Torsional behavior of super-span composite box girder with corrugated steel webs

Composite box girders with corrugated steel webs (CBGCSWs) offer the advantages of light weight and noncracking webs and therefore tend to develop into super-span bridges. However, the torsional behavior of the composite box girders under eccentric loading is more prominent, due to the smaller torsional stiffness. Studies on the torsional behavior of super-span CBGCSWs are limited. Therefore, three super-span specimens of CBGCSWs with different cross-sectional forms were designed, and both experimental and numerical studies were carried out in this paper. The performance of finite element analysis (FEA) models was verified by comparing the experimental results, which included the torque-twist curves, cracking modes of concrete slabs, and shear strains of concrete slabs and corrugated steel webs (CSWs). A parametric analysis was also conducted, and a method for calculating the torsional bearing capacity of composite box girders was established based on the three probable failure modes of super-span CBGCSWs. Results indicated that the torsional bearing capacity of the high-web and wide-cell specimens was better than that of the standard specimen. Global buckling of the standard and wide-cell specimens occurred at almost all wavelengths, whereas that of the high-web specimen was concentrated in the middle of the span. The failure modes of CBGCSWs were influenced by the concrete strength and reinforcement ratio. The calculation method can effectively predict the failure modes and ultimate torques of CBGCSWs.