Finite-Element Modeling of Twin Steel Box-Girder Bridges for Redundancy Evaluation

Abstract

A detailed finite-element (FE) modeling procedure is presented for evaluating the redundancy of twin steel box-girder bridges. For this study, it was assumed that the passage of a truck live load triggers the sudden fracture of one girder. Because of the possibility of localized damage in some bridge components, the proposed computational models incorporate material nonlinearity to represent cracking and crushing of concrete and steel yielding. In addition, the proposed FE models are capable of capturing deck haunch separation by adopting a stud connection failure model. This failure mode was first observed during testing of a full-scale bridge that included a girder with a full-depth fracture. Analysis results show that typical twin steel box-girder bridges likely have greater redundancy than the current provisions indicate and that stud connection failure could significantly affect the redundancy of steel box-girder bridges.