Shear Stress Calculation and Distribution in Variable Cross Sections of Box Girders with Corrugated Steel Webs

Based on the condition of static equilibrium and the equivalent law of shearing stress of an infinitesimal segment, this paper provides a strict derivation of the general formula for shearing stress in a nonuniform box girder with corrugated steel webs in the elastic stage. The derived formula is applied to investigate the stress distribution in concrete flanges and corrugated steel webs. Additional shear stress was found to be caused by the bending moment, and the axial force should be included in calculations from the effect of variable cross sections, which are quite different from that of the uniform cross sections. Moreover, because the additional shear stress of the bending moment is self-balanced, the shear force distribution can be adjusted between the concrete slabs and steel webs. Research shows that shear stress decreases markedly in the webs, whereas the shear stress apparently increases in the inclined bottom flange in the action of the bending moment. This study also found and explained the phenomenon that shear stress in the lower surface of the inclined bottom flange is not zero. In the elastic stage, the proposed formula is in good agreement with the results of the three-dimensional (3D) finite-element analysis for a cantilever beam. This example shows that the classic method of material mechanics is no longer suitable for the calculation of a nonuniform beam. Finally, because the formula is too complex to be extensively executed by engineers, two simplified calculation methods are put forward considering the equivalent force principle, and the simplified calculation methods are proved to be valid and applicable according to the contrasting results with the nonuniform mathematical formula. (C) 2016 American Society of Civil Engineers.