Analysis of continuous box girder bridges including the effects of distortion

Torsional warping and distortion of the cross-section are important features of thin-walled beams and must be considered fully in the design of box girder bridges. A method of elastic analysis is developed based on the stiffness approach which includes the effects of warping torsion and distortion in addition to the more familiar actions of bending moment and torsion. The method, which is applicable to straight single cell box girders with at least one axis of symmetry, is demonstrated here in the analysis of three different box girder models for which experimental or analytical results were already available. The method is shown to be easy and economical to use and provides a physical insight into the structural response of thin-walled box girder bridges under general loading conditions.