Bridge distributed stiffness identification of continuous beam bridge based on microwave interferometric radar technology and rotation influence line

Abstract

Continuous beam bridges are a widely used and prevalent type of bridge. As material properties degrade over time, the bridge stiffness decreases, leading to a reduction in bearing capacity. Accurate identification of bridge stiffness is crucial for safe operation, but there are few studies on identifying the stiffness of continuous beam bridges. This paper proposes a novel method to identify regional stiffness distribution using microwave interference radar technology and rotation influence lines. Firstly, the regionally distributed multi-point displacement influence lines (DILs) are procured via an innovatively designed lightweight radar device and the multi-point rotation influence lines (RILs) can be subsequently derived through a difference method. Utilizing the derived multi-point RILs, the continuous beam is decoupled into multiple-span simple beams featuring additional moment couples. Then the moment envelope area (MEA) can be computed by integrating the superposition principle and the curvature envelope area (CEA) can be determined using multi-point DILs. Finally, the bridge distributed stiffness can be obtained by combining the MEA and CEA of the monitored area. To verify the validity of the proposed method, a laboratory experiment involving a continuous beam is conducted to identify its’ bridge distributed stiffness (BDS).