Study On Seismic Action Of Long-span Steel Truss Arch Bridge

The upper part of the steel truss arch bridge is composed of the steel truss and the lower concrete bridge deck through the hanger link.The steel truss arch bridge is widely used because of the beautiful shape,the rigid flexible and the building effect.However,in recent years,the bridge collapse accidents have occurred,in which the earthquake load effect on the bridge structure has the greatest impact on the safety of the bridge structure.The dynamic response of steel truss arch bridge is of great significance.With the development of economy and technology,the research of steel truss arch bridge is gradually mature.In this paper,the basic structure forms of steel truss arch bridge,the cause and form of damage formation of common bridges and the analysis method of seismic response of the related structures and the nonlinear calculation theory of structure are discussed in this paper.On the basis of practical engineering,the self vibration characteristics and seismic response laws of a long span steel truss arch bridge are studied.The main research contents and conclusions are as follows:1)combined with a practical project,the structure of the long-span steel truss arch bridge is simplified,and the finite element software ANSYS is used to establish the spatial finite element model.2)the long-span steel truss arch bridge.The modal analysis is carried out in the space model,and the vibration frequencies and modes of the structures under three different parameters are compared.The results show that the main structure is the motion of the symmetrical side bend of the main arch,the vertical motion and the torsional motion in the part.The vector span ratio and the width span ratio have great influence on the vibration frequency.The cross section area has little effect on the vibration frequency of the structure.3)the seismic response analysis of the long-span steel truss arch bridge structure is carried out by using the time history analysis method.The influence of different vector span ratio,width span ratio and the section area of the hanger to the structural seismic response is mainly taken into account,and the influence of the parameters on the displacement and internal force at different positions of the structure is compared.The results show that the structural displacement of the three waves is most obvious to the dynamic response of the EL seismic wave.The lateral displacement of the structure decreases with the increase of the vector span ratio,and the internal force increases with the increase of the vector span ratio.The increase of the width span ratio can effectively reduce the displacement and bending moment of the structure in the earthquake process,but will increase the shear and axial force of the structure.The loss of cross section area in the process of bridge operation will increase the displacement and internal force of the structure during the earthquake process,and the shock resistance is extremely unfavorable.