Study On The Static And Dynamic Properties Of Long-span Road-Rail Suspension Bridge

Suspension bridge is a flexible structure, which has long been plagued by the development of the Road-Rail suspension bridge is the deflection problem rather than the load problem. So it is very necessary to discuss and analyze the rigidity of the Road-Rail suspension bridge. However, no sufficient practice and study as well as corresponding standard for long-span railway bridges were available. In this paper, the problem of the stiffness of the Road-Rail suspension bridge is studied, and the following research work is done.(1) The theory of static calculation and dynamic calculation of suspension bridge is studied, which provides a theoretical basis for the static and dynamic analysis of the suspension bridge.(2) In this paper, a Long-span Railway suspension bridge is used as the engineering background. Finite element software Midas Civil is used to establish the spatial finite element model of the suspension bridge. And the main cable internal force distribution, the internal force of the main beam stress and live load under the action of vertical deflection, vertical angle and lateral wind load under lateral deflection, rotation of the static calculation results are analyzed. The results of the dynamic response of the whole bridge under three directions are calculated, and the dynamic response of the seismic time history response is calculated.(3) The structural parameters are analyzed, such as the supporting system, placement of side span auxiliary bridge pier, span ratio, sag-span ratio, connection of main cables and the girder, sections of girder, depth-span ratio, width-span ratio, length of internode. The structural parameters are divided into two parts, the overall structure parameters and the form of the main beam. By changing the structure parameters, not only the sensitivity of these parameters on vertical and transverse stiffness was analyzed, but also the economy which was influenced by sag to span ratio was taken into consideration. As the result, the effective measures for improving long-span Road-Rail suspension bridge stiffness were summarized.(4) The influence of structural parameters (the supporting system, placement of side span auxiliary bridge pier, span ratio, sag-span ratio, connection of main cables and the girder, sections of girder, depth-span ratio, width-span ratio, length of internode) on the natural vibration characteristics and seismic time history response of suspension bridge is analyzed, and the principle of selecting the structure parameters with good dynamic performance is concluded.Based on the analysis of the key design parameters of long-span Road-Rail suspension bridge, the conclusion of the bridge stiffness and the dynamic response can be referenced for the design of the same type bridge.