DESIGN OF TRANSVERSE WEB STIFFENERS IN PLATE AND BOX GIRDER BRIDGES

The behaviour of and design requirements for the transverse stiffeners of transversely stiffened web plates in plate and box girders has been studied using a fully non-linear finite element package. Using nodal line representation of the transverse stiffeners, the form and magnitude of the forces applied to the stiffeners during the collapse of the web plates were investigated. Analyses were also carried out with discrete stiffeners so that the variation in strength with stiffener size could be determined and the effect of the deflection of the stiffener assessed. A limited study was also carried out with a complete girder arrangement including flanges, so that the contribution of the transverse rigidity of the flanges to girder shear strength could be established. Analyses were undertaken for webs in shear, bending and direct compression. Using the results of the finite element study for validation purposes, a simple beam model was formulated with the stiffener and associated width of web plate acting as a beam spanning between the girder flanges, subjected to a lateral load resulting from the destabilising action of the buckling web plates. This simple design model can be used to optimise the stiffener size and is compatible with the basic approach adopted in the British Code BS5400, Part 3, which can therefore be modified to allow for the findings of this study. (A) For the covering abstract see IRRD 864118.