Seismic Response Analysis Of Long-span Steel Arch Urban Bridge

With the arch bridge construction technology matures and the rapid development of iron and steel smelting technology, our country’s construction of steel arch bridge both in span length and in quantity is in the leap type development since twenty-first century. Steel arch bridge has not only high bearing capacity, at the same time, due to the strength of the high ratio, thus it can be designed into a large span Bridges. Currently steel arch bridge is widely used in the railway bridges, highway bridges and municipal bridges because of its graceful structure form etc.In this paper, studying the seismic response through establishing the whole bridge model by finite element software MIDAS/CIVIL based on a concrete-filled steel arch bridge as the engineering background in lanzhou city. The main research contents have the following several aspects:(1) Firstly introducing the current development of steel arch bridge at home and abroad, seismic research present situation and earthquake characteristics. Secondly according to the current development situation of bridge seismic design, introduce the basic methods of bridge seismic analysis, provides a certain theoretical basis for the seismic response analysis of city’s long-span steel arch bridge.(2)According to the theory of structural dynamics, researching the natural vibration characteristics of the bridge through establishing the whole bridge model by finite element software MIDAS/CIVIL. To study the effect of the change of the main arch camber angle on the bridge dynamic characteristics by considering the interaction of piles and soil as well as the change of the main arch camber angle in the analysis process.(3) Through a review of the bridge report to determine the response spectrum curve, using the response spectrum analysis method to run the seismic calculation on the basis of analyzing the dynamic characteristics. Under the effect of E1 ground motion, considering the main arch angle change and bridge in longitudinal seismic effect, lateral seismic effect, longitudinal+ vertical, lateral+ vertical four different input methods seismic response analysis to explore different ways of earthquake ground motion input and arch rib angle response spectrum for large span steel arch bridge have influence on the result of the analysis.( 4) By using nonlinear dynamic time-history analysis, it was conducted that comparisons of the results of analysis of longitudinal and lateral under the uniform seismic excitation through inputing three strong earthquake acceleration records, to explore different ways of earthquake ground motion input on the result of the analysis under the severe earthquake.Based on the relevant mechanical model of friction pendulum bearings(FPB) and calculation parameters, using dynamic time-history analysis study the friction pendulum bearing model, to explore the effect of vibration isolation of FPB pedestal.Through the analysis and study of the above problems, the dynamic characteristics of the steel arch bridge, the most unfavorable combination of seismic wave input of the bridge and vibration isolation performance of friction pendulum bearings have a more profound understanding, and put forward rationalization design suggestions for similar bridge seismic vulnerability.