Requirements for the technical feasibility of the design solution implies the implementation of its design in full compliance with the laws of structural mechanics, physics and chemistry. To do this, the designer must identify and accurately account for all external influences on the building. External influences on buildings are divided into power and non-power.
To power include the following types of loads and impacts:
Constant loads - from the own weight of the building structure and the pressure of the Foundation soil on its underground part;
Long-term temporary load - from stationary technological equipment, partitions, long-term stored cargo (book storage), the impact of uneven deformation of the soil base, etc.
Short-term loads - from the mass of mobile equipment, people, furniture, snow, wind, etc.
Special effects - from seismic events, explosions, subsidence of loess or thawed, frozen ground base of the building, the impact of deformation of the earth's surface in areas affected by mining, etc.
Non-forceful effects include:
The variables outdoor temperature, causing a linear temperature deformation size changes of the exterior design of the building or thermal forces Under the oppression of the manifestation of temperature deformations of the rigid clamping design;
Atmospheric and soil moisture on the material of construction lead to changes in physical parameters, and sometimes the structure of the materials due to atmospheric corrosion and effects of moisture vapor in the room air onto the material of cladding;
Solar radiation, affecting the light and temperature conditions of the premises and causing changes in physical and technical properties. surface layers of construction.(aging of plastics, melting of bituminous materials)
Infiltration of outside air is not the density of fencing structures affecting their thermal insulation properties. and temperature and humidity conditions of the room.
Chemical aggression of water-soluble impurities in the air cat. in the state dissolved by atmospheric moisture, it causes destruction (chem. aggression) of surface layers of construction materials;
A variety of noises from sources outside and inside buildings that violate the normal acoustic conditions of the premises;
Biological impact - from microorganisms and insects to destroying structures made of organic materials.
At design of designs of buildings their resistance to all listed influences shall be provided. This requirement is provided by strength, stability and rigidity of load-bearing structures, durability and stability of performance of enclosing structures. 1. Strength - the ability to perceive force loads and impacts without destruction.
2. Stability - the ability of the structure to maintain balance under power loads and influences.3. Stiffness - the ability of a structure to perform its static functions with small predetermined values of deformation.4. Durability - the deadline for the preservation of the physical qualities of the building structure during operation.The durability of the structure depends on:
creep-the process of small continuous deformations of the structural material during prolonged loading;
frost resistance-preservation of the required strength by wet materials with repeated alternation of freezing and thawing.
moisture resistance - the ability of materials to withstand moisture without significantly reducing the strength of the investigative stratification, excitation, warping and cracking.
corrosion resistance - the ability of materials to resist destruction caused by chemical, physical or electrochemical processes.
biostability - the ability of organic materials to withstand the destructive effects of mikroorganizmov and insects.
5. Stability of performance, which include: heat, sound insulation and air permeability of the fence-the ability of the structure to maintain a constant level of insulation properties during the design life of the building or structural element. The method of calculating the durability of the structure is not created. Therefore, a conditional assessment of the durability of the maximum service life of the building is applied. On this basis, buildings and structures are divided into 4 degrees:
1. service life of more than 100 years (skyscrapers, the Kremlin)
2. service life from 50 to 100 years
3. service life from 20 to 50 years
4. service life up to 20 years (temporary buildings and structures)
In addition, the classification of building structures is carried out on the principle of fire safety, cat. it is determined by the Flammability of structures and their Flammability.
For Flammability of structures there are materials: non-combustible - non-flammable, do not smolder and do not char under the action of fire or high temperature; difficult to ignite difficult to ignite, smolder and char, but the processes of combustion and decay are terminated with the elimination of fire or high temperatures; flammable - ignite or decay under the action of fire or high temperatures, and these processes do not stop after removal of the sources of fire.
Limits of fire resistance of building structures are determined by the duration (in hours) of tests of structures for fire resistance to the occurrence of one of the following limiting States: collapse, formation of through cracks or holes in the structure, increased temperature.