Study on Damage Detection Method Based on Dynamic Displacement at Bridge–Vehicle Contact Point

To further enhance the convenience, economic efficiency, and safety of damage detection for small- and medium-span bridges, this article presents a damage identification method founded on the bridge deflection at the vehicle position. This method is developed through theoretical derivations, numerical simulations, and laboratory validation using scaled samples, and it offers potential applications for bridge structures. The sum of the fourth-order coefficients of the bridge deflection at the vehicle position is employed as the damage identification index. Theoretical derivation indicates that this index can locate the damage position and quantitatively describe the damage degree without relying on undamaged bridge information. Each damaged part is independent of the others and is not influenced by undamaged parts. Through numerical simulation of the vehicle–bridge interaction system, the effectiveness of this index in identifying single or multiple bridge damage points on the beam is analyzed. The impacts of factors such as damage degrees, measurement noise, and road surface roughness on the recognition effect are also examined. Using high-precision laser displacement sensors, a dual-track synchronous model test is conducted. A “secondary difference” method is proposed to process the test data, which once again verifies the effectiveness of the method. It is pointed out that reducing the vehicle speed and increasing the vehicle weight can improve the accuracy of damage identification. The research presented in this article is founded on theoretical derivations, numerical simulations, and laboratory validation with scaled samples.