Impact in Railway Prestressed Concrete Bridges

Ballasted prestressed concrete single track railway bridges, consisting of several box girders with spans of 25, 50, 75, and 100 ft $(1\mathrm{ft}=0.305m)\text{,}$ were studied. The girder cross sections were designed according to American Railway Engineering Association (AREA) specifications. Two percent of critical damping corresponding to the first mode of vibration was assumed for the bridges. The track irregularities on the approaches and the bridges were generated from power spectral density functions for Federal Railroad administration (FRA) Class 4 track. A freight car model, which included the geometric and suspension nonlinearities of the car, was developed and used in the analysis. Impact percentages in the bridges due to a two‐vehicle, 100‐ton freight car train operating at 20, 40, and 60 mph were calculated. These were compared with the values obtained in an earlier investigation and those specied by the AREA.