Condition analysis of expansion joints of a long-span suspension bridge through metamodel-based model updating considering thermal effect

Expansion joints of bridges are vulnerable to damage due to the thermal expansion and contraction, vehicle traffic, and so forth. Currently, the temperature–displacement relationship model may be the only qualitative method for condition evaluation of bridge expansion joints using the field monitoring data. The quantitative assessment based on the finite element model updating techniques is heavy computational burden and time consuming. Therefore, a Gaussian process (GP) metamodel-based model updating method is proposed in this study and performed for the quantitative identification on the boundary condition of the expansion joints of Jiangyin Suspension Bridge using the long-term displacement and temperature monitoring data. At first, the relationship between the longitudinal boundary stiffness (LBS) and structural temperature is formulated on the basis of thermal effects of the bridge deck. The range of LBS is approximately estimated by the regression coefficients from 1-year monitoring data and is used as initial bounds for the subsequent model updating procedure. The GP metamodel is formulated to map the relationship between the LBS and the longitudinal displacements under the thermal effects. The LBS identification of the Jiangyin Suspension Bridge is performed within the fast-running GP metamodel. The results show that the longitudinal displacements using the updated LBS are in good agreement with the measurements, which verifies the effectiveness of GP metamodel-based model updating method in identifying the LBS of the long-span suspension bridge.