Dynamic load for girder bridges under normal traffic

Bridge dynamic load is defined as the ratio of dynamic increment to static response. Field measurements are performed to determine the actual truck load effects and to verify the available analytical models presented in other papers. The objective of this paper is to present the results of these studies. The tests are carried out on four steel girder bridges. Measurements are taken using a weigh-in-motion (WIM) system with strain transducers. For each truck passage, the dynamic response is monitored by recording strain data. The truck weight, speed, axle configuration, and lane occupancy are also determined and recorded. A numerical procedure is developed to filter and process collected data. The dynamic load factor (DLF) is determined under normal truck traffic of various load ranges and axle configurations. The field measurements confirmed the results of analytical studies. The stress due to dynamic load is nearly constant and is not dependent on truck weight. Therefore, the dynamic load factor is reduced for heavier trucks.