Research On Seismic Response Of Suspension Bridge Which Has Rock Anchor Hangers And Whose Tower Is Omitted Partly Or Wholly In The Valley

Suspension bridge can adapt to the terrain.Tower can be omitted partly or wholly according to terrain of bridge site.Tower’s role is replaced by mountains at this moment.But there is little theoretical research and engineering practice. The length of stiffening girder is less than the span.End hangers near area without hangers are likely to be slack. Stress amplitude of end hangers and end bar can’t be ignored.Supports’tension is also large. Rock anchor hangers which are set reasonably can solve the problem effectively. Valley vibration is quite different from level. This will be reflected in seismic response. Component failure may lead to structural failure in some occasional case.Therefore we should know failure modes and performance of damaged structure.This article focuses on reasonable parameters of rock anchor hangers, valley’s influence on seismic response and suspension bridges seismic response under good condition and damaged state. A dimensional finite element model is built by using BNLAS which is a bridge nonlinear analysis software.The first problem can be got from the calculation results.The relationship between space,initial tension,area of rock anchor hangers and arranged effect is obtained by parameter analysis. Main cable secondary stress which is a reference index also can be known. Then reasonable layout is determined.Based on viscoelastic boundary theory and ANSYS, the contrast between valley vibration and horizontal ground motion is conducted. Valley’s influence on seismic response is obtained when the P wave and SV wave incident vertically.A dimensional finite element model is built by using ANSYS, time history parameters of support points are used for nonlinear time history analysis. Structure response is calculated and compared under the longitudinal, vertical and E1 earthquake. Important coefficient of hangers is calculated based on energy method. Key factor of continuous damage is determined by analyzing single hanger failure.Limited value of hanger failure is obtained under different failure modes. Capacity and seismic response under damaged state are analyzed.Then practical recommendations are made for structural safety.