Research On Aseismatic Design Of Middle Or Large Span Suspension Bridge

The enormous energy releasing when the earthquake breaks out may cause fatal consequences to the bridge, such as the yielding of pier, the falling beam damage caused by the excessive displacement of bearing, and the collapse of the bridge caused by the damages of the foundation. Because of their incomparable importance, long-span and extra-long-span suspension bridge is many scholars’ favor. They have thorough researches on this kind of bridge, and many conclusions are applied into the engineering practice. By contrast, very few scholars do researches on the seismic response of the middle span and long span suspension bridge, but in reality, the actual number of this kind of bridge is more than the large-span and extra-large-span suspension bridge. Therefore, this thesis mainly researches the seismic response and seismic design of the middle and large span suspension bridge, with an aim to provide helpful reference for suspension bridge seismic fortification to the bridge design and management personnel.In this thesis, the research objective is a representative real middle and large span suspension bridge. This thesis applies the large general Midas/Civ finite element software to establish finite element model, studying the pile-soil interaction’s effects on the dynamic response of the bridge structure, making parameter comparison between the damping coefficient of the viscous damper and the speed index and giving the optimal settings, using the pseudo-static method to analyze and compare the wave passage effect, analyzing the capacity and demand of the different bridge components under different earthquake intensity. The results of this research:(1)The main period of vibration of the middle and long span suspension bridge is very long, and m method is a good way to consider the pile-soil interaction;(2)The seismic reduction effect of the viscous dampers is mainly revealed by the control over the displacement between the main beams and the towers, and the optimal damper parameters is C=3000kN/(s/m)n,the velocity exponent is 0.4;(3) How to calculate the wave-passage effect of ground anchored suspension bridge accurately need more research.If the geological condition of the bridge site is good, the apparent wave velocity is fast,the influence of the wave-passage effect can be neglected,and it is conservative for seismic design.(4)The pillar and the beam of the suspension bridge are the most vulnerable parts in terms of their anti-seismicity, so they need special design.