The Allowable Stress, Load Factor, and Load and Resistance Factor Evaluation of the Historical Swing Steel Truss Riverside-Delanco Bridge

The 2007 collapse of the I-35 West Mississippi River Bridge in Minneapolis has raised questions as to the integrity of steel truss bridges throughout the United States, causing owners to become more concerned about the safety and performance of these bridges. The capacity of the Riverside-Delanco steel truss Bridge (Bridge) was evaluated due to this heightened concern. This historical bridge consists of three pony truss spans, including two simple approach spans and a unique center bearing swing span. These bridge spans were analyzed for their structural integrity. The objective of this evaluation project was to provide the Bridge owner with a comprehensive load rating of the Bridge. The Bridge load rating analyses included allowable stress rating (ASR), load factor rating (LFR), and load and resistance factor rating (LRFR) methods. In addition, a baseline 3D finite element (FE) model of the Bridge, which realistically mimics the behavior of the Bridge, was constructed to help understand the response of the Bridge under various loading conditions. This FE model was utilized in the bridge load rating development and the gusset plate assessment procedures.