Sectional residential buildings
Corridor residential buildings. In corridor residential buildings, apartments are located on both sides of the corridor. Such houses can be apartment buildings for permanent residence and hostels and hotels for temporary residence. In corridor houses, vertical communications are stairs (with a building height of up to 5 floors) and stairs with elevators for houses of 6 floors and above. The corridor layout allows more economical use of vertical communications, providing an increase in the number of apartments per staircase and elevator, which is especially evident in high-rise buildings. As a rule, residential corridor buildings have a meridian orientation, which makes it possible to meet the requirements for insolation. Corridors in such houses should be of sufficient width, illumination and ventilation. Corridors are illuminated through window openings from one end (with a corridor length of up to 24 m) and from two ends (with a length of up to 48 m). For longer lengths, light halls are arranged at a distance of no more than 24 m from each other.
Gallery residential buildings in terms of layout, they differ from the corridor ones in that the entrances to the apartments in such houses are arranged from the floor-by-floor open corridors-galleries, which are taken out beyond the outer edge of one of the longitudinal walls. Apartments in gallery houses are located on one side of the gallery and, accordingly, have through ventilation. It is advisable to build this type of houses in areas where it is necessary to protect residential premises from overheating. Apartments in gallery houses adjoin galleries with their auxiliary rooms. The vertical transport hub in gallery buildings adjoins the galleries or at the ends, or in the middle part, and is often carried out beyond the dimensions of the residential building. In multi-storey gallery buildings, there must be at least two nodes of vertical transport in the form of evacuation stairs.
3. Space-planning solutions of apartments, staircase and elevator nodes, entrance nodes
The arrangement of premises of a given size and shape in one building or a complex of buildings, subordinate to the functional, technical, architectural, artistic and economic requirements, is called the volumetric planning solution of a building or a complex of buildings.
The premises in the building, depending on their role in the implementation of the main functional process, are divided into:
The main premises designed to perform the main functions of the building;
Utility (auxiliary) premises designed to perform auxiliary functions that contribute to the implementation of the main functional;
Communication rooms that provide connections between rooms. Communications are horizontal (corridors, galleries, walkways, foyers, lobbies) and vertical (stairs, elevators, escalators, ramps).
Requirements for external wall panels and their joints. General information about the force effects of horizontal and vertical joints of external panel walls
Any design must meet the requirements:
Strength,
Longevity,
Minimum deformability,
Thermal insulation,
Interactions with internal building structures
Architectural and decorative properties
The connections between the outer layers of the walls are designed to be rigid or flexible.
Strength requirements are met by the use of materials with high compressive strength for the inner layers of structures. Durability requirement and crack resistance of the outer layer, which is satisfied by the use of high classes or grades of wall material for compressive strength (see above), its compliance with the requirements for the grade of wall material for frost resistance for each climatic Region Stability. The joint work of external and internal walls is provided in brick walls by bandaging the masonry of the walls, in concrete panel - concrete discrete keyway ties
Variants of arrangement of horizontal joints of panels of internal walls. General information about the force effects at these joints
Platform
Contact;
Contact - platform;
Monolithic platform
a - platform; b - contact; в - contact - platform; d - monolithic
Providing insulating properties of panel walls. Requirement for heat protection, moisture resistance and air tightness of the joints of external panel walls. Open, closed, drained joints. Their scope
The most critical and complex in execution in the structures of a large-panel building are the joints between the panels. There are many different solutions, but none of them meets all the requirements for joints: strength (rigid connection of wall panels with each other and with overlap), durability and tightness, heat and sound insulation, simplicity of the device and artistic expression. Structural solutions of joints can be classified according to the following features: according to the design of the outer zone (open, with a drainage tape and closed, protected with cement mortar and sealing mastics); by the method of embedding (insulated, with the laying of an effective insulation, and embedded in concrete); by the method of mating (welded, hinged, bolted self-wedging or keyway Design solutions of joints can be classified according to the following criteria:
By mating method (welded, looped, bolted, self-wedging or keyed),
By the method of embedding (insulated, with the laying of an effective insulation, and with monolithic concrete),
Joints of closed, drained and open types are used.
By the arrangement of the outer zone (or along the edges of the panel cutting),
Open and closed
A drained joint is used as a variant of a closed joint protected with cement mortar and sealing mastics.
The choice of the type is determined by the design of the external wall panels and the climatic zoning of the country according to the design winter temperature and the rains accompanied by the wind. The correct choice of the type of joints favors the drying regime of the outer walls during the operation of the building. The insulating properties of the joints are ensured by their labyrinthine section and elastic sealing of the outer joints, which compensates for the tendency to open in winter. Condensation is prevented by the drying regime of the wall, supported by natural ventilation through the pores of the building materials, and the removal of moisture that has penetrated beyond the insulation zone. Condensate flows down the decompression channels in the lateral edges of the panels and is then discharged from the wall through drainage holes in drained joints or through open mouths in open joints.
21. Overlapping buildings from large-sized elements. Purpose, requirements for them, classification by location and construction technology
Classification of roofs by material, by the method of execution, by the presence of space between the roof and the premises of the building, by the slope of the roof, by the thermal characteristics, by the type of roof, by the organization of the spillway from the building
The roof is a solid part of the building related to the load-bearing structures, located on top and protecting the interior from the penetration of atmospheric precipitation.
The roof must be strong and stable, have hydro and thermal insulation properties. When building, be sure to take into account fire regulations. In addition, the roof is a decoration of the house, it can completely change its appearance - give it a modern or old style, make it visually taller and more airy, or, conversely, reliable and stable.
Classification by the way of structure
There are two types of roofs: attic and combined.
An attic roof is a structure that consists of an outer roof and the building trusses that support it. Sheathing or flooring is usually placed on the beams. The slope of the roof can be different, it depends on two conditions: the material used for the roof, and the climate of the natural area in which the house is being built.
With a large amount of precipitation, the roof slope is made at an angle of 45 ° or more, and if dry weather and strong winds prevail, then the slope should not exceed 30 °. When piece materials are used for the roof, the angle cannot be made less than 22 °. For roll materials, an angle of 5 to 25 ° will be optimal, and for asbestos-cement sheets and tiles - 25-35 ° or more. As the slope of the roof increases, the material consumption and overall cost increase.
The combined roof is a special flooring that performs the functions of waterproofing, placed on the attic floor and practically does not have a slope. The material for it is several layers of roofing material, smeared with bitumen mastic. The liquid is drained from it through the internal drains.
Classification according to the level of thermal insulation
Roofs are warm and cold. The presence of an attic in the structure defines them as warm, since its device provides thermal insulation due to the air space formed by the roof surface, outer walls and the overlap of the upper floor. It protects the building from cold, provides ventilation and moisture exchange of various structural elements. Also, its device significantly increases the reliability and service life of the house, but the total cost of construction rises because the attic is not included in the number of residential premises.
In this case, it is possible to organize an attic, which is a living room located directly under the roof, and its walls are the side surfaces of the roof. The distance from the crown to the floor of the attic room must be at least 1.5 m. Thus, the entire interior space is used for housing.
Cold roofs without an attic are usually built over unheated buildings, sheds and other outbuildings. Their functions include only direct protection from atmospheric precipitation.
Classification by shape
Roofs are pitched, gable, broken, hip, hipped and cruciform. A ramp is a sloped roof plane. Crossing, they create the ridge of the roof. The angle formed by the slopes of the roof and gable is called the valley.
Shed roofs are roofs with one inclined surface. They rest on two walls of different heights. The slope is usually directed upwind to protect the house from rain and snow. In addition, pitched roofs allow maximum use of the interior space of the building.
Gable - this is a classic option for small cottages. The roof is formed by two slopes directed in opposite directions.
Broken roofs are erected when building a house with an attic. They are not two, but four slopes connected at an obtuse angle. This type of roof is often used in individual construction.
Hip is a hipped roof with triangular slopes on the end sides.
Hip roofs are roofs with four slopes in the form of identical triangles, converging at one point.
Power loads and impacts on roofs. Requirements for the design of roofs. The layers that make up the roof and their purpose
Rice. 1. External influences on the coating
1-constant loads (dead weight); 2 - temporary loads (snow, operational loads); 3 - wind - pressure; 4 - wind suction; 5, 9 - impact of ambient temperatures; 6 - atmospheric moisture (precipitation, air humidity); 7 - chemically aggressive substances contained in the air; 8 - solar radiation; 10 - moisture contained in the air of the attic space
Structural elements of attic prefabricated reinforced concrete roofs. Their classification according to the method of removing air from the exhaust ventilation system through the roof structure, depending on the type and method of waterproofing the attic covering
Roofs made of prefabricated reinforced concrete panels are unexploited and maintained, attic and attic. Prefabricated reinforced concrete roofs are of six types: 1 - attic with waterproofing with mastic or paint compounds (rollless roof) (Fig. 14, c, d), 2 - attic with a roof made of roll materials; 3 - non-attic made of single-layer panels made of lightweight or cellular concrete; 4 - attic panels of multi-layer complex panels, consisting of two reinforced concrete panels, between which an effective heat-insulating material is laid; 5 - non-attic with load-bearing panels made of heavy concrete, on which slabs of effective insulating materials are laid; 6 - non-attic construction of a multi-layer structure with a backfill insulation and a screed for a roof made of rolled materials.
Organization of drainage from the roof. Roof slope options for flat roofs
34. Operated roof-terraces
Operated roof settles over both attic and non-attic floors. It can be arranged over the entire building or part of it. In modern multi-storey residential buildings, the roof is often used as a platform for recreation and other purposes. In this case, the exploited roof is called a terrace roof. The floor of the roof-terraces is designed flat or with a slope of no more than 1.5%, and the roof surface under it is designed with a slope of at least 3%. For the roof, the most durable materials are taken (for example, waterproofing). The number of layers of rolled carpet is taken one more than with an unexploited roof. A layer of hot mastic antiseptic with herbicides is applied to the surface of the carpet. They protect the carpet from the germination of plant roots from seeds and spores carried onto the roof by the wind.
The roof structure of roof-terraces is performed in the same way as for conventional roll roofs, but additional layers are arranged on top, which serve as the floor. The floor is made horizontal from individual slabs laid on a layer of gravel or coarse sand. Slabs can be reinforced concrete, natural stone, ceramics. A layer of gravel serves to protect the roll carpet, drainage and drainage of water to the gutters, which in this case are made with a flat lattice cover. The floor is arranged monolithic with a slight slope (asphalt concrete, mosaic, cement). Water drainage occurs along the outer surface of the floor to the valley, where the drain funnels are installed.
35. Classification of stairs by purpose, location, material, shape in plan, number of flights and platforms, size of structural elements, construction technology
Ladders are distinguished by purpose: main or main- for everyday use, subsidiary- spare, firefighters, emergency, service, employees for emergency evacuation, communications with the attic or basement, for approaching various equipment, etc., input- for the entrance, a building, usually arranged in the form of a wide entrance platform with steps By the number of marches: 1) Single-march 2) Two-march 3) Three-march. By the manufacturing method: in the form of a volumetric block; from sites together with marches; from separate platforms and marches; from small-sized elements in the form of individual steps, stringers, strut beams and slabs. By location in the building, they are distinguished: internal- public staircases located in stairwells or open in front lobbies - halls of public buildings, intra-apartment serving to connect residential premises within one apartment when located on several levels, and outdoor.
In the practice of mass construction, the riser height is usually taken equal to 140-170 mm, but not more than 180 mm and not less than 135 mm, and the width of the tread is taken equal to 280-300 mm, but not less than 250 mm. The width of the march is determined primarily by the fire safety requirements, as well as by the dimensions of the items carried along the stairs. The total width of the flights of stairs is taken depending on the number of people on the most populated floor at the rate of at least 0.6 m for 100 people The width of the landings must not be less than the width of the march. For main stairs with a run width of 1.05 m platforms must be at least 1.2 wide m. Landings in front of the entrances to the elevator with swing doors are assumed to be at least 1.6 liters wide.
A gap of at least 100 is left between the flights of stairs. mm, which is needed to pass the fire hose.
Requirements for designing stairs
Ladders are designed in compliance with building codes and regulations to ensure the Basic requirements for stairs: 1) strength, rigidity... Checked by calculation. 2) convenience, walking safety... Safety and convenience are ensured by a number of rules: a) ensuring the fatigue of the rise, provided by the size of the steps, convenient for setting the leg. The height of the riser is taken as 140-170 mm (standard - 150 mm), but not more than 180 mm and not less than 135 mm. The width of the tread is taken equal to 280-300 mm (standard - 300 mm), but not less than 250 mm; b) all the steps in the march must be the same size. c) number ascents in one march at least 3 (with less it is easy to stumble) - and no more than 18. d) natural lighting; Stairwells should generally have natural light through windows in the outer walls. In the stairwells, it is impossible to make any utility rooms or devices that could constrain the passages or serve as a source of fire. E) the fence (railing) must have a height of at least 0.9 m. up the stairs. 3) evacuation safety... a) the throughput of the staircase, depending on its width and slope, is ensured; b) the width of the staircase must be at least the width of the flight of stairs) between the flight and the staircase, a gap of at least 50 mm is left for the passage of a fire hose; d) fire safety reliability... Additional requirements are imposed on staircases in multi-storey buildings. They must be non-combustible, have a fire resistance limit of 1.5 hours.
Waterproofing of foundations
Zero-cycle civil buildings require a device waterproofing. The choice of a structural solution for waterproofing depends on
The nature of the impact of soil moisture
Situated room mode
Waterproofing materials of structures of the underground part of the building.
Moisture enters the foundation structures through the soil with atmospheric moisture or pound water. Capillary suction of moisture causes dampness of the walls of the basement and the first floor. An obstacle to this process is the device of horizontal and vertical waterproofing To protect the walls from capillary dampness in the foundations, waterproofing is arranged - horizontal and vertical According to the device method, waterproofing is distinguished:
Painting,
Plastering (cement or asphalt),
Cast asphalt,
Oleechnuyu (from roll materials)
Shell (metal).
In the absence of a basement in the building, horizontal waterproofing is laid at the level of the basement above the ground level mark (No. 1), and in the inner walls - at the level of the foundation cutoff. If there is a basement, a second level of horizontal waterproofing is laid under its floor. Horizontal waterproofing is made of two layers of roll material (roofing material on mastic, waterproofing, hydroglass, isoplastic, etc.) or a layer of asphalt concrete, cement with waterproofing additives.
Vertical waterproofing is designed to protect basement walls. Its design depends on the degree of moistening of the base soils. For dry soils, they are limited to two-time coating with hot bitumen. In wet soils, they arrange a moisture-resistant cement plaster with waterproofing pasted over with roll materials in two times. To protect vertical waterproofing, clamping walls made of bricks or asbestos-cement sheets are installed.
Variants of constructive solutions for cantilever and girder balcony slabs
48. Types of loggias. Constructive solutions for built-in and remote loggias of buildings from large-size elements
Balconies and loggias are open floor areas in residential and public buildings, connecting the internal spaces of the operated premises with the external environment. In emergency situations, they can be used to evacuate people. Loggias, unlike balconies on the sides, are fenced with walls, and can be either built-in to the volume of the building or external. Loggias are illuminated by the sun for less time than balconies, and their design is associated with an increase in the area of the outer walls.
Interfloor floors of loggias, in order to avoid the formation of a cold bridge, are separated from the main interfloor floors by an external wall panel or the gap is filled with insulating material, to which the window sill panel fits from above, and glazing bindings from below. The floor of the loggia is arranged in the same way as on balconies with a slope of 1-2% outward, and is made of tiles laid on cement mortar over a layer of waterproofing.
The slab of balconies and loggias along the outer perimeter must have a drip. The fencing of the loggias is made in the form of a metal lattice, the racks of which are sealed in the slots of the balcony slab, and the handrail is attached to the wall, and screens. Screens can be metal, asbestos-cement sheets, fiberglass, reinforced glass.
Floor slabs built-in loggias of panel buildings are supported on load-bearing side internal reinforced concrete walls, which require additional insulation structures in the form of separate additional panels of external walls or volumetric elements.
Feature of a constructive solution remote loggias lies in the danger of a difference in sedimentary deformations of the loggias and the building, especially with a high number of storeys, since the floors of such loggias rest on the side panel side walls - "cheeks".
Therefore, in multi-storey buildings, structures of hinged loggias are designed, the "cheeks" of which are attached to the transverse internal walls.
Side walls of outrigger loggias are designed to be load-bearing only in low and medium-rise buildings. At the same time, to ensure the joint settlement of the loggias and the building, the walls of the loggias are supported on the sections of the foundations of the transverse internal walls.
In frame panel buildings, the slabs of the balconies (loggias) work according to the beam scheme, relying on the consoles of the columns, thereby eliminating the transfer of the load to the outer walls. At the same time, vertical and horizontal joints of external wall panels are insulated according to the principle of a drained joint.
When designing balconies and loggias, it is necessary to ensure the drainage of water from the outer walls.
Variants of constructive solutions for external walls of volumetric blocks. Structures of joints, connections and parts
The constructive solution depends on the scheme of cutting these buildings into their constituent elements. Structural schemes of three-dimensional block buildings are more complicated than brick, block and panel buildings, since three-dimensional blocks are spatial cells. Depending on the type of application of volumetric blocks and other structural elements of a system of block buildings, there are: 1) a homogeneous block system, in which the entire building is assembled from load-bearing volumetric blocks; 2) a heterogeneous block system, in which the building is assembled from bearing and non-bearing blocks; 3) frame-block systems, in which non-load-bearing volumetric blocks rest on the load-bearing frame of the building; 4) block-panel system, in which buildings are assembled from load-bearing volumetric blocks and large panels of external and internal walls and ceilings; 5) a system of suspended volumetric blocks, in which load-bearing volumetric blocks are hung on the load-bearing parts of the building, which are the cores of rigidity.
General provisions for the design of public buildings (classes of capital, durability, degree of fire resistance, main fire-fighting measures)
Buildings are divided into 3 grades in terms of durability:
1st degree - service life over 100 years;
2nd degree - service life from 50 to 100 years;
3 degree - service life from 20 to 50 years;
Less than 20 years are temporary.
Fire safety of buildings
Building materials and structures, if possible, are divided into:
Combustible (combustible), which ignite under the influence of fire or high temperature and continue to burn after removing the source of fire;
Non-combustible (non-combustible), which, under the influence of fire or high temperature, do not ignite, do not smolder or char;
Hardly combustible, which, under the influence of a fire source or high temperature, are difficult to burn or smolder, but when the fire source is removed, their burning or smoldering ceases. Building structures are also characterized by a fire resistance limit, i.e. resistance to the action of fire in hours until the loss of strength or stability, or until the formation of through cracks, or until the temperature rises to 140 ° C on the surface of the structure from the side opposite to the action of fire. By fire resistance, buildings are divided into 5 degrees. When determining the fire resistance of buildings, the fire resistance of the main materials and structures and the fire hazard of technological processes carried out in the building are taken into account. The first degree includes buildings with the highest fire resistance, and the fifth - the least fire resistant.
66. Volumetric planning solutions for public buildings (main groups of premises, requirements for them, basic volumetric-spatial structure of buildings)
Public buildings have the most diverse space-planning composition, depending mainly on the functional purpose and architectural design. Nevertheless, corridors and halls clearly stand out from the wide range of compositional forms of public buildings. Most of the public buildings are represented by a "mixed group", which has become more widespread in the modern service of the population of cities, workers' settlements and rural settlements. Buildings are being built according to the enfilade scheme, in which the movement of the flow of people is directed from room to room with the arrangement of doors along one axis. This layout is typical for the premises of museums, art galleries, and some types of exhibitions.
All types of public buildings are characterized by the main planning elements: premises of the main functional purpose (in administrative buildings - offices, rooms; in halls - halls, in commercial buildings and public catering buildings - trading and dining rooms, in libraries - reading rooms and book depositories etc.); entrance node - as part of the vestibule, vestibule and wardrobe; vertical transport unit - stairs, elevators; premises for movement and distribution of human flows in corridor buildings - corridors and recreation; in theater halls - foyers and lobbies; sanitary facility - toilets, washbasins, personal hygiene rooms.
The relative position of the main planning elements in accordance with the functional purpose and better organization of human flows indicates the quality of the building layout.
Requirements for the design of multi-storey residential buildings
Buildings have the following basic requirements:
a) the requirement of functional conformity, i.e. the building must correspond to its functional purpose;
b) the requirement of technical compliance, i.e. the building must be strong, stable and durable;
c) the requirement of architectural and artistic expressiveness, i.e. the building should be beautiful in appearance and interior design and have a positive effect on a person;
d) the requirement of economic feasibility, i.e. obtaining as a result of construction the maximum usable area or volume of the building with the minimum cost of funds, labor and time for the construction and operation of the building, but with the mandatory fulfillment of the first three requirements.
The correspondence of a building or room to a particular function is achieved when creating optimal conditions for a person and for performing functional processes in this building or room. The conditions in a building or room are characterized by the following factors: space, state of the air environment, sound mode, light mode, and conditions of visibility and visual perception.
a) the space is characterized by the area and volume of the building and its premises and is provided by the size and shape of the building and its premises in plan and in height.
b) the state of the air environment is characterized by the supply of air, its temperature, humidity and speed of movement and is provided by the structures of external fences and sanitary equipment (heating, mechanical ventilation, air conditioning, etc.).
c) the sound mode is characterized by the conditions of audibility in the room, corresponding to its functional purpose, and is provided by space-planning and structural solutions using sound-absorbing, sound-reflecting and sound-insulating materials and structures.
d) the light regime is characterized by the working conditions of the organs of vision, corresponding to the functional purpose of the room, and is provided by the size of window openings and lanterns for natural lighting, their orientation along the sides of the horizon and using artificial lighting.
e) visibility and visual perception are associated with the need to see flat or volumetric objects in a room and are provided due to the light regime and the relative position of the viewer and the object perceived by him.
2. Types of planning schemes for multi-storey residential buildings
Sectional residential buildings The section in a residential building includes a vertical transport unit (stairs and elevators) and apartments adjacent to it by floor. In middle-rise buildings, from 2 to 4 apartments go to the landing of each floor, and in houses with 6 floors and more - at least 4 apartments, which ensures a more economical use of elevators and garbage chutes. Depending on the location in the house, there are ordinary, end, corner and rotary sections. Ordinary sections are located in the middle of the house, end sections are located at the ends, corner and rotary, in places where buildings turn in the plan. In sections of unlimited orientation, the windows of each apartment face both longitudinal sides of the building. Such sections can be located in any direction in relation to the sides of the horizon, including parallel to latitude, and they are called latitudinal. In sections of limited orientation, the windows of each apartment face one of the longitudinal sides of the building. Such sections can be located only parallel to the meridian and they are called meridian. In sections with a partially limited orientation, one part of the apartments overlooks both longitudinal sides of the building, and the other part of the apartments faces one side. These sections are positioned in relation to the sides of the horizon in such a way that the required insolation of apartments with one-sided windows is provided, since insolation of apartments with two-sided windows is provided in any case. Sectional residential buildings are designed in two or more sections. Ordinary sections are most often rectangular, end sections are rectangular or T-shaped, and rotary ones are L-shaped or other shapes.
Each building or structure inevitably experiences the impact of certain loads. This circumstance forces us, calculators, to analyze the operation of a structure from the position of the most unfavorable combination of them - so that even in the event of its manifestation, the structure remains strong, stable, and enduring.
For a structure, the load is an external factor that transfers it from a state of rest to a stress-strain state. Collecting loads is not the ultimate goal of an engineer - these procedures refer to the first stage of the structural analysis algorithm (discussed in this article).
Classification of loads
First of all, the loads are classified according to the time of impact on the structure:
- constant loads (acting throughout the entire life cycle of the building)
- temporary loads (act from time to time, periodically or one-time)
Segmentation of loads allows you to simulate the work of a structure and perform the corresponding calculations more flexibly, taking into account the probability of occurrence of a particular load and the likelihood of their simultaneous occurrence.
Units and mutual conversions of loads
In the construction industry, concentrated power loads are usually measured in kilonewtons (kN), and moment loads are measured in kNm. Let me remind you that according to the International System of Units (SI), force is measured in Newtons (N), length - in meters (m).
The loads distributed over the volume are measured in kN / m3, over the area - in kN / m2, along the length - in kN / m.
Figure 1. Types of loads:
1 - concentrated forces; 2 - concentrated moment; 3 - load per unit volume;
4 - load distributed over the area; 5 - load distributed along the length
Any concentrated load \ (F \) can be obtained by knowing the volume of the element \ (V \) and the volumetric weight of its material \ (g \):
The load distributed over the area of an element can be obtained through its volumetric weight and thickness \ (t \) (size perpendicular to the plane of the load):
Similarly, the load distributed along the length is obtained by the product of the volumetric weight of the element \ (g \) by the thickness and width of the element (dimensions in directions perpendicular to the load plane):
where \ (A \) is the cross-sectional area of the element, m 2.
Kinematic actions are measured in meters (deflections) or radians (rotation angles). Thermal loads are measured in degrees Celsius (° C) or other units of temperature, although they can be specified in units of length (m) or be dimensionless (thermal expansion).
→ Building structures
Loads and influences on buildings
Buildings as a whole and their individual parts experience various influences from loads (mechanical forces) and influences, for example, from changes in the temperature of the outside and inside air.
Under the influence of these loads and influences, internal forces arise in the materials of buildings' structures, the value of which per unit area (intensity of internal forces) is called stress. Stress is most often measured in kg / cm2.
As a result of stresses in materials and structures, deformations can occur, that is, tension, compression, shear, bending, torsion, or more complex deformations.
Deformations can be elastic, i.e., disappearing after the removal of the impact that caused the deformation, and plastic, i.e. remaining after the removal of the impact.
The load can be concentrated when its pressure area is small compared to the size of the body to which it is applied, and can be taken as a point, for example, the load from a person on the floor.
If the pressure area is relatively large, then the load is called distributed. If the load is evenly distributed over the area, then it is called evenly distributed, for example, the weight of a layer of water on water-filled flat surfaces. The nature of the application of loads can be different, for example, on the wall of the basement of a building from the outside, the soil pressure increases as it deepens and is expressed in the form of a triangle with the base at the level of the basement floor.
Ultimate tensile strength, or tensile strength of a material, is the stress in a material under various types of deformation (tension, compression, torsion, bending), corresponding to the maximum (before the destruction of the sample) value of the load, and is measured by the ratio of the maximum load to the area of the initial section of the sample (i.e. i.e. the cross-section of an undeformed sample), usually in kg / cm2.
The main characteristics of the resistance of materials to force effects are the standard resistance (R "), established on the basis of tests.
Rice. 1. Scheme of distribution of loads in the building
a - plan; b - section
The characteristic resistances can be mainly the ultimate strengths at various deformations or the yield points of materials, which are stresses at various types of deformation, which are characterized by the fact that the residual (plastic) deformation is distributed over the entire working volume of the sample at a constant applied load. The characteristic resistances of various materials and structures are given in SNiP II-A. 10-62.
A possible change in the resistance of materials, products and structures in an unfavorable direction in comparison with the normative ones, caused by the variability of mechanical properties (inhomogeneity of materials), is taken into account by the uniformity coefficients (k), which are given in SNiP II-A 10-62.
The features of the work of materials, structural elements and their connections, foundations, as well as structures and buildings in general, which are not directly reflected in the calculations, are taken into account by the coefficients of working conditions (t) given in SNiP II-A. 10-62.
The resistances of materials taken into account in the calculation are called design resistances ® and are defined as the product of standard resistances (R1 ') by the coefficients of homogeneity (/ g), and, if necessary, by the coefficients of working conditions (t).
The values of the design resistances for determining the calculation conditions, taking into account the corresponding coefficients of working conditions, are established by the norms for the design of building structures and foundations of buildings and structures for various purposes.
The greatest loads and impacts that do not constrain or violate normal operating conditions and, in possible cases, are controlled during operation and at production, are called normative.
The possible deviation of loads in an unfavorable (higher or lower) direction from their standard values due to variability of loads or deviations from the conditions of normal operation is taken into account by the overload coefficients (p), set taking into account the purpose of buildings and structures and their operating conditions.
Various standard loads on floors, loads from technological equipment, bridge cranes, snow and wind loads, as well as overload factors are given in the chapter SNiP II-A. 11-62.
The loads taken into account by the calculation, defined as the product of the standard loads and the corresponding overload factors, are called design loads.
All loads and influences causing forces (stresses) in structures and foundations of structures, taken into account in the design, are divided into permanent and temporary. Permanent loads and impacts that can occur during the construction or operation of structures permanently, for example: the weight of permanent parts of buildings, the weight and pressure of the soil, the prestressing forces, the weight of the wires on the supports of power lines and antenna devices of communication facilities, etc.
Temporary loads are those loads or impacts that may be absent during certain periods of construction and operation of the structure.
Depending on the duration of the action, temporary loads and impacts are divided into:
a) temporary long-term ones, which can be observed during the construction and operation of the structure for a long time, for example: loads in the premises of book depositories and libraries, loads on the floors of warehouses, the weight of stationary equipment, the pressure of liquids and gases in tanks and pipelines, etc.;
b) short-term, which can be observed during the construction and operation of the structure only for a short time, for example: loads from mobile lifting and transport equipment, snow and wind loads, wave and ice pressure, temperature climatic effects, etc.; "
c) special, the occurrence of which is possible in exceptional cases, for example: seismic effects in areas subject to earthquakes, water pressure during catastrophic floods, loads arising from the destruction of a part of a building, etc.
When calculating building structures, not all loads and influences affecting them are taken into account, but only certain combinations of loads and influences (basic, additional, special combinations), which are given in SNiP II-A. 10-62 and II-A. 11-62.
By the nature of the action, the loads are divided into static (changing gradually) and dynamic (shock, rapidly and periodically changing).
Dynamic loads and impacts on building structures are taken into account in accordance with the instructions of regulatory documents for the design and calculation of load-bearing structures subjected to dynamic loads and influences. In the absence of the necessary data for this, the dynamic effect on structures can be taken into account by multiplying the design loads by the dynamic factors.
In order for a building to be technically feasible, it is necessary to know the external influences perceived by the building as a whole and its individual elements (Fig.11.2), which can be divided into two types: power(load) and non-power(environmental influences).
Rice. 11.2.
1 - permanent and temporary vertical force effects; 2 – wind; 3 - special force effects (seismic, etc.); 4 - vibrations; 5 - lateral soil pressure; 6 - ground pressure (rebound); 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)
Power effects include various types of loads:
- constants - from the own weight of the building elements, from the soil pressure on its underground elements;
- long-term temporary - from the mass of stationary equipment, long-term stored cargo, own weight of partitions that can be moved during reconstruction;
- short-term - from the mass of mobile equipment, people, furniture, snow, from the action of the wind on the building;
- special - from seismic impacts, impacts as a result of equipment failure.
Non-force effects include:
- temperature influences affecting the thermal regime of the premises, as well as leading to temperature deformations, which are already force effects;
- the effects of atmospheric and ground moisture, as well as the effects of moisture vapor in the air of the room, causing changes in the properties of the materials from which the building structures are made;
- air movement, causing it to penetrate into the structure and premises, changing their humidity and thermal conditions;
- exposure to direct solar radiation, causing a change in the physical and technical properties of the surface layers of the material of structures, as well as the thermal and light conditions of the premises;
- exposure to aggressive chemical impurities contained in the air, which, when mixed with rain or ground water, form acids that destroy materials (corrosion);
- biological effects caused by microorganisms or insects, leading to the destruction of structures and deterioration of the indoor environment;
- exposure to sound energy (noise) from sources inside and outside the building, disrupting the normal acoustic mode in the room.
In accordance with the listed loads and influences, the following requirements are imposed on buildings and their structures.
- 1. Strength- the ability to perceive loads without destruction.
- 2. Sustainability- the ability of the structure to maintain balance under external and internal loads.
- 3. Rigidity- the ability of structures to carry the load with minimum, predetermined deformation rates.
- 4. Durability- the ability of the building and its structures to perform their functions and maintain their qualities during the maximum service life for which they are designed. The durability depends on the following factors:
- creep of materials, i.e. the process of small continuous deformations occurring in materials under conditions of prolonged exposure to loads;
- frost resistance of materials, i.e. the ability of a wet material to withstand alternating freezing and thawing;
- moisture resistance of materials, i.e. their ability to withstand the destructive action of moisture (softening, swelling, warping, stratification, cracking);
- corrosion resistance, i.e. the ability of materials to resist destruction caused by chemical and electrochemical processes;
- biostability, i.e. the ability of organic materials to resist the destructive action of insects and microorganisms.
Durability is determined by the ultimate service life of the building. On this basis, buildings and structures are divided into four degrees:
- 1st - more than 100 years (main structures, foundations, external walls, etc. are made of materials that are highly resistant to the listed types of influences);
- 2nd - from 50 to 100 years old;
- 3rd - from 20 to 50 years (structures do not have sufficient durability, for example, houses with wooden outer walls);
- 4th - up to 20 years (temporary buildings and structures).
The service life also depends on the conditions in which the building and the structure are located, as well as on the quality of their operation.
The most important requirement for buildings and structures is the requirement fire safety... According to the degree of flammability, building materials are divided into three groups:
- non-combustible(do not burn, smolder or charred under the influence of fire or high temperature);
- hardly combustible(under the influence of fire or high temperature, they hardly ignite, smolder or char, but after removing the source of fire or high temperature, combustion and smoldering cease). They are usually protected from the outside with non-combustible materials;
- combustible(under the influence of open fire or high temperature, they burn, smolder or char and, after removing the source of fire or temperature, continue to burn or smolder).
Fire resistance limit of building structures is determined by the duration (in minutes) of resistance to the action of fire until the loss of strength or stability, or until the formation of through cracks, or until the temperature rises on the surface of the structure from the side opposite to the fire, on average more than 140 ° C.
Buildings or their compartments between fire walls - firewalls (Fig. 11.3), depending on the degree of flammability of their structures, are divided into five degrees of fire resistance. The degree of fire resistance of buildings is determined according to Building Norms and Rules (SNiP) 21-01-97 * "Fire safety of buildings and structures".
Rice. 11.3. Firewalls - firewalls(a) and zones(b):
1 - fire wall; 2 - fireproof floor; 3 - fireproof comb
Buildings with load-bearing and enclosing structures made of stone, concrete, brick with the use of slab or sheet non-combustible materials belong to the 1st degree of fire resistance. In buildings of the II degree of fire resistance, materials are also made of non-combustible materials, but they have a lower fire resistance limit. In buildings of III degree of fire resistance, it is allowed to use combustible materials for partitions and ceilings. In buildings of the IV degree of fire resistance, for all structures, the use of combustible materials with a minimum fire resistance of 15 minutes is allowed, except for the walls of staircases. Temporary buildings are referred to the V degree of fire resistance. The fire resistance limit of their structures is not standardized. In buildings of III, IV and V degrees of fire resistance, it is envisaged to dissect them with firewalls and fire-prevention ceilings into compartments that limit the area of fire propagation.
MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION
FSBEI HPE "BASHKIR STATE UNIVERSITY"
INSTITUTE OF GOVERNANCE AND BUSINESS SECURITY
Department of Economics, Management and Finance
TEST
Subject: Maintenance of buildings and structures
Topic: Types of impact on buildings and structures
Completed by: student of group EUKZO-01-09
Shagimardanova L.M.
Checked by: Fedotov Yu.D.
Introduction
Classification of loads
Combinations of loads
Conclusion
Introduction
When buildings and structures are erected near or close to existing ones, additional deformations of previously built buildings and structures occur.
Experience shows that neglect of the special conditions of such construction can lead to the appearance of cracks in the walls of previously built buildings, distortions of openings and staircases, to a shift of floor slabs, destruction of building structures, i.e. to the disruption of the normal operation of buildings, and sometimes even to accidents.
With the planned new construction on the built-up area, the customer and the general designer, with the involvement of interested organizations operating the surrounding buildings, must resolve the issue of examining these buildings in the zone of influence of new construction.
A nearby building is an existing building located in the zone of influence of the settlement of the foundations of a new building or in the zone of influence of the production of work on the construction of a new building on the deformation of the foundation and structures of an existing one. The zone of influence is determined during the design process.
Classification of loads
Depending on the duration of the load, one should distinguish between permanent and temporary (long-term, short-term, special) loads. Loads arising during the manufacture, storage and transportation of structures, as well as during the construction of structures, should be taken into account in the calculations as short-term loads.
a) the weight of parts of structures, including the weight of load-bearing and enclosing building structures;
b) weight and pressure of soils (embankments, backfill), rock pressure.
The prestressing forces remaining in the structure or foundation should be taken into account in the calculations as forces from permanent loads.
a) the weight of temporary partitions, gravies and footings for equipment;
b) the weight of stationary equipment: machine tools, apparatus, motors, tanks, pipelines with fittings, support parts and insulation, belt conveyors, permanent lifting machines with their ropes and guides, as well as the weight of liquids and solids filling the equipment;
c) pressure of gases, liquids and bulk solids in tanks and pipelines, overpressure and rarefaction of air arising during ventilation of mines;
d) loads on floors from stored materials and racking equipment in warehouses, refrigerators, granaries, book depositories, archives and similar premises;
e) temperature technological influences from stationary equipment;
f) weight of the water layer on water-filled flat surfaces;
g) weight of industrial dust deposits, if its accumulation is not excluded by appropriate measures;
h) loads from people, animals, equipment on the floors of residential, public and agricultural buildings with reduced standard values.
i) vertical loads from bridge and overhead cranes with a reduced standard value, determined by multiplying the full standard value of the vertical load from one crane in each span of the building by a factor: 0.5 - for groups of operating modes of cranes 4K-6K; 0.6 - for the group of operating mode of cranes 7K; 0.7 - for the group of operating mode of cranes 8K. Groups of crane operating modes are accepted in accordance with GOST 25546-82;
j) snow loads with a reduced design value, determined by multiplying the full design value by a factor of 0.5.
k) temperature climatic influences with reduced standard values determined in accordance with the instructions in paragraphs. 8.2-8.6 provided q1 = q2 = q3 = q4 = q5 = 0, DI = DVII = 0;
l) impacts caused by deformations of the base, not accompanied by a radical change in the structure of the soil, as well as thawing of permafrost soils;
m) impacts due to changes in moisture, shrinkage and creep of materials.
In areas with an average January temperature of minus 5 ° C and higher (according to map 5 of Appendix 5 to SNiP 2.01.07-85 *), snow loads with a reduced design value are not established.
a) equipment loads arising in start-up, transient and test modes, as well as during its rearrangement or replacement;
b) the weight of people, repair materials in the areas of equipment maintenance and repair;
c) loads from people, animals, equipment on the floors of residential, public and agricultural buildings with full standard values, except for the loads specified in clause 1.7, a, b, d, e;
d) loads from mobile lifting and transport equipment (forklifts, electric cars, stacker cranes, telphers, as well as from bridge and overhead cranes with a full standard value);
e) snow loads with full design value;
f) temperature climatic influences with full standard value;
g) wind loads;
h) ice loads.
a) seismic effects;
b) explosive effects;
c) loads caused by abrupt disturbances in the technological process, temporary malfunction or equipment breakdown;
d) impacts caused by deformations of the base, accompanied by a radical change in the structure of the soil (when soaking subsidence soils) or its subsidence in areas of mine workings and in karst.
Combinations of loads
The design of structures and foundations for the limiting states of the first and second groups should be performed taking into account unfavorable combinations of loads or the corresponding forces.
These combinations are established from the analysis of real options for the simultaneous action of various loads for the considered stage of the structure or foundation.
Depending on the composition of the loads taken into account, a distinction should be made between:
a) the main combinations of loads, consisting of constant, long-term and short-term,
b) special combinations of loads, consisting of permanent, long-term, short-term and one of the special loads.
Temporary loads with two standard values should be included in combinations as long-term - taking into account a lower standard value, as short-term - taking into account the full standard value.
In special combinations of loads, including explosive effects or loads caused by collision of vehicles with parts of structures, it is allowed not to take into account the short-term loads specified in clause 1.8.
When taking into account combinations that include constant and at least two temporary loads, the calculated values of temporary loads or the corresponding forces should be multiplied by the combination coefficients equal to:
in basic combinations for long-term loads y1 = 0.95; for short-term y2 = 0.9:
in special combinations for continuous loads y1 = 0.95; for short-term y2 = 0.8, except for the cases stipulated in the norms for the design of structures for seismic regions and in other norms for the design of structures and foundations. In this case, a special load should be taken without reduction.
In the main combinations, taking into account three or more short-term loads, their calculated values can be multiplied by the combination coefficient y2, taken for the first (in terms of the degree of influence) short-term load - 1.0, for the second - 0.8, for the rest - 0.6.
When taking into account the combinations of loads for one live load, the following should be taken:
a) a load of a certain kind from one source (pressure or vacuum in the tank, snow, wind, ice loads, temperature climatic influences, load from one forklift, electric car, bridge or overhead crane);
b) load from several sources, if their combined effect is taken into account in the standard and design values of the load (load from equipment, people and stored materials on one or more floors, taking into account the coefficients yA and yn; the load from several bridge or overhead cranes, taking into account the coefficient y ; ice-wind load
Methods for dealing with impacts on buildings and structures
When designing engineering protection against landslide and landslide processes, the expediency of using the following measures and structures aimed at preventing and stabilizing these processes should be considered:
changing the topography of the slope in order to increase its stability;
regulation of surface water runoff with the help of vertical planning of the territory, arrangement of a surface drainage system, prevention of water infiltration into the ground and erosion processes;
artificial lowering of the groundwater level;
agroforestry;
consolidation of soils;
restraining structures;
Retaining structures should be provided to prevent shear, collapse, landslides and landslides when it is impossible or economically inexpedient to change the relief of the slope (slope).
Restraining structures are used of the following types:
supporting walls - to strengthen the overhanging rocky cornices;
buttresses - separate supports cut into stable soil layers to support individual rock massifs;
shingles - massive structures to support unstable slopes;
facing walls - to protect the soil from weathering and crumbling;
seals (filling of voids formed as a result of falls on slopes) - to protect rocky soils from weathering and further destruction;
anchoring - as an independent holding structure (with base plates, beams, etc.) in the form of fastening individual rock blocks to a solid massif on rocky slopes (slopes).
Snow-holding structures should be placed in the avalanche initiation zone in continuous or sectional rows up to the lateral boundaries of the avalanche collection. The upper row of structures should be installed at a distance of no more than 15 m down the slope from the highest position of the avalanche separation line (or from the line of snow-blowing fences or kolktafels). Rows of snow retaining structures should be positioned perpendicular to the direction of the snow cover sliding.
Avalanche-braking structures should be designed to reduce or completely extinguish the avalanche velocity on fan fans in the avalanche deposition zone where the slope is less than 23 °. In some cases, when the protected object is in the zone of avalanche initiation and the avalanche has a short acceleration path, it is possible that the avalanche-stopping structures are located on slopes with a steepness of more than 23 °.
Conclusion
To select the optimal option for engineering protection, technical and technological solutions and measures must be justified and contain estimates of the economic, social and environmental effects when the option is implemented or abandoned.
Variants of technical solutions and measures, their sequence, timing of implementation, as well as maintenance procedures for the created systems and protective complexes are subject to substantiation and assessment.
Calculations associated with the relevant justifications should be based on source materials of the same accuracy, detail and reliability, on a single regulatory framework, the same degree of elaboration of options, an identical range of costs and benefits taken into account. Comparison of options with a difference in the results of their implementation should take into account the costs necessary to bring options to a comparable form.
When determining the economic effect of engineering protection, the amount of damage should include losses from the impact of hazardous geological processes and the cost of compensating for the consequences of these impacts. Losses for individual objects are determined by the cost of fixed assets in average annual terms, and for territories - on the basis of specific losses and the area of the threatened territory, taking into account the duration of the biological recovery period and the period of implementation of engineering protection.
The prevented damage must be summed up for all territories and structures, regardless of the boundaries of the administrative-territorial division.
List of used literature
1.V.P. Ananiev, A.D. Potapov Engineering Geology. M: Higher. Shk. 2010 2.S. B. Ukhov, V.V. Semenov, S.N. Chernyshev Soil mechanics, foundations, foundations. M: Vys. Shk. 2009 r. .IN AND. Temchenko, A. A. Lapidus, O. N. Terentyev Technology of building processes M: Vys. Shk. 2008 r. .IN AND. Telichenko, A.A. Lapidus, O.M. Terentyev, V.V. Sokolovsky Technology of erection of buildings and structures M: Vys. Shk. 2010 r. .SNiP 2.01.15-90 Engineering protection of territories, buildings and structures from hazardous geological cargo.