EFFECT OF TYPICAL DAMAGES ON VEHICLE-INDUCED DYNAMIC RESPONSE OF SIMPLY SUPPORTED MULTI-SLAB GIRDER BRIDGES

摘要

Recently damage identification method based on vehicle-bridge coupled vibrations attracted many researchers' attention.The previous studies focus on the crack damage type,but the other kind of damages happened to actual bridge are rarely mentioned.The research on the effect of typical damages on the vehicle-induced dynamic response of bridges will lay a foundation for the further damage identification research.In the present study,PC simply supported multi-slab girder bridges are studied.Several typical damages frequently occurring on this bridge type,such as hinge joint damage,crack and loss of prestress are considered in this study.Firstly an appropriate numerical simulation method and numerical model for these damages is proposed and verified according to the requirement of dynamic response analysis of bridge under vehicle.Secondly,a suitable multi-slab girder bridge finite element modeling strategy based on multi-scale is developed.A 3D vehicle-bridge dynamic interaction model is used to predict the dynamic response of bridge under vehicles.A field dynamic testing for an actual multi-slab girder bridge under truck is used to validate above analysis model.The displacement and acceleration response of the bridge is recorded under moving truck during in-situ testing.The predicted dynamic response of the bridge is compared with experimental data and the results show good agreement.Thirdly,effect of damages on the dynamic behavior of bridge under vehicles is numerically studied.Various vehicle acting modes and different damage combination cases are considered during the analysis.The distribution characteristics of the most unfavorable and high sensitivity dynamic response of the bridge are presented based on the analysis results.Finally,some suggestions on choosing damage index for damage identification and limiting vehicle acting mode for guaranteeing operation safety of existing damaged bridges are proposed.