Early Warning Method for Bearing Displacement of Long-Span Bridges Using a Proposed Time-Varying Temperature–Displacement Model

Bearing displacement is a necessary monitoring index for a long-span bridge because abnormal bearing displacements could result from structural deterioration or damage. Therefore, an early warning method is established for bearing displacement of long-span bridges. In this study, a novel time-varying temperature–displacement nonlinear model, which can eliminate the model error induced by temperature field simplification, is first proposed to accurately estimate bearing displacement. Then, early warning methods for abnormal displacement and out-of-bounds displacement of bearings are established using estimation errors, and different warning levels are delineated depending on combinations of the two types of early warning, followed by an implementation procedure for the early warning method. Finally, the long-term monitoring data of a large-span bridge are utilized to validate the advantage of the proposed time-varying model and the effectiveness of the early warning method. The results show that the modeling and prediction errors of the time-varying model are smaller than that of the linear model. Additionally, attention needs to be paid to the changes in the warning information for bearings with large modeling errors, which will correspond to a relatively high warning level.