Mechanism and Characteristics of Vehicle-Induced Girder-End Displacement for Suspension Bridges: A Case Study

Significant girder-end cumulative displacements (GECDs) of suspension bridges can occur under operational loads, leading to premature wear of restraint devices in bridges such as bearings, expansion joints, and dampers, which are mainly caused by vehicle loads. Therefore, analyzing the mechanisms and response characteristics of vehicle-induced girder-end longitudinal displacement (GELD), as well as the variability of GELD under vehicle loads, is crucial for effective bridge monitoring and maintenance. First, the relationship between vehicle load distribution and GELD under the coupled deformation of the main cable, hangers, and stiffening girder of the suspension bridge was theoretically derived. The generation mechanism of the antisymmetric characteristics and approximate rigid-body motion behavior of the GELD under vehicle loads was revealed. Second, long-term monitoring data over 13 years from an in-service long-span suspension bridge were applied to reveal the time-frequency domain response characteristics of GELD. Additionally, the antisymmetric characteristics and rigid-body motion behavior of vehicle-induced GELD were first verified based on a spatial–temporal correlation analysis of monitoring data, further supporting the theoretical analyses. Finally, the variability in GELD and GECD under vehicle loads was investigated using weigh-in-motion data. This analysis elucidates the dominant role of the proportion of heavy vehicles and their gross vehicle weight on GECD and clarifies the underlying mechanisms of this influence. The conclusions offer valuable insights for the monitoring and maintenance of restraint devices in suspension bridges, helping to prevent premature damage.