大跨度异型钢管混凝土拱桥典型病害分析及支座脱空影响研究

Long-span concrete filled steel tube (CFST) arch bridges often suffer from serious vehicle-induced dynamic responses during service, but the reasons and effects of certain remarkable vehicle-induced dynamic responses are not yet deeply explored. Taking a typical long-span CFST arch bridge as a research object, its typical diseases were investigated. Based on the field testing and theoretical analysis, the typical diseases and the effects of supports void were studied. The field investigation and test results show that the void of main girder supports causes differential settlement on both sides of the expansion joint, and aggravates the vehicle impact on the main girder and suspenders. The impact factors of displacement near the expansion joint and midspan reach 1.52 and 1.15 respectively. The variation rate of stress amplitude in suspenders is between -28.0% and 18.5%.The numerical results show that the vehicle-induced dynamic responses of the steel box girder and suspenders change significantly before and after supports get void. The void of the supports causes obvious along-bridge displacement of the main girder, which may reach the same magnitude as the vertical displacement. The peak value of vehicle-induced acceleration of the steel box girder increases significantly after supports get void, and the impact will be more significant when the supports and steel box girder are still able to collide with each other under vehicle load. The stress amplitude in suspenders changes remarkably after the supports get void, and its effect on short suspenders is more obvious. The void of supports is one of the main reasons for the significant change of vehicle-induced impact responses of the steel box girder, suspenders and other components of this type of bridge.