Study On Seismic Performance Of H-Single Tower Double Cable Plane Long-Span Cable-Stayed Bridge

Cable-stayed bridges are widely used in the construction of long-span bridges because of their reasonable forces,beautiful shapes,and strong spanning capabilities.China is located between the Asia-Europe plate and the Pacific plate.The crustal movement is relatively active.a large number of bridges have been damaged in varying degrees due to the strong earthquakes in recent years.With the increasing number of cable-stayed bridges in the quake zone,the threat of strong earthquakes also increases.Therefore,it is of great significance to study the seismic performance and seismic isolation of cable-stayed bridges.At present,a lot of researches on earthquake resistance of cable-stayed bridges at home and abroad have been carried out,but most of the related researches focus on double-tower or multi-tower cable-stayed bridges,and there is few study on seismic resistance of single-tower cable-stayed bridges.There have been few studies on the optimization of the viscous damper parameters of single-stayed cable-stayed bridges,and there has been no study on the most unfavorable anchor cables and the most unfavorable cables under strong earthquakes.Therefore,in this paper,it is necessary to carry out research on seismic performance check of single-tower cable-stayed bridges,optimization of viscous damper parameters,and seismic response of stayed cables.In this paper,a H-type single-tower double-cable long-span cable-stayed bridge is used as the engineering background.MIDAS CIVIL software is used to consider the interaction between piles and soil and the cable sag effect.The research also use non-linear time history analysis.The main research contents are as follows:(1)The research status of cable-stayed bridges is analyzed,and the definition,characteristics and mechanism of near-fault ground motion are introduced.(2)The dynamic characteristics of the full-bridge finite element model were analyzed.Three safety-relevant seismic waves at the E1 and E2 levels were input in the two directions of the transverse bridge direction and the forward bridge direction.The seismic response analysis and seismic check calculation of the key section of the cable-stayed bridge were found.Seismic and vulnerable parts of long-span cable-stayed bridges with single towers were identified.(3)Using the bottom moment,the relative displacement of the tower beam and the economic cost as the control indicators,the parameter optimization analysis of the viscous damper of the long-span single-stayed cable-stayed bridge in the background engineering was performed;The principle of elasticity suggests the parameter values of the viscous damper of this bridge;after optimization,the maximum relative displacement of the tower and beam under the original design parameters was reduced by 34%,and the maximum bending moment at the bottom of the tower was reduced by 11.5%.(4)The seismic response of the cable stayed bridge under the E2 earthquake was studied in accordance with the ground motion input along the transverse and transverse directions.The most unfavorable cable-girder anchorage and the most unfavorable cable position were found.The effects of viscous dampers on the seismic response of cables were studied.(5)The influence of viscous dampers on the seismic response of cable under near-fault ground motion was analyzed.