The bending stresses of steel are calculated using specifications developed by the American Society for Testing and Materials (ASTM). The type of steel used and the structure developed from it alters the allowable stress for steel structures.
Allowable stresses for steel constructions are calculated in knowledgeable strength integrity (KSI) units. Calculations are made to determine the amount of bending stress based on the weight of the construction, joints used and length of steel beams.
An allowable KSI measurement for A36 steel structures with extreme fibres of contact members braced laterally and loaded in plan of minor axis is 24 KSI. Rolled A36 steel braced laterally is allowed a bending stress of 22 KSI based on ASTM specifications.
Steel beams and framing formed as solid round and square bars on solid rectangular steel bars are allowed a stress of 27 KSI.