Beam stress is pressure applied to a beam that can cause tension, compression, and buckling. These structural members are designed with some elasticity so they give instead of snapping under strain. In the design and construction of a building, it is important to select beams of adequate strength to avoid compromises to structural integrity. If a beam is not strong enough, it can fail, which could create a weak point in a building. Enough weak points, or a poorly positioned one, could cause the whole structure to fall.
Engineers can use a number of different formulas to calculate beam stress. The characteristics of the beam are an important part of the equation, including the length, height, and profile in cross section. Another consideration is the material. Metal beams are stronger than wooden ones, for example, and some metals are more elastic than others. These traits can all have an impact on the way a beam performs when it is subjected to pressure.
Structures add a loading weight to a beam. Beam stress calculations need to determine what will happen to the beam in the finished structure. Other structural members should take some of the weight, reducing strain on a beam, and the configuration within the building can determine how it performs. Beams are used in floors, roofs, and other components of a structure, and need to be very strong in tall buildings because of the incredible weight of the finished structure.
In addition to dead weight, engineers must think about live weight. This includes the beam stress when a building is full of personnel who may be moving and repositioning heavy items, from elevators to manufacturing equipment. Wind and other pressures from the outside can also contribute to live weight. Beam stress calculations may show that a beam cannot perform under some conditions, in which case it will not be adequate for the building's needs.
For any given beam in a building, an engineer can determine the load that will be placed on it, and whether the beam can withstand it. If an engineering check shows that some beams are not sufficient for the need, the engineer may need to make some design changes. These could range from changing a beam for a stronger structural member that can withstand the load to reconfiguring a space to reduce strain on beams. These changes must be made with care, as they can in turn redistribute weight to other beams and cause a problem somewhere else. Computer-aided design software can help with this task.