Modified bar simulation method for shear lag analysis of non-prismatic composite box girders with corrugated steel webs

Abstract In this study, a modified bar simulation method is proposed for analyzing the shear lag effect of non-prismatic composite box girders with corrugated steel webs (CBGCSWs) during the elastic stage. In this theoretical method, formulas for the equivalent area of stiffening bar and the shear flow in corrugated steel webs (CSWs) are derived by properly considering the mechanical properties of non-prismatic CBGCSWs. The governing differential equations for shear lag are formulated and solved with given boundary conditions. The feasibility of the proposed method is validated by the finite element (FE) method based on a non-prismatic cantilever beam under different loading conditions. In addition, the shear lag behavior of non-prismatic cantilever CBGCSWs is compared with that of corresponding concrete box girders, and the effects of width-span ratio, girder height ratio, changing curve of girder height and loading form on the shear lag effect of non-prismatic cantilever CBGCSWs are examined based on the modified bar simulation method. Results indicate that non-prismatic cantilever CBGCSWs exhibit more significant shear lag behavior than the corresponding concrete box girders under gravity. The distribution rule of shear flow in concrete flanges, which first increase and then decrease from the cantilever end to the fixed end, causes the transformation between negative and positive shear lag effects in non-prismatic cantilever beams. Increasing the width-span ratio or girder height ratio leads to more serious shear lag effect. The effect of loading form on the shear lag behavior is significant, while the changing curve of girder height has minimal influence.