Answer:
B. Based on the allowable shear stress, but the allowable normal stress should always be checked to be sure it is not exceeded
Step-by-step explanation:
Shear stress is analyzed to determine the shear forces along the lenght of the beam. This is represented in a shear force diagram. The beam cross sectional design is determined in such a way as to minimize the shear stress. Allowable normal stress should always be checked in a structure if failure is to be prevented.