Bridge damage detection from the equivalent damage load by multitype measurements

Traditional damage identification (DI) approaches are based on the structural modal information, which is unstable and affected by the environment. This study proposes a novel bridge DI algorithm for the elastically supported beams with a constant cross-section. The expression of the equivalent damage load (EDL) is deduced from the force-displacement relationship. The EDL only exists in the damaged areas, and it is a good damage indicator. Then, a principal component analysis-based load estimation method is adopted to estimate the external nodal force and the EDL. To reduce the influence of the measurement noise and errors, this study furtherly proposes a robust EDL-based damage indicator, which is calculated from multitype data. The numerical simulations and in-field experiments have discussed the influence of several factors, including damage scenarios and loading conditions, on the proposed damage indicator. All results have shown that the proposed damage indicator is applicable and useful. The proposed approach can detect the damage in a real-time manner with high computational efficiency, and it is useful for the in-operation bridges.