Structures of external walls of civil and industrial buildings
The structures of external walls of civil and industrial buildings are classified according to the following criteria:
1) by static function:
a) load-bearing;
b) self-supporting;
c) non-load-bearing (mounted).
In Fig. 3.19 shown general form these types of external walls.
Load-bearing external walls perceive and transfer to the foundations their own weight and loads from adjacent building structures: floors, partitions, roofs, etc. (at the same time they perform load-bearing and enclosing functions).
Self-supporting external walls perceive vertical load only from their own weight (including the load from balconies, bay windows, parapets and other wall elements) and transfer them to the foundations through intermediate load-bearing structures - foundation beams, grillages or plinth panels (at the same time they perform load-bearing and enclosing functions).
Non-load-bearing (curtain) external walls floor by floor (or through several floors) they rest on adjacent supporting structures of the building - floors, frames or walls. Thus, curtain walls perform only an enclosing function.
Rice. 3.19. Types of external walls according to static function:
a – load-bearing; b – self-supporting; c – non-load-bearing (suspended): 1 – building floor; 2 – frame column; 3 – foundation
Load-bearing and non-load-bearing external walls are used in buildings of any number of floors. Self-supporting walls rest on their own foundation, so their height is limited due to the possibility of mutual deformations of the external walls and internal structures of the building. The taller the building, the greater the difference in vertical deformations, so, for example, in panel houses It is allowed to use self-supporting walls with a building height of no more than 5 floors.
The stability of self-supporting external walls is ensured by flexible connections with the internal structures of the building.
2) According to the material:
A) stone walls They are built from brick (clay or silicate) or stones (concrete or natural) and are used in buildings of any number of storeys. Stone blocks are made from natural stone (limestone, tuff, etc.) or artificial (concrete, lightweight concrete).
b) Concrete walls made of heavy concrete of class B15 and higher with a density of 1600 ÷ 2000 kg/m 3 (load-bearing parts of the walls) or light concrete of classes B5 ÷ B15 with a density of 1200 ÷ 1600 kg/m 3 (for thermal insulation parts of the walls).
For the production of lightweight concrete, artificial porous aggregates (expanded clay, perlite, shungizite, agloporite, etc.) or natural lightweight aggregates (crushed stone from pumice, slag, tuff) are used.
When constructing non-load-bearing external walls, cellular concrete (foam concrete, aerated concrete, etc.) of classes B2 ÷ B5 with a density of 600 ÷ 1600 kg/m 3 is also used. Concrete walls are used in buildings of any number of floors.
V) Wooden walls used in low-rise buildings. For their construction, pine logs with a diameter of 180 ÷ 240 mm or beams with a section of 150x150 mm or 180x180 mm are used, as well as board or glue-plywood panels and panels with a thickness of 150 ÷ 200 mm.
G) walls made of non concrete materials mainly used in the construction of industrial buildings or low-rise civil buildings. Structurally, they consist of outer and inner cladding made of sheet material (steel, aluminum alloys, plastic, asbestos cement, etc.) and insulation (sandwich panels). Walls of this type are designed as load-bearing only for one-story buildings, and for larger numbers of floors - only as non-load-bearing.
3) according to a constructive solution:
a) single-layer;
b) two-layer;
c) three-layer.
The number of layers of the building’s external walls is determined based on the results of thermal engineering calculations. To comply with modern standards for heat transfer resistance in most regions of Russia, it is necessary to design three-layer external wall structures with effective insulation.
4) according to construction technology:
a) by traditional technology Hand-laid stone walls are being erected. In this case, bricks or stones are laid in rows in layers cement-sand mortar. The strength of stone walls is ensured by the strength of the stone and mortar, as well as the mutual bandaging of vertical seams. To further increase the load-bearing capacity of masonry (for example, for narrow walls), horizontal reinforcement is used welded mesh after 2 ÷ 5 rows.
The required thickness of stone walls is determined by thermal calculations and linked to standard sizes bricks or stones. Brick walls with a thickness of 1; 1.5; 2; 2.5 and 3 bricks (250, 380, 510, 640 and 770 mm, respectively). Walls made of concrete or natural stones when laying 1 and 1.5 stones, the thickness is 390 and 490 mm, respectively.
In Fig. Figure 3.20 shows several types of solid masonry made of brick and stone blocks. In Fig. Figure 3.21 shows the design of a three-layer brick wall with a thickness of 510 mm (for the climatic region of the Nizhny Novgorod region).
Rice. 3.20. Types of solid masonry: a – six-row brickwork; b – two-row brickwork; c – masonry made of ceramic stones; d and e – masonry made of concrete or natural stones; e – stone masonry cellular concrete With external cladding brick
The inner layer of the three-layer stone wall supports the floors and load-bearing structures of the roof. The outer and inner layers of brickwork are connected to each other reinforcing mesh with a vertical pitch of no more than 600 mm. The thickness of the inner layer is assumed to be 250 mm for buildings with a height of 1 ÷ 4 floors, 380 mm for buildings with a height of 5 ÷ 14 floors and 510 mm for buildings with a height of more than 14 floors.
Rice. 3.21. Three-layer stone wall:
1 – internal load-bearing layer;
2 – thermal insulation layer;
3 – air gap;
4 – outer self-supporting (cladding) layer
b) fully assembled technology used in the construction of large-panel and volumetric block buildings. In this case, installation individual elements buildings are carried out by cranes.
The external walls of large-panel buildings are made of concrete or brick panels. Panel thickness – 300, 350, 400 mm. In Fig. Figure 3.22 shows the main types of concrete panels used in civil engineering.
Rice. 3.22. Concrete panels of external walls: a – single-layer; b – two-layer; c – three-layer:
1 – structural and thermal insulation layer;
2 – protective and finishing layer;
3 – load-bearing layer;
4 – thermal insulation layer
Volume-block buildings are buildings of increased factory readiness, which are assembled from separate prefabricated block-rooms. The outer walls of such volumetric blocks can be one-, two-, or three-layer.
V) monolithic and prefabricated-monolithic construction technologies allow the construction of one-, two- and three-layer monolithic concrete walls.
Rice. 3.23. Prefabricated monolithic external walls (in plan):
a – two-layer with an outer layer of thermal insulation;
b – the same, with an inner layer of thermal insulation;
c – three-layer with an outer layer of thermal insulation
When using this technology, the formwork (mold) is first installed into which the concrete mixture is poured. Single-layer walls are made of lightweight concrete with a thickness of 300 ÷ 500 mm.
Multilayer walls are made prefabricated monolithic using an outer or inner layer of stone blocks made of cellular concrete. (see Fig. 3.23).
5) according to the location of window openings:
In Fig. 3.24 shown various options location of window openings in the external walls of buildings. Options A, b, V, G used in the design of residential and public buildings, option d– when designing industrial and public buildings, option e– for public buildings.
From considering these options, it can be seen that functional purpose building (residential, public or industrial) determines the design of its external walls and appearance generally.
One of the main requirements for external walls is the necessary fire resistance. According to the requirements of fire safety standards, load-bearing external walls must be made of fireproof materials with a fire resistance limit of at least 2 hours (stone, concrete). The use of fire-resistant load-bearing walls (for example, wooden plastered walls) with a fire resistance limit of at least 0.5 hours is allowed only in one- and two-story houses.
Rice. 3.24. Location of window openings in the external walls of buildings:
a – wall without openings;
b – wall with a small number of openings;
V - panel wall with openings;
d – load-bearing wall with reinforced partitions;
d – wall with hanging panels;
e – fully glazed wall (stained glass)
High requirements for the fire resistance of load-bearing walls are caused by their main role in the safety of the building, since the destruction of load-bearing walls in a fire causes the collapse of all structures resting on them and the building as a whole.
Non-load-bearing external walls are designed to be fireproof or difficult to burn with lower fire resistance limits (from 0.25 to 0.5 hours), since the destruction of these structures in a fire can only cause local damage to the building.
The thickness of the external walls is selected according to the largest of the values obtained as a result of static and thermal calculations, and is assigned in accordance with the design and thermal characteristics of the enclosing structure.
In fully prefabricated concrete housing construction, the design thickness outer wall linked to the nearest larger value from the unified series of external wall thicknesses adopted in the centralized production of molding equipment: 250, 300, 350, 400 mm for panel buildings and 300, 400, 500 mm for large-block buildings.
The calculated thickness of 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 sizes of 250×120×65 or 250×120×88 mm (modular brick), the thickness of the solid masonry walls is 1; 1.5; 2; 2.5 and 3 bricks (including 10 mm vertical joints between individual stones) are 250, 380, 510, 640, and 770 mm.
The structural thickness of a wall made of sawn stone or light concrete small blocks, the standardized dimensions of which are 390 × 190 × 188 mm, when laid in one stone is 390 and 1.5 - 490 mm.
The design 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, insulation and architectural and decorative qualities.
In accordance with modern requirements for 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 transport routes, small locally produced stones or monolithic concrete are used to build walls in combination with local insulation and local aggregates, which require only imported cement. In villages located near industrial centers, houses are designed with walls made of large blocks or panels manufactured at enterprises in this region. Currently, stone materials are increasingly used in the construction of houses on garden plots.
When designing low-rise buildings, two structural solutions for 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 using a solid masonry scheme, preference is given to less dense materials. This technique allows you to achieve minimum thickness walls by thermal conductivity and more fully use the load-bearing capacity of the material. Construction Materials high density is advantageous to use in combination with low-density materials (lightweight walls). The principle of constructing lightweight walls is based on the fact that the load-bearing functions are performed by a layer (layers) of high-density materials (γ > 1600 kg/m3), and the heat insulator is a low-density material. For example, instead of a solid outer wall made of clay brick 64 cm thick, you can use a lightweight wall structure made from a layer of the same brick 24 cm thick, with fiberboard insulation 10 cm thick. Such a replacement leads to a reduction in the weight of the wall by 2.3 times.
Artificial and natural small stones are used to make walls of low-rise buildings. Currently, artificial firing stones (solid clay bricks, hollow bricks, porous bricks and ceramic blocks) are used in construction; unfired stones ( sand-lime brick, hollow blocks made of heavy concrete and solid blocks made of light 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 hand-laying technology and taking into account maximum mechanization of work. The walls are laid out from stones with the gap between them filled with mortar. Cement-sand mortars are most often used. For laying internal walls, ordinary sand is used, and for external walls, low-density sand (perlite, etc.). Wall laying is carried out with mandatory compliance suture dressings(4.6) in rows.
As already noted, the width of the wall masonry is always a multiple of the number of brick halves. The rows facing the façade surface of the masonry are called front mile, and those facing inner side – inner mile. The rows of masonry between the inner and front versts are called forgettable. Bricks laid with the long side along the wall form spoon row, and the walls laid across - splice 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 butt rows. With uniform alternation of spoon and butt rows, a two-row (chain) masonry system is obtained (Fig. 4.5b). A less labor-intensive multi-row masonry system, in which one interlocking row of bricks binds five rows of spoons (Fig. 4.5a). In walls made of small blocks, erected using a multi-row system, one tying row ties two trussed rows of masonry (Fig. 4.5c).
Fig.4.5. Types of hand-made 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 unheated premises(Fig. 4.6a-g). In some cases, this masonry is used for the construction of external walls using a multi-row system (Fig. 4.6a-c, e). The double-row stone laying system is used only in necessary cases. 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 using a chain laying system.
Lightweight external walls are designed in two types - with insulation between two solid masonry walls 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 releases of anchor stones, walls with vertical diaphragms made of stones (well masonry) and walls with horizontal diaphragms. The first option is used only in cases where lightweight concrete is used as insulation, which embeds 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 made from bulk materials (Fig. 4.6l) or from lightweight concrete stones. Solid masonry walls with an air gap (Fig. 4.6m) also belong to the category of lightweight walls, since the closed air gap acts as an insulation layer. It is advisable to take the thickness of the layers equal to 2 cm. Increasing the layer practically does not increase its thermal resistance, and reducing it sharply reduces the effectiveness of such thermal insulation. More often, an air gap is used in combination with insulation boards (Fig. 4.6k, o).
Fig. 4.6, Options for manual masonry of walls of low-rise residential buildings: a), b) - solid external walls made of brick; c) – solid internal brick wall; e), g) – solid external 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 sheet cladding; 3 – artificial stone; 4 – slab insulation; 5 – air gap; 6 – vapor barrier; 7 – wooden antiseptic strip; 8 – backfill; 9 – solution diaphragm; 10 – lightweight concrete; 11 – natural frost-resistant stone
To insulate stone walls on the street side, rigid slab insulation made of lightweight concrete, foam glass, fiberboard in combination with weather-resistant and durable cladding (asbestos cement sheets, boards, etc.) is used. The option of insulating walls from the outside is effective only if there is no access of cold air to the contact area of the load-bearing layer with the insulation layer. To insulate the external walls on the room side, 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 the distance”. The slabs are attached to the wall with metal zigzag brackets or nailed to antiseptic wooden slats. The open surface of the insulation layer is covered with sheets of dry plaster. Between them and the insulation layer, a layer of vapor barrier made of glassine, polyethylene film, metal foil, etc. must be placed.
Study and analyze the above material and answer the proposed question.
Question 4.2. Can rows of bricks laid with the long side along the wall be called bonded rows?
4.2. answer: yes
Vertical structural elements of a building that separate rooms from external environment and dividing the building into separate rooms are called walls. They perform enclosing and load-bearing (or only the first) functions. They are classified according to various criteria.
By location - external and internal.
Exterior walls- the most complex building structure. They are exposed to many and varied forceful and non-forceful influences. The walls bear their own weight, permanent and temporary loads from floors and roofs, exposure to wind, uneven deformations of the base, seismic forces, etc. outside External walls are exposed to solar radiation, precipitation, variable temperatures and humidity of outside air, external noise, and from the inside - to heat flow, water vapor flow, and noise.
Performing the functions of an external enclosing structure and compositional element facades, and often the supporting structure, the outer 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 for the enclosed premises, and have decorative qualities.
The design of the external wall must satisfy the economic requirements of minimum material consumption and cost, since external walls are the most expensive structure (20-25% of the cost of 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, and structures of open rooms.
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.
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 various types: temperature, sedimentary, antiseismic, etc.
Internal walls are divided into:
Inter-apartment;
Indoor (walls and partitions);
Walls with ventilation ducts(near the kitchen, bathrooms, etc.).
Depending on the adopted structural system and building layout, the external and internal walls of the building are divided into load-bearing, self-supporting and non-load-bearing (Fig. 84).
Fig.84. Wall structures:
a - load-bearing; b – self-supporting; c – mounted
Partitions- These are vertical, usually non-load-bearing fences that divide the internal volume of a building into adjacent rooms.
They are classified according to the following criteria:
By location - interior, inter-apartment, for kitchens and plumbing units;
By function - blind, with openings, incomplete, that is, not reaching
By design - solid, frame, sheathed on the outside with sheet material;
According to the installation method - stationary and transformable.
Partitions must meet the requirements of strength, stability, fire resistance, sound insulation, etc.
Bearers walls, in addition to the vertical load from their own mass, perceive and transmit to the foundations loads from adjacent structures: floors, partitions, roofs, etc.
Self-supporting walls take vertical load only from their own mass (including the load from balconies, bay windows, parapets and other wall elements) and transfer it to the foundations directly or through plinth panels, rand beams, grillage or other structures.
Non-load bearing the walls, floor by floor (or across several floors), are supported on adjacent internal structures of the building (floors, walls, frame).
Load-bearing and self-supporting walls perceive horizontal loads along with vertical ones, being vertical elements of rigidity of structures.
In buildings with non-load-bearing external walls, the functions of vertical stiffening elements are performed by the frame, internal walls, diaphragms or stiffening trunks.
Load-bearing and non-load-bearing external walls can be used in buildings of any number of floors. 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 finishing 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 ensured by flexible connections with internal structures.
Load-bearing external walls are used in buildings of various heights.
The maximum number of storeys of a load-bearing wall depends on the load-bearing capacity and deformability of its material, design, the nature of the relationships with internal structures, as well as on economic considerations. For example, the use of lightweight concrete panel walls is advisable in buildings up to 9-12 floors high, load-bearing brick exterior walls in mid-rise buildings (4-5 floors), and steel lattice shell walls in 70-100-story buildings.
By design - small-element (brick, etc.) and large-element(from large panels, blocks, etc.)
Based on the mass and degree of thermal inertia, the outer walls of buildings are divided into four groups - massive (more than 750 kg/m2), medium massive (401-750 kg/m2), light (150-400 kg/m2), especially light (150-400 kg/m2).
Based on the material, the main types of wall structures are distinguished: concrete, stone made of non-concrete materials and wood. According to the building system, each type of wall contains several types of structures: concrete walls- from monolithic concrete,
large blocks or panels; stone walls - hand-made, walls made of stone blocks and panels; walls made of non-concrete materials - half-timbered and panel frame and
frameless; wooden walls- chopped from logs or beams, frame-sheathing, frame-panel, panel and panel. Concrete and stone walls are used in buildings of various heights and for various static functions in accordance with their role in structural system building. Walls made of non-concrete materials are used in buildings of various heights only as a non-load-bearing structure.
External walls can be single-layer or layered construction.
Single layer e walls are erected from panels, concrete or stone blocks, monolithic concrete, stone, brick, wooden logs or beams. IN layered walls execution different functions entrusted to various materials. Strength functions are provided by concrete, stone, wood: durability functions are provided by concrete, stone, wood or sheet material(aluminum alloys, clad steel, asbestos cement, etc.); thermal insulation functions - effective insulation materials (mineral wool boards, fiberboard, expanded polystyrene, etc.); vapor barrier functions - roll materials(pasting roofing felt, foil, etc.), dense concrete or mastics; decorative functions - various facing materials. An air gap may 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 cladding layer of the wall.
Single- and multi-layer wall structures can be made fully prefabricated or using traditional techniques.
Wall structures must meet the requirements of capital construction, strength and stability. The thermal insulation and sound insulation capacity of walls is established on the basis of thermal and sound insulation calculations.
The thickness of the external walls is selected according to the largest of the values obtained as a result of static and thermal calculations, and is assigned in accordance with the design and thermal characteristics of the enclosing structure.
Rice. 85. Homogeneous brickwork:
a – six-row dressing system; b – chain (double-row dressing system).
Fig.86. Well masonry brick walls:
a – with horizontal diaphragms made of cement-sand mortar; b – the same, from interlocking bricks arranged in a checkerboard pattern; c – the same, located in the same plane; d – axonometry of the masonry.
Rice. 87. External wall panels:
a – single-layer; b – two-layer; c – three-layer; 1 – structural and thermal insulating concrete; 2 – protective and finishing layer; 3 – structural concrete; 4 – effective insulation.
A study of the old residential buildings of Moscow, St. Petersburg, Kaliningrad, Kaluga and other Russian cities showed that within the long-established central part of the city the main objects overhaul and reconstructions are two- to five-story residential buildings built at the beginning of the last century. The variety of structural forms of objects of the old stock is distinguished by a relatively small assortment: material - rubble stone, brick, wood; construction technology - manual labor.
Constructive decisions houses old building
Foundations in normal soils were, as a rule, built as strip foundations from torn rubble stone, or less often from burnt iron ore bricks with a complex mortar. On weak, unevenly compressed soils, for example, in St. Petersburg, foundations were often built on an artificial foundation - on wooden stilts or beds.
Load-bearing walls of residential buildings were laid out on heavy cement and lime mortars made of solid red brick of the highest (by today's standards) quality. As a result, they have been preserved much better than other types of structures. The thickness of the walls ranges from 2.5 to 4 bricks. The rigid connection of the longitudinal and transverse stone walls of the buildings was ensured by installing hidden connections made of the strongest wrought iron. In general, civil buildings built before the revolution are characterized by a wide variety of design solutions and the presence of a significant number of transverse walls, ensuring high spatial rigidity of the load-bearing frame. The vertical load in these buildings is usually carried by external and internal longitudinal walls. Occasionally there are load-bearing wooden half-timbered partitions. Interior partitions were made of wood (plastered on both sides with shingles) or brick.
The main type of floors in old stone buildings is the floor wooden beams with a roll of plates or boards. The pitch of load-bearing beams according to the pre-revolutionary “standard position” was usually assigned to 1-1.5 m. The floors in the living area are wooden, parquet or linoleum. In wet rooms and in the area of staircases and elevators - from Metlakh tiles, or cement with iron reinforcement.
Rafter system pitched roofs were built from layered logs and hanging type. The design of stairs in most stone buildings is made in the form of stone or concrete steps laid on steel stringers. In staircases with one stringer per flight, one end of the steps was embedded in the masonry of the walls.
Typification of design solutions of the old foundation
A number of research organizations are engaged in research and typification of design solutions in the field of major repairs and reconstruction of old residential buildings. The research results are compiled into a single system and sorted into groups and categories according to a variety of classification criteria.
In Fig. 1. shows a schematic plan and section of a residential building with the designation structural elements and technical and economic parameters that are of greatest interest to designers and builders working in the field of reconstruction of old buildings.
Fig.1. Schematic plan and section of an old residential building with the designation of the main typification parameters
Analysis of the data accumulated by engineers and builders during the research process allows us to draw the following conclusions:
1. The most common two-bay scheme of residential buildings (from the 1st internal wall), less often - three-span (with 2 internal walls). The share of these schemes accounts for 53-54%, i.e. more than half of all houses.
2. The “clear” distance between load-bearing walls is:
- in Moscow from 4 to 7 m - 51%; from 7 or more - 46.9%;
- in St. Petersburg from 4 to 7 m - 77.1%; from 7 or more - 16.7%.
3. The most common distances between the axes of external walls:
- in Moscow from 2 to 2.5 m - 80.5%;
- in St. Petersburg from 1.75 to 2.75 m - 87.9%.
4. External walls in their upper part, at the level attic floor, have a thickness of 60 to 90 cm, and internal walls - from 40 to 80 cm.
5. The thickness of ceilings and floors ranges from 33 to 40 cm (89.6%).
6. Floor heights also vary widely. However, in Moscow, buildings with floor heights from 3 to 4 m are 93.1%, and in St. Petersburg - 84.3%.
The considered design characteristics of old residential buildings should form the basis for the development of industrial engineering solutions.
Table 3.2 shows a diagram showing the dependence and variability of design solutions and methods for reconstructing old housing stock. In the practice of reconstruction work, which takes into account the physical wear and tear of non-replaceable structures, several solutions are used: without changing the structural design and with changing it; without changing the building volume, with the addition of floors and small extensions.
Table 3.2
The first option involves restoring the building without changing the building volume, but with the replacement of floors, roofing and other structural elements. In this case, a new layout is created that meets modern requirements and requests from social groups of residents. The reconstructed building must preserve the architectural appearance of the facades, and its operational characteristics must be brought up to modern regulatory requirements.
Options with changes in design schemes provide for an increase in the construction volume of buildings by: adding volumes and expanding the building without changing its height; superstructures without changing the plan dimensions; extensions of several floors, extensions of additional volumes with changes in the dimensions of the building in plan. This form of reconstruction is accompanied by redevelopment of premises.
Depending on the location of the building and its role in the development, the following reconstruction options are carried out: with preservation of residential functions; with partial repurposing and complete repurposing of the building's functions.
Reconstruction of residential buildings should be carried out comprehensively, including, along with the reconstruction of the intra-block environment, its landscaping, improvement and restoration utility networks and so on. During the reconstruction process, the range of built-in premises is revised in accordance with the standards for the provision of primary care institutions to the population.
In the central areas of cities, buildings being reconstructed may contain built-in city-wide and commercial establishments periodic and constant maintenance. The use of built-in spaces transforms residential buildings into multifunctional buildings. Non-residential premises are located on the first floors of houses located along the red building lines.
In Fig. 3.5 shows structural and technological options for the reconstruction of buildings with preservation ( A) and with change ( b,V) structural diagrams, without changing volumes and with their increase (superstructure, extension and expansion of the planned dimensions of buildings).
Rice. 3.5. Reconstruction options for early residential buildings A- without changing the design scheme and construction volume; b- with the addition of small volumes and the transformation of the attic floor into an attic; V- with the addition of floors and extension of volumes; G- with an extension of the building to the end of the building; d, f- with the construction of buildings; and- with extension of volumes of curvilinear shapes
A special place in the reconstruction of urban centers should be given to the rational development of underground space adjacent to buildings, which can be used as shopping centers, parking lots, small businesses, etc.
The main structural and technological method of reconstructing buildings without changing the design scheme is to preserve the permanent structures of external and internal walls, staircases with the installation of heavy-duty floors. If there is a significant degree of wear and tear on the internal walls as a result of frequent redevelopment with the construction of additional openings, relocation of ventilation ducts, etc. reconstruction is carried out by installing built-in systems while preserving only the external walls as load-bearing and enclosing structures.
Reconstruction with a change in the building volume involves the installation of built-in permanent systems with independent foundations. This circumstance makes it possible to add several floors to buildings. In this case, the structures of external and, in some cases, internal walls are freed from the loads of the overlying floors and turned into self-supporting enclosing elements.
When reconstructing a building by widening it, constructive and technological options are possible for partially using existing foundations and walls as load-bearing ones with redistribution of loads from the floors being built on to the external elements of buildings.
The principles of reconstruction of buildings built later (1930-40s) are dictated by the simpler configuration of sectional type houses, the presence of floors made of small-piece reinforced concrete slabs or wooden beams, as well as the smaller thickness of external walls. The main methods of reconstruction consist in the addition of elevator shafts and other small volumes in the form of bay windows and inserts, the addition of floors and attics, and the construction of remote low-rise extensions for administrative, commercial or household purposes.
Increasing the comfort of apartments is achieved through complete redevelopment with replacement of floors, and an increase in the volume of the building as a result of the superstructure ensures an increase in the building density of the quarter.
The most typical methods of reconstruction of buildings of this type are the replacement of floors with prefabricated or monolithic structures with complete redevelopment, as well as an additional superstructure of 1-2 floors. In this case, the superstructure of buildings is carried out in cases where the condition of the foundations and wall fencing ensures the perception of changed loads. As experience has shown, buildings of this period allow for the addition of up to two floors without strengthening the foundations and walls.
In case of increasing the height of the superstructure, built-in building systems of prefabricated, prefabricated and monolithic structures are used.
The use of built-in systems makes it possible to implement the principle of creating large overlapping areas that facilitate the implementation of flexible room layouts.