Load distribution in edge stiffened slab and slab-on-girder bridge decks

Abstract

The results of a study on the effect of edge beam geometry on the static live-load load distribution characteristics of single-span slab and slab-on-girder bridge superstructures are presented. Using a grillage analysis, the influence of various forms of edge stiffening on longitudinal bending moment and vertical deflection at midspan was investigated. Two load cases utilizing the Ontario Highway Bridge Design truck were considered. Of particular interest is the load case of a single vehicle in a travelled lane, as edge beam deflection under this condition is governed by a serviceability limit state design requirement of the Ontario Highway Bridge Design Code.For the bridge geometry and loadings considered, all types of edge stiffening significantly affect edge beam bending moment and deflection at midspan; the effect generally increases as the span decreases. Edge beam bending moment increases as the stiffness of the edge beam is increased. Considering the change in edge beam stiffness, edge beam deflection decreases even though the bending moment carried by the edge beam increases. The results of the grillage analysis agree well with an interpretation of the simplified method of analysis of the Ontario Highway Bridge Design Code. When the deflection criterion is affecting a bridge design, it would be beneficial to account for the edge stiffening. Key words: load distribution, edge stiffening, edge beams, bridge deck analysis, grillage analysis.