Flexural Behavior and Ultimate Capacity of Adjacent Box Girders with Expansion Joint in the Parapet

Abstract

The incorporation of expansion joints in the parapet wall of bridge girders is standard practice to account for factors such as temperature differentials, shrinkage, and settlement. Gaining an understanding of the influence of expansion joints in bridge parapets is important, since the overall service performance and integrity of the bridge can be significantly influenced by the presence of expansion joints in parapets. This study investigated the flexural behavior of the bridge girder considering the effects of the expansion joint through experimental testing and numerical analyses. Effects of the expansion joint on flexural stresses and on the migration of the neutral axis of the exterior girder were investigated. Both the cracking pattern of the girders subjected to pure flexure and the ultimate flexural capacity were also examined. Compared with the benchmark specimen without the parapet and expansion joint, it was found that the plane cross section assumption cannot be applied to the cross section at the expansion joint. The stress distribution across the section height is nonlinear, with amplified compressive stresses at the top and lower tensile stresses at the bottom than for the benchmark girders. Diagonal cracks occurred and propagated toward the expansion joint at the pure flexure region. Though the flexural capacity of the single girder was slightly increased, the actual load-carrying capacity of the serviced exterior box girder with the expansion joint was substantially decreased.