Bracing in completed composite box girder bridges

Abstract

During construction, bracing systems are included in box girders to prevent excessive distortion or twist of the sections. The influence of bracing on the deformation of composite bridges during service is examined. A linear elastic finite strip analysis was developed and results are compared with experimental studies from a model and a prototype bridge. The effectiveness of transverse web stiffeners and distortional bracing in preventing distortional stresses is studied. Transverse web stiffeners are effective in resisting distortion of completed girders, and distortional bracing is not essential for stiffened girders. For unstiffened girders, bracing is essential if additional longitudinal stresses due to distortion are not included in design. Interconnecting bracing between boxes is found to be effective in reducing transverse slab moments. Key words: bridges (box girder), bridges (composite), distortion, load distribution, web stiffening, bracing.