Vehicle-bridge Interaction Of Continuous Rigid Frame Composite Box Girder Bridge With Corrugated Steel Webs Under Earthquake

The continuous rigid frame composite box girder bridge with corrugated steel webs with long-span,green,and light-weight characteristics conforms to the green and environmental concepts that possess high competitive and adaptable.China is a large area country where earthquakes occur frequently.The unique lightweight characteristics of the continuous rigid frame composite box girder bridge with corrugated steel webs can reduce the destructive force of earthquakes,greatly.Therefore,the bridges can be widely promoted,further.However,when summarizing the vehicle-bridge interaction problem of composite box girder bridge with corrugated steel webs mainly found these problems.First,existing analysis methods of vehicle-bridge interaction is too complex to achieve the vehicle-bridge interaction easily.Secondly,The research on considering the coupling of vehicle speed and vehicle weight,the coupling of vehicle speed,road irregularity and bridge fundamental frequency of vehicle-bridge interaction dynamic response are rare.Thirdly,Fewer scholar to study the vehicle-bridge interaction of continuous rigid frame composite box girder bridge with corrugated steel webs under earthquake.What’s more,The calculation method and formula for the impact coefficient is not enough accurate.Therefore,this paper study the vehicle-bridge interaction of continuous rigid frame composite box girder bridge with corrugated steel webs.The main works and results involved in this paper are as follows:(1)This paper introduces and verifies a vehicle-bridge coupling vibration analysis method based on ANSYS single environment.Then,taking Xiaoshagou bridge as the research object,the vehicle-bridge interaction response is researched,considering the effect of different vehicle speeds,the coupling of vehicle speed and vehicle weight,the coupling of braking position and braking speed,the coupling of vehicle speed and road irregularity,the coupling of road irregularity,vehicle speed,and bridge fundamental frequency,respectively.The displacement,bending moment and shear force of time-history data of seven control sections of bridge deck and pier are calculated and extracted.Impact coefficient under different working conditions is acquired.The results showed that when considering the influence of road irregularity randomness,using multiple mean is more reasonable.The descending order of influence factor of the impact coefficient in vehicle-bridge coupling vibration is road irregularity,bridge fundamental frequency,vehicle weight,vehicle speed or vehicle braking.For the bridge deck,the range of the maximum impact coefficient is 0.253～1.389,and the displacement impact coefficient is the largest value having the largest probability comparing with bending moment and shear impact coefficient;while,the pier’s range is 0.253～1.758,and the shear impact coefficient is larger than the bending moment impact coefficient,basically.Considering the coupling of road irregularity,vehicle speed,and bridge fundamental frequency,the impact coefficient is roughly 30% to 65%.(2)Taking the Xiaoshagou bridge as the research object,the vehicle-bridge interaction under earthquake response is researched,considering the effect of seismic type,seismic direction,seismic intensity,respectively.The effects of different vehicle speeds,different road roughness levels,and randomness of road roughness on vehicle-bridge coupling vibration under earthquake are studied,and the results from vehicle-bridge interaction and bridge dynamic response under earthquake are compared.The results showed that vehicle speed and road irregularity does an almost negligible response to bridges,the error after ignoring is 5%,approximately.It is recommended studying the highway bridge’s vehicle-bridge interaction under earthquake response can be simplified to the bridge response under earthquake,directly.(3)This paper put forward a weighted impact coefficient calculation method.First,calculate the various impact coefficients of each bridge control section under each working condition according to bridge code.Then,obtain the comprehensive impact coefficients of the bridge deck and pier according to the impact coefficients of each bridge spans.The results of the displacement,bending moment,and shear impact coefficients are used to obtain the weights of impact coefficients of the displacement,bending moment,and shear.Finally,the final bridge deck and pier impact coefficients are obtained based on the weights value and the comprehensive impact coefficient results.(4)This paper presents a calculation formula for the impact coefficient of a continuous rigid frame box girder bridge,and the practical calculation formula are verified by comparing with current bridge code.The results show that the impact coefficient formula proposed in this paper is safer and more reasonable than the current code.