Evaluating reserve bridge capacity through destructive testing of a decommissioned bridge

Chajes, Michael J.Jennifer E. Righman McConnellThis thesis provides testing results from a unique full-scale destructive bridge test of a skewed steel plate girder bridge located in Wilmington, Delaware. The goal of the test was to load the structure beyond its elastic limit to observe transverse load redistribution and to examine the reserve capacity of the structure. The bridge is the second in a series of eight bridges to be decommissioned by the owner, the Delaware River Bay and Authority (DRBA) and the second bridge that was tested by the University of Delaware. The bridge studied here was in good condition and was only decommissioned as part of a traffic realignment project. The bridge was loaded using a loading mechanism consisting of a reaction frame comprised of stiffened girders, coil rods embedded in a mass of concrete covered with backfill beneath the bridge, and hydraulic jacks. Numerous strain gauges were used to monitor the response of the bridge during testing. The equivalent of 17 HS-20 vehicles was applied during the testing without any yielding being recorded in the girders. As a result of the limited applied loading (which was governed by the capacity of the coil rods), a detailed finite element model was calibrated using the recorded response of the bridge. The numerical model was used to predict the post elastic response of the bridge, as well as the structure’s ultimate capacity of 30 HS-20 vehicles. The design codes predicted capacity of 12 HS-20 vehicles, which demonstrates the significant reverse capacity of the structure. Other conclusions from this work are that the loading mechanism was an efficient way of loading the bridge and is promising for use during future destructive bridge tests. Ultimate strength predictions from finite element analysis should be used to determine the required capacity of the loading mechanism and design it accordingly in order to ensure that post-elastic response can be captured.University of Delaware, Department of Civil and Environmental EngineeringM.C.E