Constructive solutions for curved external walls. External walls and their elements

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

Fig.4.1. Loads and impacts on the structure of the outer wall.

Performing the functions of an external enclosing structure and a composite element of facades, and often a supporting 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, provide the necessary temperature and humidity conditions of the enclosed premises, have decorative qualities. At the same time, the design of the outer wall must meet the industrial requirements, as well as the economic requirements of minimum material consumption and cost, since the outer walls are the most expensive structure (20 - 25% of the cost of all building structures).

In the outer walls, there are usually window openings for lighting the premises and doorways - entrances and exits to balconies and loggias. The complex of wall structures includes the filling of window openings, entrance and balcony doors, the construction of open spaces. These elements and their interfaces with the wall must meet the requirements listed above. Since the static functions of the walls and their insulating properties are achieved by interacting with internal load-bearing structures, the development of external wall structures includes the solution of interfaces and joints with floors, internal walls or framing.

expansion joints

The outer 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-shrinkage; b – sedimentary type I; c – sedimentary type II; d - anti-seismic.

Thermal shrinkage seams arrange in order to avoid the formation of cracks and distortions in the walls caused by the concentration of efforts from exposure to 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 the temperature-shrinkage joints are assigned in accordance with climatic conditions and the physical and mechanical properties of wall materials. So, for example, for external walls made of clay bricks on a mortar grade M50 and more, the distance between the temperature-shrinkage joints of 40–100 m is taken according to SNiP II-22-81 “Stone and reinforced masonry structures”. In this case, the smallest distance refers to the most severe climatic conditions.

In buildings with longitudinal load-bearing walls, seams are arranged in the area of adjacency 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 joint width is 20 mm. The seams must be protected from blowing, freezing and through leaks with the help of metal compensators, sealing, and insulating liners. Examples of constructive solutions for temperature-shrinkage joints in brick and panel walls are given in Fig. 4.3.

Fig.4.3. Details of the device of expansion joints in brick and panel buildings: a - with longitudinal load-bearing walls (in the area of the transverse stiffening diaphragm); b - with transverse walls with paired internal walls; c - in panel buildings with transverse walls; 1 - outer wall; 2 - inner wall; 3 - insulating insert in a wrapper made of roofing felt; 4 - caulk; 5 - solution; 6 - flashing; 7 - floor slab; 8 - outer wall panel; 9 - the same, internal.

Sedimentary seams should be provided in places of sharp differences in the number of storeys of the building (sedimentary seams of the first type), as well as in case of significant uneven deformation of the base along the length of the building, caused by the specifics of the geological structure of the base (sedimentary seams of the second type). Sedimentary joints of the first type are appointed 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-shrinkage joints 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 high-rise part, in frame buildings - the hinged support of the crossbars of the low-rise part on the columns of the high-rise part. Sedimentary seams of the second type cut the building to its entire height - from the ridge to the base of the foundation. Such seams in frameless buildings are designed in the form of paired frames. The nominal width of the sedimentary joints of the first and second types is 20 mm.

Wall classification

External wall structures are classified according to the following criteria:

The static function of the wall, determined by its role in the structural system of the building;

Material and construction technology, determined by the construction system of the building;

Structural solution - in the form of a single-layer or layered enclosing structure.

According to the static function, they distinguish (Fig. 4.4) bearing walls (4.3), self-supporting walls(4.4) and curtain walls (4.5).

Fig.4.4. Classification of external walls by bearing capacity: a - bearing; b - self-supporting; c - non-bearing

Non-load-bearing walls are floor-by-floor supported on adjacent internal structures of the building (ceilings, walls, frame).

Bearing and self-supporting walls perceive, along with vertical and horizontal loads, being vertical elements of the rigidity of structures. In buildings with non-load-bearing external walls, the functions of vertical stiffeners are performed by the frame, internal walls, diaphragms or stiffeners.

Bearing and non-bearing external walls can be used in buildings of any number of storeys. The height of self-supporting walls is limited in order to prevent operationally unfavorable mutual displacements of self-supporting and internal load-bearing structures, accompanied by local damage to the finish of the premises and the appearance of cracks. In panel houses, for example, it is permissible to use self-supporting walls with a building height of no more than 4 floors. The stability of self-supporting walls is provided by flexible connections with internal structures.

Load-bearing external walls are used in buildings of various heights. The limiting number of storeys of a load-bearing wall depends on the bearing capacity and deformability of its material, construction, the nature of the relationship with internal structures, as well as on economic considerations. So, for example, the use of lightweight concrete panel walls is advisable in houses up to 9-12 floors high, load-bearing brick exterior walls - in mid-rise buildings, and walls of a steel lattice shell structure - in 70 - 100-story buildings.

According to the material, four main types of wall structures are distinguished: concrete, stone, non-concrete materials and wood. In accordance with the building system, each type of wall contains several types of structures: concrete walls - from monolithic concrete, large blocks or panels; stone walls - brick or from small blocks, walls from stone large blocks and panels; wooden walls - chopped, frame-panel, panel and panel.

Exterior walls can be single-layer or layered construction. Single-layer walls are built from panels, concrete or stone blocks, cast-in-place concrete, stone, brick, wooden logs or beams. In layered walls, the performance of different functions is assigned to different materials. Strength functions provide concrete, stone, wood; durability functions - concrete, stone, wood or sheet material (aluminum alloys, enameled steel, asbestos cement, etc.); thermal insulation functions - effective heaters (mineral wool boards, fibrolite, expanded polystyrene, etc.); vapor barrier functions - rolled materials (lining roofing material, foil, etc.), dense concrete or mastics; decorative functions - various facing materials. An air gap can be included in the number of layers of such a building envelope. Closed - to increase its resistance to heat transfer, ventilated - to protect the room from radiation overheating or to reduce deformations of the outer facing layer of the wall.

Question 4.1. Can walls be called load-bearing if they take the load not only from their own weight, but also from other elements of the building?

4.1. answer: yes

4.1. answer: NO

Structural wall solutions

The thickness of the outer walls is chosen according to the largest of the values obtained as a result of static and heat engineering calculations, and is assigned in accordance with the design and heat engineering features of the enclosing structure.

In prefabricated concrete housing construction, the calculated thickness of the outer wall is linked to the nearest larger value from the unified series of outer wall thicknesses adopted in the centralized manufacture of molding equipment 250, 300, 350, 400 mm for panel and 300, 400, 500 mm for large-block buildings.

The calculated thickness of the stone walls is coordinated with the dimensions of the brick or stone and is taken equal to the nearest greater structural thickness obtained during masonry. With brick dimensions of 250 × 120 × 65 or 250 × 120 × 88 mm (modular brick), the thickness of the walls of solid masonry is 1; 1.5; 2; 2.5 and 3 bricks (taking into account vertical joints of 10 mm between individual stones) is 250, 380, 510, 640, and 770 mm.

The structural thickness of a wall made of sawn stone or lightly concrete small blocks, the unified dimensions of which are 390 × 190 × 188 mm, when laid in one stone is 390 and in 1.5 - 490 mm.

The construction of walls is based on the comprehensive use of the properties of the materials used and solves the problem of creating the required level of strength, stability, durability, insulating and architectural and decorative qualities.

In accordance with modern requirements for the economical use of materials, when designing low-rise residential buildings with stone walls, they try to use the maximum amount of local building materials. For example, in areas remote from highways, small locally produced stones or monolithic concrete are used to build walls in combination with local heaters and on local aggregates, which require only imported cement. In settlements located near industrial centers, houses are designed with walls made of large blocks or panels manufactured at the enterprises of this region. At present, stone materials are being increasingly used in the construction of houses in garden plots.

When designing low-rise buildings, two schemes for the constructive solution of external walls are usually used - solid walls made of homogeneous material and lightweight multilayer walls made of materials of different densities. For the construction of internal walls, only solid masonry is used. When designing external walls according to the solid masonry scheme, preference is given to less dense materials. This technique allows you to achieve the minimum thickness of the walls in terms of thermal conductivity and more fully use the load-bearing capacity of the material. It is advantageous to use building materials of high density in combination with materials of low density (lightweight walls). The principle of lightweight walls is based on the fact that the bearing functions are performed by a layer (layers) of high-density materials (γ> 1600 kg / m 3), and a low-density material serves as a heat insulator. For example, instead of a solid outer wall made of clay bricks 64 cm thick, you can use a lightweight wall structure made of a layer of the same brick 24 cm thick, with a fiberboard insulation 10 cm thick. Such a replacement leads to a decrease in wall weight by 2.3 times.

For the manufacture of walls of low-rise buildings, artificial and natural small stones are used. At present, artificial firing stones are used in construction (clay brick, solid, hollow, porous and ceramic blocks); non-fired stones (silicate brick, hollow blocks of heavy concrete and solid blocks of lightweight concrete); natural small stones - torn rubble, sawn stones (tuff, pumice, limestone, sandstone, shell rock, etc.).

The size and weight of the stones are designed in accordance with the manual laying technology and taking into account the maximum mechanization of work. The walls are laid out of stones with filling the gap between them with mortar. Most often, cement-sand mortars are used. For laying internal walls, ordinary sand is used, and for external walls, sand of low density (perlite, etc.). Wall laying is carried out with obligatory observance suture dressing(4.6) in series.

As already noted, the width of the masonry wall is always a multiple of the number of halves of the brick. Rows facing the front surface of the masonry are called front verst, and facing the inside - inner verst. The rows of masonry between the inner and front mile are called backfill. Bricks laid long side along the wall form spoon row, and laid across the walls - bonder row. masonry system(4.7) is formed by a certain arrangement of stones in the wall.

The row of masonry is determined by the number of spoon and bond rows. With a uniform alternation of spoon and bond rows, a two-row (chain) masonry system is obtained (Fig. 4.5b). A less labor-intensive multi-row masonry system, in which one row of bricks binds five spoon rows (Fig. 4.5a). In the walls of small blocks erected according to a multi-row system, one row of bonders binds two rows of spoon masonry (Fig. 4.5c).

Fig.4.5. Types of manual laying of walls: a) - multi-row brickwork; b) - chain brickwork; c) - multi-row masonry; d) - chain masonry

Solid masonry of high density stones is used only for the construction of internal walls and pillars and external walls of unheated premises (Fig. 4.6a-g). In some cases, this masonry is used for the construction of external walls in a multi-row system (Fig. 4.6a-c, e). The two-row stone laying system is used only when necessary. For example, in ceramic stones, it is recommended to place void gaps across the heat flow in order to reduce the thermal conductivity of the wall. This is achieved with a chain laying system.

Lightweight external walls are designed in two types - with insulation between two walls of solid masonry or with an air gap (Fig. 4.6i-m) and with insulation lining the solid masonry wall (Fig. 4.6n, o). In the first case, there are three main structural options for walls - walls with horizontal outlets of anchor stones, walls with vertical stone diaphragms (well masonry) and walls with horizontal diaphragms. The first option is used only in cases where lightweight concrete is used as a heater, which monolithizes anchor stones. The second option is acceptable for insulation in the form of pouring lightweight concrete and laying thermal liners (Fig. 4.6k). The third option is used for insulation from bulk materials (Fig. 4.6l) or from lightly concrete stones. Solid masonry walls with an air gap (Fig. 4.6m) also belongs to the category of lightweight walls, since the closed air gap acts as a layer of insulation. It is advisable to take the thickness of the interlayers equal to 2 cm. An increase in the interlayer practically does not increase its thermal resistance, and a decrease sharply reduces the effectiveness of such thermal insulation. More often, the air gap is used in combination with insulation boards (Fig. 4.6k, o).

Fig. 4.6, Variants of manual laying of the walls of low-rise residential buildings: a), b) - solid outer walls made of bricks; c) - a solid internal brick wall; e), g) - solid outer walls made of stones; d), f) - solid internal walls made of stones; i)-m) - lightweight walls with internal insulation; n), o) - lightweight walls with external insulation; 1 - brick; 2 - plaster or cladding with sheets; 3 - artificial stone; 4 - slab insulation; 5 - air gap; 6 - vapor barrier; 7 - wooden antiseptic rail; 8 - backfill; 9 - solution diaphragm; 10 - lightweight concrete; 11 - natural frost-resistant stone

To insulate stone walls from the side of the street, a rigid slab insulation made of lightweight concrete, foam glass, fiberboard is used in combination with a weather-resistant and durable cladding (asbestos cement sheets, boards, etc.). The option of wall insulation from the outside is effective only if there is no access of cold air to the zone of contact between the carrier layer and the insulation layer. To insulate the outer walls from the side of the room, a semi-rigid slab insulation (reed, straw, mineral wool, etc.) is used, located close to the surface of the first or with the formation of an air gap, 16–25 mm thick - “at a distance”. Slabs "at a distance" are attached to the wall with metal zigzag brackets or nailed to wooden antiseptic slats. The open surface of the insulation layer is covered with sheets of dry plaster. Between them and the insulation layer, a vapor barrier layer of glassine, polyethylene film, metal foil, etc. is necessarily placed.

Study and analyze the above material and answer the proposed question.

Question 4.2. Can rows of bricks laid long side along a wall be called poke rows?

4.2. answer: yes

The structural thickness of a wall made of sawn stone or lightly concrete small blocks, the unified dimensions of which are 390 × 190 × 188 mm, when laid in one stone is 390 and in 1.5 - 490 mm.

Fig.4.5. Types of manual laying of walls: a) - multi-row brickwork; b) - chain brickwork; c) - multi-row masonry; d) - chain masonry

Study and analyze the above material and answer the proposed question.

Question 4.2. Can rows of bricks laid long side along a wall be called poke rows?

4.2. answer: yes

4.1. aboutreply: Yes(file address Block 3)

Your answer is correct, because walls are load-bearing only when they take the load from their own weight and from other structural elements of the building.

Go to question 4.2

.1.answer: yes

4.1. aboutreply: NO(file address Block 3)

Your answer is INCORRECT because YOU did not take into account that walls that do not take the load from other elements of the building are classified as either self-supporting or non-bearing.

Return to reading the text

.1.answer: NO

Structural wall solutions

The structural thickness of a wall made of sawn stone or lightly concrete small blocks, the unified dimensions of which are 390 × 190 × 188 mm, when laid in one stone is 390 and in 1.5 - 490 mm.

Fig.4.5. Types of manual laying of walls: a) - multi-row brickwork; b) - chain brickwork; c) - multi-row masonry; d) - chain masonry

Study and analyze the above material and answer the proposed question.

Walls are the main load-bearing and enclosing structures of a building. They must be strong, rigid and stable, have the required fire resistance and durability, be low heat-conductive, heat-resistant, sufficiently air- and sound-tight, and also economical.
Basically, external influences on buildings are perceived by roofs and walls (Fig. 2.13).

Three parts are distinguished near the wall: the lower one is the plinth, the middle one is the main field, the upper one is the entablature (cornice).

Figure 2.13 External impacts on the building: 1 - permanent and temporary vertical force impacts; 2 - wind; 3 - special force effects (seismic or others); 4- vibrations; 5 - lateral soil pressure; 6- soil pressure (resistance); 7 - ground moisture; 8 - noise; 9 - solar radiation; 10 - precipitation; 11 - the state of the atmosphere (variable temperature and humidity, the presence of chemical impurities)

By the nature of the perception and transfer of loads walls (external and internal) are divided into load-bearing, self-supporting and hinged (with a load-bearing frame) (Fig. 2.14). Bearing walls must provide strength, rigidity and stability of the building from the effects of wind loads, as well as loads falling on ceilings and coatings, transferring the resulting forces through the foundations to the foundation. Self-supporting walls must maintain their strength, rigidity and stability when exposed to wind load, from their own weight and the overlying part of the wall. Curtain walls, designed only to protect the premises from atmospheric influences (cold, noise), are designed using highly efficient heat-insulating materials, light multilayer. They usually transfer the load (wind) within one panel and from its own weight to the elements of the building's supporting frame.

By the nature of the placement in the building distinguish between external walls, i.e. enclosing the building, and internal - separating the premises.

By type of materials used walls can be wooden (log, block, frame-panel, etc.), made of stone materials, concrete, reinforced concrete, as well as multi-layered (using highly effective heat-insulating materials as a heat-insulating layer).

The main parts of the outer walls are plinths, openings, piers, lintels, pilasters, buttresses, gables, cornices and parapets (Fig. 2.14). Plinth - the lower part of the wall adjacent to the foundation. The walls have openings for windows, doors and gates. The sections of the walls between the openings are called piers, above the openings - lintels. Crowning cornice - the upper protruding part of the wall. Parapet - part of the wall enclosing the roof in buildings with internal drainage.

Figure 2.14 Wall structures: a - load-bearing in a frameless building; b - the same in a building with an incomplete frame; in - self-supporting; g - hinged; d - the main parts of the walls; 1- foundation; 2 - wall; 3 - overlap; 4 - crossbar; 5 - column; 6 - foundation beam; 7 - strapping beam; 8 - base; 9 - opening; 10 - cornice; 1 - partition; 12 - jumper

In frame one-story industrial buildings with large openings, considerable height and length of walls, fachwerk is used to ensure their stability, which is a reinforced concrete or steel frame that supports the walls, and also perceives the wind load and transfers it to the main frame of the building.

According to the constructive solution, the walls can be solid, or layered.

Walls are the most expensive structures. The cost of external and internal walls is up to 35% of the cost of the building. Consequently, the effectiveness of the constructive solution of the walls significantly affects the technical and economic indicators of the entire building.

When choosing and designing the structure of the walls of civil buildings, it is necessary:

reduce material consumption, labor intensity, estimated cost and prime cost;
apply the most effective materials and wall products;
reduce the weight of the walls;
make maximum use of the physical and mechanical properties of materials;
use materials with high construction and operational qualities that ensure the durability of the walls.

In terms of thermal engineering, the enclosing parts of buildings must meet the following requirements:

provide the necessary resistance to the passage of heat through them;
not have a temperature on the inner surface that differs significantly from the air temperature of the premises so that there is no feeling of cold near the fences, and condensation does not form on the surface;
possessing sufficient heat resistance (thermal inertia) so that fluctuations in the external and internal temperatures are less reflected in fluctuations in the temperature of the internal surface.
maintain a normal humidity regime, because moisture reduces the heat-shielding properties of the fence.

brick walls. Bricks are used as materials for masonry: ordinary clay, silicate, hollow plastic pressing; hollow brick of semi-dry pressing. So, in the conditions of Almaty, the wall thickness is 510 mm (2 bricks), and for internal load-bearing walls - 380 mm (one and a half bricks) and even 250 mm. Ceramic hollow stones and small concrete blocks (eg 490x340x388) can be used. Brick grades 50 - 150.

Common clay brick is made in dimensions 250x120x65 mm (88 mm) and has a bulk density of 1700 - 1900 kg/m 3 .
Effective clay bricks are produced hollow and lightweight. The bulk density of hollow bricks is 1300 - 1450 kg/m 3 , lightweight 700 - 1000 kg/m 3 and more.

silicate brick has a bulk density of 1800 - 2000 kg/m 3 ; dimensions 250x120x65 (88 mm).

Slag brick has a bulk density of 1200 -1400 kg/m 3 .
Hollow ceramic stones differ from hollow bricks in terms of height (138, 188, 298 mm), shape and location of voids. Ceramic stones of plastic pressing with 7 and 18 voids and have dimensions 250x120x138 mm, bulk density 1400 kg/m 3

Lightweight concrete stones there are solid and hollow ones with a bulk density of 1100 - 1600 kg / m 3.

The sizes of stones with slit-like non-through voids are 190x390x188 and 90x390x188, three-hollow - 120x250x138 mm.

The best thermotechnical indicators have stones with slit-like voids.

Facing bricks and stones are divided into profile and ordinary (solid and hollow).

Shaped ceramic slabs are embedded and leaning.

In addition to ceramic products, concrete and other non-fired slabs and stones can be used for wall cladding. Natural stones and slabs from: natural stone is used for laying foundations and walls, for cladding (in the form of facing slabs - sawn, chipped, hewn, polished). Floors, window sills and stair steps are also made from natural stone. Solid masonry made of ordinary bricks and heavy stone materials is used to a limited extent - where increased strength is needed, as well as in rooms with high humidity. In other cases, it is recommended; use lightweight masonry.
Masonry is carried out on heavy (sandy) or light (slag) solutions of grades 10; 25 - 50 and 100.

Continuous masonry is carried out according to a multi-row (spoon) or single-row (chain) system of dressing seams, the laying of narrow piers (with a width of not more than 1.0 m), as well as the laying of brick pillars, is carried out according to a three-row system. The thickness of the horizontal joints is taken equal to 12 mm, vertical 10 mm. To facilitate and insulate, wells filled with lightweight concrete are left in the wall.

Figure 2.15 Walls made of bricks and ceramic stones: a - single-row; b- multi-row; c - L.I. Onishchik; g - brick-concrete; d- well; e - with an air gap; g - with slab insulation; 1- poke; 2 spoons; 3-lightweight concrete; 4-air gap; 5-plaster; 6-plate insulation; 7 grout.

Large block walls. Buildings from large blocks are built without frames and with frames (Fig. 2.16.). By purpose, large blocks are divided into blocks for external and internal walls, for basement walls and plinths, and special blocks (cornice, for bathrooms, etc.). The material for large blocks is lightweight concrete of a class not lower than B5 (slag concrete, expanded clay concrete, cellular concrete, large-pore concrete, concrete on porous gravel) with a bulk weight of 1000; 1400 and 1600 kg / m 3.
Concrete blocks for exterior walls are 300 thick; 400 and 500 mm, for internal walls 300 mm. The outer surface of the blocks is textured with decorative concrete or facing tiles, and the inner surface is prepared for finishing.

Large panel walls. According to the constructive solution, the panels are divided into single-layer and multi-layer (Fig. 2.17). Single-layer panels are made of lightweight concrete with a bulk weight of up to 1200 kg/m 3 , having the required frost resistance and heat-shielding qualities.

Multilayer panels (two-layer and three-layer) consist of a carrier shell that takes all loads and insulation. The outer surface of the panels can be textured with a 20 mm thick decorative layer on white and colored cement, lined with ceramic tiles, etc. The inner surface of the panels must have a 10 mm thick finishing layer.

The transmission of vertical forces in horizontal joints between panels is the most difficult task of large-panel construction.

Figure 2.16. Large-block walls of civil buildings: a - two-, three- and four-row cutting of external load-bearing walls; b-main types of wall blocks; c - two-row cutting of self-supporting walls; I, II, III, IV - rows of blocks; g - layout of blocks in axonometry; blocks: 1 - wall; 2 - jumper; 3 - window sill; 4-belt.

Figure 2.17 Panel walls of civil buildings: Cutting of external walls: a - single-row with panels per room; b- the same for two rooms; c - two-row cutting of the panel structure; g-single-layer concrete; d - two-layer reinforced concrete; e - the same three-layer; g - from rolling plates; 1- panel with an opening; 2- tape panel; 3- wall panel; 4 - reinforcement cage; 5 - lightweight concrete; 6 - decorative concrete; 7 - insulation; 8 - heating panel; 9 - reinforced concrete slab; 10 - rolling plate.

In practice, four main types of compounds have been used (Fig. 2.18.):

platform joint, a feature of which is the support of the ceilings on half the thickness of the transverse wall panels, i.e. step transfer of forces, in which forces are transmitted from panel to panel through the supporting parts of floor slabs;
jagged joint, representing a modification of the platform-type joint, provides deeper support for floor slabs, which, like a dovetail, rest on the entire width of the wall panel, but forces from panel to panel are not transmitted directly, but through the supporting parts of the floor slabs;
contact joint with support of floors on remote consoles and direct transfer of forces from panel to panel;
contact-socket a joint with support of panels also on the principle of direct transfer of forces from panel to panel and support of ceilings through consoles or ribs (“fingers”) protruding from the slabs themselves and stacked in nests specially left in the transverse panels.

Platform joint used for all types of nine-story buildings, as well as experimentally - in 17-story and 25-story buildings with a narrow pitch of transverse load-bearing walls.

Figure 2.18 Types of horizontal joints between load-bearing panels: a-platform; b-toothed; в- contact on remote consoles; d-pin-female

Publication date: January 12, 2007

The article brought to your attention is devoted to the design of the outer walls of modern buildings in terms of their thermal protection and appearance.

Considering modern buildings, i.e. buildings that currently exist should be divided into buildings designed before and after 1994. The starting point in changing the principles of constructive solutions for external walls in domestic buildings is the order of the State Construction Committee of Ukraine No. 247 of 12/27/1993, which established new standards for thermal insulation of enclosing structures of residential and public buildings. Subsequently, by order of the State Construction Committee of Ukraine No. 117 dated June 27, 1996, amendments were introduced to SNiP II -3-79 "Construction Heat Engineering", which established the principles for designing thermal insulation of new and reconstructed residential and public buildings.

After six years of the new norms, there are no longer any questions about their expediency. Years of practice have shown that the right choice was made, which, at the same time, requires careful multilateral analysis and further development.

For buildings designed before 1994 (unfortunately, the construction of buildings according to the old thermal insulation standards is still encountered), the outer walls perform both load-bearing and enclosing functions. Moreover, the load-bearing characteristics were provided with rather insignificant thicknesses of the structures, and the fulfillment of the enclosing functions required significant material costs. Therefore, the reduction in the cost of construction followed the path of a priori low energy efficiency due to well-known reasons for an energy-rich country. This regularity applies equally to buildings with brick walls, as well as to buildings made of large-sized concrete panels. Thermally, the differences between these buildings consisted only in the degree of thermal heterogeneity of the outer walls. Masonry walls can be regarded as thermally quite homogeneous, which is an advantage, since a uniform temperature field of the inner surface of the outer wall is one of the indicators of thermal comfort. However, to ensure thermal comfort, the absolute value of the surface temperature must be sufficiently high. And for the outer walls of buildings created according to the standards before 1994, the maximum temperature of the inner surface of the outer wall at the calculated temperatures of the indoor and outdoor air could be only 12 ° C, which is not enough for thermal comfort conditions.

The appearance of the brickwork walls also left much to be desired. This is due to the fact that domestic technologies for making bricks (both clay and ceramic) were far from perfect, as a result, the brick in the masonry had different hues. Silicate brick buildings looked somewhat better. In recent years, bricks have appeared in our country, made according to all the requirements of modern world technologies. This applies to the Korchevatsky plant, which produces bricks with excellent appearance and relatively good thermal insulation characteristics. From such products it is possible to build buildings, the appearance of which will not be inferior to foreign counterparts. Multi-storey buildings in our country were mainly built from concrete panels. This type of wall is characterized by significant thermal inhomogeneity. In single-layer expanded clay concrete panels, thermal heterogeneity is due to the presence of butt joints (photo 1). Moreover, its degree, in addition to constructive imperfection, is also significantly affected by the so-called human factor - the quality of sealing and insulation of butt joints. And since this quality was low in the conditions of Soviet construction, the joints leaked and froze, presenting the residents with all the “charms” of damp walls. In addition, the widespread non-compliance with the technology of manufacturing expanded clay concrete led to an increased density of the panels and their low thermal insulation.

Things were not much better in buildings with three-layer panels. Since the stiffening ribs of the panels caused the thermal inhomogeneity of the structure, the problem of butt joints remained relevant. The appearance of the concrete walls was extremely unpretentious (photo 2) - we did not have colored concrete, and the paints were not reliable. Understanding these problems, architects tried to give variety to buildings by applying tiles to the outer surface of the walls. From the point of view of the laws of heat and mass transfer and cyclic temperature and humidity influences, such a constructive and architectural solution is absolute nonsense, which is confirmed by the appearance of our houses. When designing
after 1994, the energy efficiency of the structure and its elements became decisive. Therefore, the established principles of designing buildings and their enclosing structures have been revised. The basis for ensuring energy efficiency is strict observance of the functional purpose of each structural element. This applies both to the building as a whole and to the enclosing structures. The so-called frame-monolithic buildings confidently entered the practice of domestic construction, where the strength functions are performed by a monolithic frame, and the outer walls carry only enclosing (heat and sound insulation) functions. At the same time, the constructive principles of buildings with load-bearing outer walls have been preserved and are being successfully developed. The latest solutions are also interesting in that they are fully applicable to the reconstruction of those buildings that were considered at the beginning of the article and which require reconstruction everywhere.

The constructive principle of external walls, which can equally be used for the construction of new buildings and for the reconstruction of existing ones, is continuous insulation and insulation with an air gap. The effectiveness of these design solutions is determined by the optimal selection of the thermophysical characteristics of a multilayer structure - a load-bearing or self-supporting wall, insulation, textured layers, and an outer finishing layer. The material of the main wall can be any and the determining requirements for it are strength and load-bearing.

The thermal insulation characteristics in this wall solution are fully described by the thermal conductivity of the insulation, which is used as PSB-S expanded polystyrene, mineral wool boards, foam concrete, and ceramic materials. Expanded polystyrene is a heat-insulating material with low thermal conductivity, durable and technologically advanced when insulated. Its production has been established at domestic plants (Stirol plants in Irpen, plants in Gorlovka, Zhytomyr, Bucha). The main disadvantage is that the material is combustible and, according to domestic fire standards, has limited use (for low-rise buildings, or in the presence of significant protection from non-combustible lining). When insulating the outer walls of multi-storey buildings, certain strength requirements are also imposed on PSB-S: the density of the material must be at least 40 kg / m3.

Mineral wool boards are a heat-insulating material with low thermal conductivity, durable, technologically insulating, meets the requirements of domestic fire regulations for the outer walls of buildings. In the Ukrainian market, as well as in the markets of many other European countries, mineral wool boards of the ROCKWOOL, PAROC, ISOVER and other concerns are used. A characteristic feature of these companies is a wide range of manufactured products - from soft boards to hard ones. At the same time, each name has a strictly targeted purpose - for roof insulation, inside walls, facade insulation, etc. For example, for facade insulation of walls according to the considered design principles, ROCKWOOL produces FASROCK boards, and PAROC produces L-4 boards. A characteristic feature of these materials is their high dimensional stability, which is especially important for insulation with a ventilated air gap, low thermal conductivity and guaranteed product quality. In terms of thermal conductivity, these mineral wool slabs are no worse than expanded polystyrene (0.039-0.042 WDmK) due to their structure. Targeted production of plates determines the operational reliability of insulation of external walls. It is absolutely not acceptable to use mats or soft mineral wool boards for the considered design options. Unfortunately, in domestic practice there are solutions for wall insulation with a ventilated air gap, when mineral wool mats are used as a heater. The thermal reliability of such products raises serious concerns, and the fact of their rather wide application can only be explained by the lack of a system for commissioning new design solutions in Ukraine. An important element in the construction of walls with facade insulation is the outer protective and decorative layer. It not only determines the architectural perception of the building, but also determines the moisture state of the insulation, being both a protection against atmospheric influences and for continuous insulation an element for removing vaporous moisture that enters the insulation under the influence of heat and mass transfer forces. Therefore, the optimal selection is of particular importance: insulation - a protective and finishing layer.

The choice of protective and finishing layers is determined primarily by economic opportunities. Facade insulation with a ventilated air gap is 2-3 times more expensive than solid insulation, which is no longer determined by energy efficiency, since the insulation layer is the same in both options, but by the cost of the protective and finishing layer. At the same time, in the total cost of the insulation system, the price of the insulation itself can be (especially for the above incorrect options for using cheap non-plate materials) only 5-10%. Considering the facade insulation, one cannot help but dwell on the insulation of the premises from the inside. Such is the property of our people that in all practical undertakings, regardless of objective laws, they are looking for extraordinary ways, be it social revolutions or the construction and reconstruction of buildings. Internal insulation attracts everyone with its cheapness - the cost is only for a heater, and its choice is quite wide, since there is no need for strict compliance with reliability criteria, therefore, the cost of a heater will no longer be high with the same thermal insulation performance, the finish is minimal - any sheet material and wallpaper labor costs are minimal. The usable volume of the premises is reduced - these are trifles compared to the constant thermal discomfort. These arguments would be good if such a decision did not contradict the laws of formation of the normal heat and moisture regime of structures. And this regime can be called normal only if there is no accumulation of moisture in it during the cold season (the duration of which for Kyiv is 181 days - exactly half a year). If this condition is not met, that is, when the vaporous moisture condenses, which enters the outer structure under the action of heat and mass transfer forces, the materials of the structure and, above all, the heat-insulating layer become wet in the thickness of the structure, the thermal conductivity of which increases, which causes even greater intensity further condensation of vaporous moisture. The result is a loss of thermal insulation properties, the formation of mold, fungi and other troubles.

Graphs 1, 2 show the characteristics of the heat and moisture conditions of the walls during their internal insulation. A claydite-concrete wall is considered as the main wall, and foam concrete and PSB-S are the most commonly used as heat-insulating layers. For both options, there is an intersection of the lines of partial pressure of water vapor e and saturated water vapor E, which indicates the possibility of vapor condensation already in the intersection zone, which is located at the boundary between the insulation and the wall. What this decision leads to in buildings already in operation, where the walls were in an unsatisfactory heat and moisture regime (photo 3) and where they tried to improve this regime with a similar solution, can be seen in photo 4. A completely different picture is observed when the terms are changed, that is, the placement of a layer of insulation on front side of the wall (graph 3).

Chart #1

Chart #2

Chart #3

It should be noted that PSB-S is a material with a closed-cell structure and a low vapor permeability coefficient. However, for this type of materials, as well as when using mineral wool boards (Figure 4), the mechanism of thermal moisture transfer created during insulation ensures the normal moisture state of the insulated wall. Thus, if it is necessary to choose internal insulation, and this may be for buildings with an architectural value of the facade, it is necessary to carefully optimize the composition of thermal insulation in order to avoid or at least minimize the consequences of the regime.

Chart No. 4

Walls of buildings of well brickwork

The heat-insulating properties of the walls are determined by the layer of insulation, the requirements for which are mainly determined by its heat-insulating characteristics. The strength properties of the insulation, its resistance to atmospheric influences for this type of structures do not play a decisive role. Therefore, PSB-S slabs with a density of 15-30 kg / m3, soft mineral wool slabs and mats can be used as insulation. When designing walls of such a structure, it is necessary to calculate the reduced resistance to heat transfer, taking into account the effect of solid brick lintels on the integral heat flux through the walls.

Walls of buildings of a frame-monolithic scheme.

A characteristic feature of these walls is the possibility of providing a relatively uniform temperature field over a sufficiently large area of the inner surface of the outer walls. At the same time, the load-bearing columns of the frame are massive heat-conducting inclusions, which necessitates mandatory verification of compliance of temperature fields with regulatory requirements. The most common as the outer layer of the walls of this scheme is the use of brickwork in a quarter of a brick, 0.5 bricks or one brick. At the same time, high-quality imported or domestic bricks are used, which gives the buildings an attractive architectural appearance (photo 5).

From the point of view of the formation of a normal humidity regime, the most optimal is the use of an outer layer of a quarter of a brick, but this requires high quality of both the brick itself and the masonry work. Unfortunately, in domestic practice, for multi-storey buildings, reliable masonry even of 0.5 bricks cannot always be ensured, and therefore the outer layer of one brick is mainly used. Such a decision already requires a thorough analysis of the thermal and moisture regime of structures, only after which it is possible to make a conclusion about the viability of a particular wall. Foam concrete is widely used as a heater in Ukraine. The presence of a ventilated air layer allows you to remove moisture from the insulation layer, which guarantees the normal heat and moisture conditions of the wall structure. The disadvantages of this solution include the fact that in terms of thermal insulation, the outer layer of one brick does not work at all, the outer cold air directly washes the foam concrete insulation, which necessitates high requirements for its frost resistance. Taking into account the fact that foam concrete with a density of 400 kg/m3 should be used for thermal insulation, and in the practice of domestic production there is often a violation of technology, and the foam concrete used in such design solutions has an actual density higher than specified (up to 600 kg/m3), this design solution requires careful control during the installation of walls and upon acceptance of the building. Currently developed and in

pre-factory readiness (a production line is being built) are promising heat-sound-proof and, at the same time, finishing materials that can be used in the construction of the walls of buildings of a frame-monolithic scheme. These materials include slabs and blocks based on the Siolit ceramic mineral material. A very interesting solution for the construction of external walls is translucent insulation. At the same time, such a heat and moisture regime is formed in which there is no condensation of vapors in the thickness of the insulation, and translucent insulation is not only thermal insulation, but also a source of heat in the cold season.

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