Studies Of Pounding On Seismic Responses Of Asymmetric Single Pylon Cable-stayed Bridge And Its Approach Bridge

Under the action of strong earthquakes,the bridge structure is often damaged or collapsed due to the collision of adjacent superstructures.However,the development of the cable-stayed bridge is later in China,the research on the collision of the cable-stayed bridge is relatively small,and most of the research results focus on the collision problem of the long-span twin tower cable-stayed bridge.There are few studies on the collision of the asymmetric single pylon cable-stayed bridge.And with the development of the city,the demand for the asymmetric cable-stayed bridge for the internal traffic of the city is becoming stronger and stronger,and it is urgent to perfect the corresponding research system.In order to study the collision effect between the main bridge and its approach bridge of the asymmetric single pylon cable-stayed bridge,the research are as follows:(1)The research results of bridge collision problem at home and abroad are summarized,then the analysis method of structural collision simulation and the collision model are introduced,and the advantages and disadvantages of each model are compared.(2)Taking the Ju Zi Zhou Bridge in Nanping City as the engineering background,the collision model of the main bridge and its approach bridge of the asymmetric single pylon cable-stayed bridge is established by the finite element software MIDAS/Civil 2012,and the dynamic characteristics are analyzed.The results show that the dynamic characteristics of the main bridge and its approach bridge of the asymmetric single pylon cable-stayed bridge are quite different.Under the action of longitudinal earthquakes,the beam ends are likely to collide.(3)The collision response of the asymmetric single pylon cable-stayed bridge,and the influence of the bridge-span arrangement and the collision model for it has been studied.The results show that the collision has an inhibitory effect on the displacement response and the internal force response of the asymmetric single pylon cable-stayed bridge,and produces a large impact force.The bridge-span arrangement has a significant effect on the response of the asymmetric single pylon cable-stayed bridge,and the collision mode has a significant effect on the beam end impact force response.(4)The influence of each influencing factor on the collision effect is studied.The results show that the initial gap,the contact damping and the cycle ratio of the expansion joints have a significant effect on the collision response of the asymmetric single pylon cable-stayed bridge,and the axial stiffness of the shorter main beam is more suitable as the collision element stiffness.(5)The influence of collision factors on the collision effect in different bridge span arrangement and collision mode is studied.The results show that under the same earthquake,the influence of collision on the displacement response and the internal force response of the approach bridge of the asymmetric single pylon cable-stayed bridge are not enhanced when the initial gap of the expansion joint is smaller;and the bending moment response of the fixed pier bottom of approach bridge is more significant.when the cycle is close to one.Compared with the double abutment collision model,the impact force response is obviously enlarged,and the magnification amplitude decreases with the increase of the initial gap of the expansion joint and the damping of the collision unit,and which increases with the increase of the collision unit stiffness.