Research On The Seismic Behavior Of Long-span Suspension Bridge Under The Far-field Ground Motion

With the development of economy, long-span suspension bridges are more and more widely constructed. In the meantime, the vibration hazard of long-span suspension caused by remote-ground vibration arouses everyone’s attention. Long-span suspension bridges have the characteristics of long period flexible structure, which is more sensitive to longperiod components of earthquake, thus easily affected by remote-ground vibration. Due to the factors mentioned above, the research of seismic resistance of long-span suspension bridges under the circumstance of far-ground vibration is of great significance. The main research contents of this paper are as follows.First, several commonly used methods of bridge seismic analysis and the basic force characteristics of the suspension bridge are introduced. After taking all factors of the effects of the stiffening girder and cable in the process of bridge vibration into consideration, the formula of dynamic response of suspension bridge under earthquake action is derived. Based on the comparison of duration traces and the Fourier spectrum of remote-ground vibration and ordinary-ground vibration, the characteristics of remoteground vibration are summarized. Also, the seismic response of long period structure is briefly explained.Second, the reasonable finite element model of the suspension bridge is established, on the base of which model analysis and the long period characteristics are verified. Seismic waves respectively chosen from remote-ground vibration and ordinary-ground vibration are input in order to get acceleration time history analysis. Dynamic response characteristics of long-span suspension bridges under remote-ground vibration are summarized after comparing the internal force response and displacement response of suspension bridges.Last, this paper introduces the commonly used controlling and vibration-absorbing measures. On the base of remote-ground vibration response analysis, the vibrationabsorbing effect of long-span suspension are researched by setting viscous dampers and elastic connecting devices.