Nonlinear Seismic Response Analysis Of Long-span Suspension Bridge

As the great development of national economy, the long-span bridge is built more and more. The suspension bridge, which has super long span for its characteristics of cable bearing, is favored in design for the technologic and economic superiority than the others. As a bridge of lifeline engineering, seismic design is an indispensable part in bridge design because of seismic influences on the safety and reliability of the structure. Plentiful studies are reported on the dynamic behaviors and the seismic design methods, and more focuses are on the seismic responses of suspension bridges.The geometrical nonlinearity of the suspension bridge is prominent for its characteristics of cable bearing. In the past, some scholars have studied the effect of the geometrical nonlinearity in seismic analysis of long-span bridge. For inconsistent of their conclusions ,we need to have further research. So in order to make structure performance of long-span suspension bridge better understand, linear and nonlinear seismic response time-history analysis of two long-span suspension bridges was performed under different earthquake waves of the diffetent soil type and different earthquake magnitude. The main research work covers the following aspects:(1) The models of two long-span suspension bridges for seismic analysis are firstly developed using ANSYS.And secongly the dynamic behavior of the bridges were performenced. Finally the characteristic of modal analysis was concluded.(2) Linear and nonlinear seismic response analysis of two long-span suspension bridges was carried out,and the rules of seismic response were obtained. Finally the effect of geometrical nonlinearity was studied by analying of the seismic response parametes.(3) The problem of slacking of cable is studied by the comparison of seismic responses of the suspended system.(4) The comparison of the most displacement of bridge tower and beam indicates long-preiod part of earthquake waves have important influence on seismic response of long-span suspension bridges.(5) According to the present research situation of long-period spectrum and the application instance of current sesimic design code response spectrum, some methods of obtaining long-period spectrum were discussed.