The Seismic Dynamic Response Charasteristic Study Of Curved Bridge Considering Moving Vehicles

For the unpredictability of earthquake,it is common that running vehicles exist on bridge suffered earthquake.When vehicle is over bridge,the seismic response of vehicle-bridge system shows some difference caused by vehicle-bridge coupling relationship with the seismic response of bridge.Compared with straight bridge,the influence of running vehicle to curved bridge's seismic responses is more complicated for the bending-torsional coupling effect and the spatial dynamic characteristic.In the current seismic design code of highway and urban bridge,there is no relevant provision about whether to consider vehicle in curved bridge seismic design.Therefore,the seismic dynamic response characteristic study of curved bridge considering moving vehicles is necessary to carry out.For seismic design and analysis of this type of bridge,the study has important theoretical significance and practical value.Taking curved bridge as subject,this paper considers influence of the dynamic impact and key parameter of vehicle,conducts a research about seismic dynamic response.The main research results are as follows:Firstly,the vehicle-bridge coupling dynamic equation of curved bridge is constructed based on modal synthesis method,and the corresponding vehicle-bridge dynamic analysis program is wrote based on MATLAB.Taking a high-pier curved continuous truss girder bridge with concrete-filled steel tube as example,the field test results of the bridge is employed,and the analysis program is testified.Using the program,the influence of several parameters to overall impact effect,local impact effect and riding comfort is analyzed.The parameters include vehicle speed,road surface condition,vehicle number and position.The result indicates that the impact effect of this bridge is underestimated by present standard.The difference of local impact factor is relatively large for the different position of components.Furthermore,the riding comfort of this bridge is poor.Secondly,the generation method of artificial seismic wave is provided,the vehicle-seism-bridge interaction dynamic analysis equation is constructed based on modal synthesis method,and corresponding analysis program is wrote.Taking a four span concrete curved continuous box girder bridge as example,the analysis method and program is testified indirectly based on the seismic vibration test result s of the bridge scale model.The result indicates that the vehicle-seism-bridge dynamic analysis method and program have relatively high accuracy and applicability,and could be used in subsequent seismic dynamic response analysis of bridge under vehicle l oading.Thirdly,taking a four span concrete curved continuous box girder bridge as example,the dynamic analysis program is employed,the effects of vehicle loading on seismic dynamic response of bridge under different seismic wave and input angle are studied.The characteristic and rule of influence of vehicle loading to seismic response induced by several key factors(e.g.vehicle weight,speed,peak ground acceleration,site condition and height of pier)are studied.The result indicates that the adverse effect of vehicle loading is necessary to be considered in seismic design for its remarkable influence to seismic response of curved bridge.When the adverse influence of vehicle is considered,the seismic wave should be inputted in the direction of attachment and vertical line of side piers.The influence of vehicle to seismic response of bridge shows increasing trend with enhanced vehicle weight and speed.Furthermore,the influence shows reduction induced by increasing of peak ground acceleration.Under certain site condition,the vehicle loading induces beneficial response to seismic response of bridge.Additionally,the influence of vehicle loading is relatively large,when the distribution of seismic wave frequency is concentrated.And the influence of vehicle loading to seismic response shows no obvious correlation with the change of pier height,the rule is complicated.