Field Study of Overload Behavior of an Existing Reinforced Concrete Bridge under Simulated Vehicle Loads

Overload attributable to increased vehicle loads is becoming an increasingly serious issue in highway transportation. Overload results in damages to bridge structures, degradation of their load-carrying capacities, and even collapse of bridges, which may cause loss of lives and properties. Hence, the actual load-carrying capacity of existing bridges with many years of service and obvious damages is becoming an important concern for researchers and engineers. In this paper, field experiments were conducted on a simply supported concrete girder bridge located at Province Road 209 of Hunan Province, China. Test loads were applied to the bridge through a group of hydraulic jacks to simulate the heavy vehicle loads of 196 and 294 kN on single-lane loaded and two-lane loaded cases. The results showed that at the deflection limit, the measured load-carrying capacity of the tested bridge was much higher than the designed value. During experiments, the transverse connection stiffness of the bridge varied insignificantly. Cumulative damage of the structure was observed when the simulated cyclic loads were increased to three times the weight of the 294 kN truck on a two-lane loaded case.