When constructing buildings, it is very important to take into account the degree of influence of external factors on its design. Practice shows that neglecting this factor can lead to cracks, deformations and destruction of building structures. This article will consider a detailed classification of loads on building structures.
General information
All impacts on the structure, regardless of their classification, have two meanings: normative and design. Loads that arise under the weight of the structure itself are called constant, since they continuously affect the building. Temporary are the impacts on the structure of natural conditions (wind, snow, rain, etc.), the weight distributed on the floors of the building from the accumulation of a large number of people, etc. That is, temporary loads are loads on the structure, which during which -any interval can change their values.
Regulatory values of permanent loads from the weight of the structurecalculated on the basis of design measurements and characteristics used in the construction of materials. Design values are determined using standard loads with possible deviations. Deviations may occur as a result of changes in the original dimensions of the structure or a discrepancy between the planned and actual density of materials.
Load classification
In order to calculate the degree of impact on a structure, it is necessary to know its nature. The types of loads are determined according to one main condition - the duration of the impact of the load on structures. Load classification includes:
- permanent;
-
temporary:
- long;
- short-term.
- special.
Each item that includes the classification of structural loads is worth considering separately.
Permanent loads
As mentioned earlier, permanent loads include impacts on a structure that are carried out continuously throughout the entire period of operation of the building. As a rule, they include the weight of the structure itself. For example, for a tape type building foundation, the constant load will be the weight of all its elements, and for a floor truss, the weight of its chords, racks, braces and all connecting elements.
It should be taken into account that for stone and reinforced concrete structures, permanent loads can be more than 50% of the calculated load, and for wooden and metal elements this value is usuallydoes not exceed 10%.
Live loads
Temporary loads are of two types: long-term and short-term. Long-term structural loads include:
- weight of specialized equipment and tools (machines, devices, conveyors, etc.);
- load arising from the erection of temporary partitions;
- weight of other contents located in warehouses, attics, compartments, archives of the building;
- pressure of the contents of the pipelines summed up and located in the building; thermal effects on the structure;
- vertical loads from overhead and overhead cranes; weight of natural precipitation (snow), etc.
Short-term loads include:
- weight of personnel, tools and equipment during the repair and maintenance of the building;
- loads from people and animals on floors in residential premises;
- weight of electric cars, forklifts in industrial warehouses and premises;
- natural loads on the structure (wind, rain, snow, ice).
Special loads
Special loads are short-term. Special loads are referred to a separate classification item, since the probability of their occurrence is negligible. But still they should be taken into account when erecting a building structure. These include:
- load on the building due to natural disasters and emergencies;
- load caused by equipment breakdown or malfunction;
- load onstructure caused by deformation of the soil or the foundation of the structure.
Classification of loads and supports
Support is a structural element that takes on external forces. There are three types of supports in beam systems:
- Hinged fixed support. Fixing the final part of the beam system, in which it can rotate, but cannot move.
- Articulated movable support. This is a device in which the end of the beam can rotate and move horizontally, but the beam remains stationary vertically.
- Rigid termination. This is a rigid fastening of the beam, in which it can neither turn over nor move.
Depending on how the load is distributed on the beam systems, the load classification includes concentrated and distributed loads. If the impact on the support of the beam system falls at one point or on a very small area of \u200b\u200bthe support, then it is called concentrated. The distributed load acts on the support evenly, over its entire area.
