When building a building, it is very important to considerThe 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. In this article, we will consider a detailed classification of loads on building structures.
General information
All effects on the construction, regardless of theirclassification, have two meanings: normative and calculated. The loads that arise under the weight of the structure itself are called constants, since they continuously affect the building. Temporal effects on the design of natural conditions (wind, snow, rain, etc.) are recognized as temporary, the weight distributed over the building's overlap from the accumulation of a large number of people, etc. That is, temporary loads are the loads on the structure, Either the intervals can change their values.
Normative values of constant loads by weightdesigns are calculated based on design measurements and characteristics used in the construction of materials. The calculated values are determined by means of standard loads with possible deviations. Deviations may appear as a result of changes in the original dimensions of the structure or in the case of a discrepancy between the planned and actual material densities.
Classification of loads
In order to calculate the degree of impact onit is necessary to know its nature. Types of loads are determined by one basic condition - the duration of the impact of the load on the structure. The classification of loads includes:
- constant;
- temporary:
- long;
- short-term.
- special.
Each item that includes the classification of structural loads is worth considering separately.
Constant loads
As already mentioned, to constant loadsrefer to the impact on the construction, which is carried out continuously during the entire period of operation of the building. As a rule, they include the weight of the design itself. For example, for the tape type of the base of a building, the weight of all its elements will be a constant load, and for the overlapping farm - the weight of its belts, pillars, braces and all connecting elements.
It should be borne in mind that for stone andreinforced concrete structures, permanent loads can be more than 50% of the calculated load, and for wooden and metal elements this value, usually, does not exceed 10%.
Temporary loads
Temporary loads are of two types: long and short-term. Long-term structural loads include:
- weight of specialized equipment and tools (machine tools, apparatus, conveyors, etc.);
- load that occurs when erecting temporary barriers;
- the weight of other contents in warehouses, attics, compartments of the building's archives;
- the pressure of the contents of pipelines brought in and located in the building; thermal effects on the structure;
- vertical loads from bridge and suspension cranes; weight of natural precipitation (snow), etc.
Short-term loads include:
- weight of personnel, tools and equipment in the repair and maintenance of the building;
- loads from people and animals to the ceiling in living quarters;
- weight of electric cars, loaders in production warehouses and premises;
- natural load on the structure (wind, rain, snow, ice).
Special loads
Special loads are of short duration.In a separate item of classification, special loads are attributed, since the probability of their occurrence is negligible. But still they should be taken into account when constructing a building structure. They include:
- load on the building due to natural disasters and emergency situations;
- load caused by equipment failure or malfunction;
- load on the construction, which are due to deformation of the ground or foundation of the structure.
Classification of loads and supports
The support is an element of a design that perceives external forces. There are three types of supports in girder systems:
- Hinged and fixed support. Fixation of the end part of the beam system, in which it can rotate, but can not move.
- Articulated arm. This is a device in which the end of the beam can be rotated and moved horizontally, but at the same time along the vertical the beam remains stationary.
- Hard embedding. This is a rigid anchoring of the beam, in which it can neither turn over nor move.
Depending on how it is distributedload on beam systems, the classification of loads includes concentrated and distributed loads. If the impact on the support of the beam system occurs in one point or on a very small footprint, it is called concentrated. The distributed load acts on the support evenly, over its entire area.
