Effect of Pier Section Reinforcement on Inelastic Behavior of Steel I-Girder Bridges

Abstract

This paper presents the results of an analytical study on inelastic behavior of a four-span continuous composite bridge girder. The objective is to evaluate the effect of pier section reinforcement on strength and ductility of the girder. The reinforcement consists of two pairs of longitudinal ribs bolted to the web of steel sections adjacent to interior piers. Nonlinear finite element analyses are carried out to determine the moment-curvature characteristic of the pier sections. The results indicate that unreinforced sections fail due to local buckling upon yielding of the compression flange whereas the reinforced sections reach their plastic moment capacity with good ductility. Idealized moment-curvature curves are developed based on the nonlinear analyses of the sections. The idealized curves are then used to evaluate the behavior of the girder. The results indicate that strength and ductility of the girder improves substantially when the pier sections are reinforced. At failure, the maximum vertical deflection of the reinforced girder is about twice the deflection of the unreinforced girder. The ultimate load carrying capacity of the reinforced girder is also significantly larger than that of the unreinforced girder.