Real-time damage identification of hinge joints in multi-girder bridges using recursive least squares solution of the characteristic equation

Hinge joint damage is commonly observed in assembled multi-girder bridges, which may jeopardize their serviceability, safety, and sustainability. Timely detection of such damage is crucial for bridge management. Existing damage identification methods regarding hinge joints are either inconvenient in calculation or less sensitive to damage, and struggle with real-time monitoring. Therefore, to overcome these defects regarding assembled multi-girder bridges, this study proposes a real-time damage identification method that can directly estimate the stiffness of hinge joints without any complex finite element model. The proposed method is based on the recursive least squares solution of the characteristic equation of multiple beam systems, which is easy to implement and allows real-time evaluation. The effect of hinge joint damage on the dynamic characteristics of the bridge is quantified through numerical simulation, and the accuracy of the proposed method is verified. Finally, the proposed method is validated on an on-site measured bridge. The bridge consists of 16 girders with a length of 20 m. The results demonstrate that the proposed method practically achieves accurate identification of damage in the real bridge, indicating that the proposed method can be applied to the real-time monitoring of actual bridges to locate and assess hinge joint damage.