Modified rotating-angle softened truss model for composite box-girder with corrugated steel webs under pure torsion

Replacement of traditional concrete webs with corrugated steel webs will lead to a significant decrease in torsional stiffness of composite box-girder with corrugated steel webs, which needs special attention in the design of wide and curved composite box-girder with corrugated steel webs. To improve the accuracy of prediction on the entire torsional performance of composite box-girder with corrugated steel webs, a modified rotating-angle softened truss model for torsion is developed in this study. Modified rotating-angle softened truss model for torsion mainly takes into account the new three-stage average stress coefficients, the new two-stage shear strain relationship between corrugated steel web and slabs, and the torsional deformation coordination of whole cross section. To testify the accuracy of modified rotating-angle softened truss model for torsion and to better understand the performance of composite box-girder with corrugated steel webs under pure torsion, two scaled specimens are tested in this article. The torque-twist curves and shear strains calculated by modified rotating-angle softened truss model for torsion reach a good agreement with experimental results, which indicates that modified rotating-angle softened truss model for torsion can successfully predict the entire torsional performance of composite box-girder with corrugated steel webs. In addition, compared with test data obtained from previous literature, the proposed modified rotating-angle softened truss model for torsion is more capable of predicting full torsional response of composite box-girder with corrugated steel webs than other rotating-angle models, especially at cracking stage and ultimate stage.