Simplified gusset plate model for failure prediction of truss bridges

The investigation of the 2007 collapse of the I-35 W Bridge in Minneapolis, Minnesota, used very detailed nonlinear finite-element analysis (FEA). On the other hand, the Federal Highway Administration provided simple guidelines for the load rating of gusset plates, but these are unable to account for the actual behavior of the connections. An intermediate approach is presented here in the form of nonlinear semirigid springs. The model is derived from the FEA of a typical joint, verified against a global, detailed FEA of I-35 W and applied to a Howe truss bridge.