Study On The Fatigue Of Steel Box-concrete Composite Girder Bridge With Corrugated Webs Based On Fine Analysis Of Vehicle-bridge Coupled Vibration

For the study of steel box-concrete composite girder bridge with corrugated steel webs fatigue performance,with Jingzhong high-speed airport in lanzhou city,Gansu province connecting a steel box-concrete composite girder bridge with corrugated steel webs as the research object,based on the vehicle-bridge coupled vibration numerical model,research under vehicle load steel box-concrete composite girder bridge with corrugated steel webs fatigue dynamic impact factor,the main research content is as follows:(1)According to the basic theory of vehicle-bridge coupled vibration and on the basis of vehicle model,bridge model and roughness of road surface,the finite element model of bridge was updated by response surface method and Fmincon algorithm.The fatigue stress was modified based on the precise displacement mode of the target element.Based on vehicle traffic data in China,a deterioration model of road roughness considering vehicle load was built,and a vehicle-bridge coupled vibration system based on fine analysis was established,which provided numerical simulation conditions for subsequent vehicle-bridge coupled dynamic response analysis.(2)Based on the vehicle-bridge coupled vibration numerical model,the stress and stress range impact factor of steel box-concrete composite girder bridge with corrugated steel webs were studied.Firstly,the key components of the steel box-concrete composite girder bridge with corrugated steel webs which are prone to fatigue failure were studied by using the finite element model.Then,based on the vehicle-bridge coupled numerical model,the stress and stress range impact factor of the key components under different levels of road roughness and different vehicle speeds were analyzed.Finally,according to the road roughness degradation model,the maximum fatigue impact factor and the proportion of the road roughness degradation time in the whole life cycle were calculated by weighting,and the design value of the fatigue impact factor of the steel box-concrete composite girder bridge with corrugated steel webs based on the road roughness degradation was proposed.(3)Based on the vehicle-bridge coupled vibration numerical model,the fatigue impact factor of key components near the expansion joint of the steel box-concrete composite girder bridge with corrugated steel webs were studied.First of all,three expansion joint models with different degrees of deterioration were established.Then,based on the vehicle-bridge coupled vibration program,the stress and stress range impact factor variation rules of the key components with different vehicle speeds,different road roughness levels and different degrees of deterioration were analyzed.Then,under the condition of considering expansion joints,the stress range impact factor at the details of key components under different vehicle speeds and different levels of road roughness was calculated.Based on the road roughness deterioration model,the design value of fatigue impact factor considering the deterioration of expansion joints and road roughness was obtained through weighted calculation.Finally,the fatigue impact factor samples were used for envelope fitting formula,and compared with the AASHTO code values.