Study on shear behavior of composite box girder with corrugated steel webs with variable cross section considering folding effect

In composite box girders with constant cross section corrugated steel webs, the shear stress in the web is typically calculated based on the applied shear force. For composite box girders with corrugated steel webs of variable cross sections, the calculation extends this approach by further incorporating additional shear effects induced by axial force and bending moment. The resulting web shear stress is obtained by superimposing the shear stress components arising from shear force, axial force, and bending moment. However, due to the unique folding effect of the corrugated steel web, its shear stiffness is significantly reduced. This effect also leads to discrepancies in the rotational angles among the top and bottom flanges, the web, and the overall cross section of the composite box girder. Although the traditional shear stress calculation method has clear physical meaning, it fails to accurately capture, through analytical expressions, the reduction in shear stiffness and the rotational angle discrepancies among these structural components. To address this, the present study derives a shear stress calculation equation for composite box girders with corrugated steel webs, accounting for the shear stiffness reduction caused by the folding effect. A rotational angle displacement function is introduced to reflect the angular discrepancies among the top and bottom flanges, the web, and the composite cross section. The web shear stress is then determined by combining the effects of shear stiffness reduction and rotational angle variation. Using the energy variational method, the shear contributions of the flanges and the web are decoupled. The shear force carried by the flanges is further decomposed into contributions from the top and bottom plates based on moment equivalence. In addition, the shear force distribution ratios among the top plate, bottom plate, and web are examined. Finally, a cantilever beam example is presented to validate the proposed equation by comparing it with existing shear stress calculation expressions for corrugated steel webs, thereby evaluating the shear performance of composite box girders.