Torsion and distortion analysis of thin-walled box girder with cantilever flanges

In order to investigate the influence of cantilever flange on the torsion and distortion of thin-walled box girder, based on the generalized coordinate principle, displacement model and geometric equation were established. Using the mixed variational principle, a new theory was presented to analyze the torsion and distortion of thin-walled girder with open and closed cross-section, which can sufficiently take account of the influence of shear deformation. The distribution and composition of shear flow on the box girder with cantilever flanges were analyzed, and the two calculation methods to derive the shear flow were compared and unified to study the internal force state of cantilever flange and its influence. The results showed that the contribution of cantilever flanges to the torsion and distortion effect was mainly reflected in the proportion of warping moment of inertia. The cantilever flanges caused the significant redistribution of torsion and distortion warping stress of closed cross-section. The cantilever flanges caused the increase of shear deformation effect. This effect increased with the increase of the cantilever flanges. The contribution of cantilever flanges can not be neglected for the common box-girder bridges. ©, 2015, Science Press. All right reserved.