Static And Seismic Analysis Of Yunyang Walnut Ditch Bridge

In recent years,large span reinforced concrete arch bridges have been widely applied to the expressway because of their clear mechanical behavior,low cost and high speed of construction.The deck-type reinforced concrete arch bridge has high requirement for the foundation,and they are widely used in the southwest area.As the throat of a road,checking the structure is the premise to ensure its safety operation.Our country is vast in territory,and many areas are near active plates,which is the internal cause of the earthquake.As for the lifeline project of bridge,once it is subjected to earthquake,the bridge can not be used normally or even damaged.It will affect the progress of rescue indirectly and cause incalculable loss of life and property.The non hinged arch can make the line shape of the bridge more smooth,it can adapt to the long-span bridge structure.But the main disadvantage of non hinged arch is that the whole stiffness is large,under the earthquake ductility,arch bridge with concrete as the main bearing member,the tensile strength is very weak,so the long span concrete arch bridge is a bridge of the poor seismic capacity.Therefore,the static calculation of the through concrete arch bridge is first carried out,and then the structural response under earthquake action is analyzed.The above results provide the basis for the establishment of a reasonable and perfect seismic calculation.The research results and the finite element software based on the He Tao ditch double track bridge engineering,the study on large span deck arch bridge static load response and earthquake response values were studied as follows:(1)The arch axis coefficient plays an important role in the stress of the main arch ring.The influence of different coefficients on the axial force,bending moment and shear force of the arch ring is analyzed.The variation law of the stability coefficient of arch bridge with the arch axis coefficient is studied,and the applicable range of the arch axis coefficient is determined according to the stress method.The finite element model of the whole bridge is built by Midas Civil,which verifies that the structural strength,stiffness,stability and bearing capacity of the foundation meet the requirements.The lateral distribution coefficient of hollow slab is calculated by hinged plate method,and the bridge deck is checked.(2)Using the general 3D analysis software Midas Civil,the main arch,bridge column,panel adopts beam element dynamic analysis finite element model is established,using the Ritz method calculation of arch bridges the natural frequencies and corresponding vibration modes,the mode shape can determine the model stiffness and mass distribution is reasonable,summary the seismic calculation method and damping model.(3)On the basis of the bridge site seismic zoning map to determine the peak acceleration response spectrum,choosing smooth curve.Considering along the bridge to the horizontal and vertical seismic input under the main arch vault,four points,internal forces and displacement of the arch at the foot of the response.(4)Using EI-Centro time history wave,considering three directions for time history analysis,the key points are selected according to the result of the response spectrum,the displacement and internal force time history curves are obtained,compared with the response spectrum results.