Response Analysis Of Horizontal Rotary T-Frame Bridge Under The Motivation Of High-speed Railway Operation

With the continuous improvement of the traffic network,the intersection of lines becomes inevitable.In order to reduce the construction risk when crossing the railway and high-speed railway lines,the horizontal rotation method is widely used.Because of the particularity of the horizontal rotation method,the temporary consolidation at the position of the spherical hinge needs to be removed in the preparation stage of the rotation.At this time,the bridge with the horizontal rotation method can be regarded as an "unstable system".All structural loads above the spherical hinge are transmitted to the cap and foundation only through the rotation spherical hinge.The external interference and the unbalanced moment of the bridge itself are resisted only by the friction moment of the spherical hinge.If the friction moment of the spherical hinge is not enough to resist the unbalanced moment,it will cause the rotation of the spherical hinge,which may be as small as the stuck of the spherical hinge and as large as the overturning of the bridge.Up to now,there are few studies on stress response of spherical joints and internal force response of spherical joints induced by high-speed railway vibration at home and abroad.In view of this situation,this paper mainly carries out the following research work:(1)By arranging vibration test points on the horizontal rotary bridge site,the acceleration time history curves of each measuring point in the site are tested,and the vibration characteristics of each measuring point in the site are analyzed.It is found that the vertical vibration of the ground is more violent than the horizontal vibration and the vertical vibration,and the horizontal vibration and the vertical vibration of the measuring points on the cap are more violent than the vertical vibration.The energy of three-dimensional vibration time history curve of each measuring point is mainly concentrated in the range of 0-70 Hz and100-140 Hz,and the energy of three-dimensional vibration time history curve of each measuring point on the cap is mainly concentrated in the range of 0-70 Hz and 110-125 Hz.(2)Because ABAQUS has powerful non-linear calculation function,the finite element model of the horizontal rotary bridge is established by using ABAQUS to simulate the contact relationship between the upper and lower spherical hinges.The acceleration time history curve measured in situation is applied to the finite element model as an external excitation.The stress variation of spherical hinge steel plate under the vibration is calculated.It is found that the stress of the spherical hinge will change from 0.27 MPa to 22.54 MPa under vibration.The stress of the spherical hinge steel plate after change is still within the allowable range of the strength of the spherical hinge steel plate.Through this study,some suggestions and references can be provided for the following design of spherical hinge of horizontal rotary bridge.(3)In order to reduce the calculation time of the model,the contact between the spherical hinges of the horizontal rotary bridge is simplified.Midas/Civil is used to establish the full bridge model of horizontal rotary bridge,which simplifies the contact of spherical hinges into consolidation state.The acceleration time history curves measured in the field are applied to the finite element model as an external excitation to calculate the overturning moment of spherical hinges under vibration.The safe distance between bridge location and high-speed railway considering only the vibration of high-speed railway is summarized.It can be found that the bridge location can be located only 2 m away from the high-speed railway line considering only the vibration of the high-speed railway operation.At the same time,considering the high-speed railway operation vibration and static wind load combination of Yinghong Bridge,it can be found that for Yinghong Bridge,wind speed less than 15 m/s can be safely switched.