Impact in a railway truss bridge

The aim was to investigate the dynamic interactions between an open deck steel truss bridge and a moving freight train. A non-linear, 100-ton (gross weight 131.5 tons), freight car vehicle model and the 200-ft, open deck, Warren-type steel bridge model were used in this study. Equations of motion for the vehicle, bridge, and bridge/vehicle interactions were also presented. The track irregularities on the approach and the bridge were generated from power spectral density functions for Federal Railroad Administration (FRA) class 4 track (maximum speed 60 mph). Both zero and two percent of the critical damping were assumed for the bridge. Impact percentages in the bridge due to a three, 100-ton freight car train operating at 20, 40, and 60 mph were calculated. These were compared with the data obtained from an earlier field investigation and those specified by the American Railway Engineering Association (AREA) specifications.