The investigation of the 2007 collapse of the I-35 W Bridge in Minnesota, United States, used very detailed nonlinear finite-element (FE) analysis, which is too difficult for routine design. On the other hand, simple guidelines amenable to hand calculations were provided by the Federal Highway Administration for the load rating of gusset plates, but they are unable to account for the actual behavior of the connections in the global bridge analysis. An intermediate approach is presented, whereby a simplified connection in the form of linear or nonlinear spring models is proposed to improve on current design analysis, which typically is linear and assumes rigid connections. The model is derived from the FE analysis of a typical joint and can be placed at many locations, with modifications required by geometry. The model is verified against a two-dimensional global FE analysis of a steel truss bridge that uses detailed connection models.
Journal of Structural Engineering-ASCE
Bridges, connections, finite-element analysis, gusset plate, linear springs, steel truss.