Calculation of Shear Stress in New-Type Composite Box Girder with Corrugated Steel Webs under Restrained Torsion

The objective of this paper is to outline a method for the systematic analysis and calculation of the constrained torsional shear stress in corrugated steel web composite box girders. Initially, leveraging Umansky’s secondary theory, the calculation formula for the constrained torsional shear stress within the composite girder is derived from the conditions of cross-sectional torque equilibrium and continuity in warping displacement. Subsequently, a torsion test is conducted using a scaled model of an actual girder. Finally, the constrained torsional shear stress of the corrugated steel web composite girder is examined based on theoretical analyses and the results of torsion testing. The influence of wing plate length and web thickness on the torsional shear stress of the composite girder is also investigated. The findings reveal a strong agreement between the experimental results obtained from model testing and the theoretical calculations. Notably, under torsional constraint, it is observed that the shear stress in the web is maximal and evenly distributed, followed by the bottom plate and then the top plate, with no discernible shear stress observed at the free end of the cantilever plate. Numerical analysis indicates that an increase in the relative width of the cantilever plate initially leads to an increase in shear stress for both the cantilever plate and roof plate, followed by a decrease until reaching a relative width value around 0.6, where the changes tend to stabilize. Moreover, an increase in web thickness results in a monotonic decrease in web shear stress. Additionally, the shear stress of the roof and bottom plate decreases initially before subsequently increasing.