The dimensions of the flange and web are what influence how resilient the structural member is to different forces. A building's structure is exposed to several forces that vary in frequency and intensity. The skeletal structure must be resistant to all of them to avoid potentially fatal and costly consequences.
There are five main forces a structural beam must resist:
Bending: Tensile and compressive stress combine to create a bending moment. Failure from bending is caused when the tensile and compressive forces exceed the yield limit of a beam.
Buckling: When a sudden change in shape due to torsional stress causes the beam to deform. This is more common when oriented as a column. Flanges are an important consideration.
Deflection: Deflection is the amount a structural beam will bow or bend when a load is applied to the length of it. The amount of deflection can be minimized by using an adequate thickness of steel for the structural beam.
Tension: Beams are subject to pulling and stretching forces. Choosing the right web thickness can help mitigate the chance of rippling or buckling.
Vibration: The use of compressors, pumps, and engines on-site causes vibration. To counteract this dynamic force, stiffer and higher-mass beams should be used.
The non-uniform cross-section of a structural beam is designed to deflect or bend under excessive load as opposed to buckling.
