Large Span Single Tower Self-anchored Suspension Bridge Seismic Response Analysis And Mitigation And Isolation Measures

With the enhancement in our country of economic strength and the needs of the development of traffic,self-anchored suspension bridge is developing very fast in recent years. But the seismic theory and analysis for this structure is not deep enough and perfect.In order to ensure the safety of the bridges under the earthquakes and extend their service life, the seismic resistance design research for the long-span self-anchored suspension bridge turn into a very necessary and meaningful task.Based on Foshari Pingsheng Bridge, using geometry nonlinear finite element calculation theory and time history method, long-span single tower self-anchored suspension bridge is researched on its seismic response and seismic mitigation and isolation measures. The main work can be described as below:1.Dynamic finite element model of entity bridge and the model with longitudinal minus isolation device for Pingsheng Bridge are established using the MIDAS/Civil, a large general finite element software. Dynamic analysis results indicate that,the joinment of the seismic mitigation and isolation device change the dynamic characteristics of the original floating structure, which greatly improve the longitudinal stiffness of the bridge and make the first longitudinal order mode disappear.2.Seismic response on the original floating structure of Pingsheng Bridge under the longitudinal and vertical seismic waves is analysed in this thesis, using the response spectrum analysis method and time history analysis method, and the result make clear that the longitudinal displacements in girder and towertop are larger, and longitudinal response of the structural system is smaller under the vertical seismic wave.3.Parameters of the viscous dampers are optimized through the orthogonal design method, and seismic mitigation and isolation effect of the viscous dampers is analysised on the basis of parameter optimization. The results make know in the longitudinal earthquake effect, longitudinal displacement in the towertop, tower beam connection and beam end of the structure with viscous dampers are respectively reduced 43.52%, 75.45% and 72.43%.4.Parameters of the lead-rubber-bearings are optimized through the orthogonal design method,and seismic mitigation and isolation effect of the lead-rubber bearings is analysised on the basis of parameter optimization. The results show that in the longitudinal earthquake effect, longitudinal displacement in the towertop, tower beam connection and beam end of the structure with lead-rubber bearings are respectively reduced 35.18%,63.8% and 64.68%.