chimneys in low-rise buildings are laid out on clay-sand mortar; the fat content of the clay plays a major role in the composition of the mortar. Wooden parts where they pass chimneys, the chimney is cut (Fig. 107, b) from fireproof materials (brick, asbestos) and the thickness of the channel walls is increased. Ventilation ducts passing next to the smoke stations are cut in the same way as wooden channels. Cuttings between structures - floor beams, mauerlats - and smoke, i.e. inner surface the flue is 38 cm if the structure is not protected from fire, and 25 cm if there is protection.

The locations of the channels are preliminarily marked on the section of the wall being laid out according to a template - a board with cutouts, with the dimensions and required markings of the channels. The same template is used to check the correctness during the laying process. To prevent the size of the channels from decreasing, buoys in the form of hollow boxes made of boards are inserted into them. Their cross-section corresponds to the dimensions of the channels, their height is at the level of ten rows of masonry. The buoys ensure the accuracy of the channel shape, do not allow the channels to become clogged, and the masonry joints are better filled with mortar. The buoys are rearranged during the laying process after 6-7 rows of masonry. The filling of channel masonry joints must be of high quality, otherwise soot will settle. Therefore, after rearranging the buoys, the seams are rubbed down. To avoid sagging of the solution, smooth the seams with a mop, having previously moistened it with water. Check the channels using a ball with a diameter of 100 mm. A ball tied on a cord is lowered into the channel, and as it is lowered, the location of the blockage is determined. The laying of walls when filling the frames is carried out using bandaging of seams, as with conventional wall laying. According to the project, additional fastenings of the masonry to the frame are arranged. Reinforcing bars are placed into the masonry seams to secure the frame to the embedded parts.

Deformation is a change in the shape or size of a material body (or part of it) under the influence of any physical factors (external forces, heating and cooling, changes in humidity from other influences). Some types of deformations are named in accordance with the names of the factors affecting the body: temperature, shrinkage (shrinkage is a reduction in the size of a material body when its material loses moisture); sedimentary (settlement is the subsidence of the foundation when the soil underneath is compacted), etc. If by a material body we mean individual structures or even structural system in general, such deformations under certain conditions can cause violations of their bearing capacity or loss of their performance qualities.

Long buildings are subject to deformation under the influence of many reasons, for example: with a large difference in the load on the foundation under the central part of the building and its side parts, with heterogeneous soil at the base and uneven settlement of the building, with significant temperature fluctuations in the outside air and other reasons. In these cases, cracks may appear in the walls and other elements of buildings, which reduce the strength and stability of the building. To prevent the appearance of cracks in buildings, expansion joints , which cut buildings into separate compartments.

Settlement seams are made in places where uneven settlement can be expected different parts buildings: on the boundaries of areas with different loads on the foundation, which is usually a consequence of the difference in height of buildings (with a difference in heights of more than 10 m, the installation of sedimentary joints is mandatory), on the boundaries of areas with different construction sequences, as well as in places where new walls adjoin existing ones, on boundaries of areas located on dissimilar foundations, in all other cases when uneven settlement of adjacent areas of the building can be expected.

The design of the sedimentary joint must provide freedom of vertical movement of one part of the building relative to another. Therefore, sedimentary joints, unlike temperature joints, are installed not only in the walls, but also in the foundation of the building, as well as in the ceilings and roof. Thus, sedimentary seams cut right through the building, dividing it into separate parts.

Depending on the purpose The following expansion joints are distinguished: shrinkage, temperature, sedimentary and anti-seismic.

Shrink seams. In monolithic concrete or reinforced concrete walls, when concrete sets (hardens), its volume decreases, the so-called shrinkage, which entails the appearance of cracks. Therefore, in buildings with such walls, seams are made regardless of air temperature fluctuations, which are called shrinkage.

Expansion joints. With significant changes in outside air temperature, deformations occur in buildings that are long. In summer, when heated, buildings lengthen and expand, and in winter, when cooled, they contract. These deformations are small, but they can lead to cracks. To avoid this, buildings are divided by expansion joints, cutting them across or along the entire height to the foundations. Expansion joints are not installed in foundations, as they... being in the ground, they are not subject to significant changes in air temperature. Expansion joints must ensure horizontal movement of the individual parts of the building that they separate.

The distance between expansion joints varies within a very wide range (from 20 to 200 mm).

Sedimentary seams. In all cases where uneven settlement of adjacent parts of the building, unequal in size and time, can be expected, settlement joints are installed.

Such a settlement could be, for example:

a) at the boundaries of areas with different loads on the foundation due to different standard loads or with different number of storeys of the building (with a height difference of more than 10 m or more than 3 floors);

b) at the boundaries of areas with heterogeneous foundations ( sandy soils give a small and short-term sediment, and clayey ones - a large and long-lasting one);

c) at the boundaries of areas with different order of construction of building compartments (compressed and uncompressed soils);

d) in places where newly erected walls adjoin existing ones;

e) at complex configuration buildings in plan;

f) in some cases under dynamic loads.

The design of the sedimentary joint must ensure freedom of vertical movement of one part of the building relative to another, therefore, sedimentary joints, unlike temperature joints, are installed not only in the walls, but also in the foundation of the building, as well as in the floors and roof. Thus, sedimentary seams cut right through the building, dividing it into separate parts.

If a building requires temperature and sedimentation joints, they are usually combined and are then called temperature-sedimentation joints. Temperature-sedimentation joints must ensure horizontal and vertical movement of parts of buildings. They can be temperature-sedimentary and only sedimentary seams.

Anti-seismic seams. In areas prone to earthquakes, buildings are cut into separate compartments using anti-seismic seams to ensure independent settlement of their individual parts. These compartments must represent independent stable volumes, for which purpose double walls or double rows of load-bearing posts included in the load-bearing frame of the corresponding compartment are located along the lines of anti-seismic seams. These seams are designed in accordance with the instructions of the DBN.

Anti-seismic seams can be combined with temperature seams, if necessary.

Constructive solutions for expansion joints in buildings

a - expansion joint in a one-story frame building; b - sedimentary joint in a one-story frame building

c - expansion joint in buildings with transverse load-bearing large-panel walls; d - expansion joint in a multi-storey frame building; d, f, g, - options for expansion joints in stone walls

1 - column; 2 - load-bearing structure coatings; 3 - covering plate; 4 - foundation for the column; 5 - common foundation for two columns; 6 - wall panel; 7 - insert panel; 8 - carrier wall panel; 9 - floor slab; 10 - thermal insert.

Maximum distance between expansion joints