Seismic Response Analysis Of High-pier Long-span Stiffened Steel Truss Continuous Rigid Frame Bridge

The aseismic problem of long-span continuous rigid frame bridge has been concerned by engineering and academic circles.Long span continuous rigid frame bridge is widely used in bridge construction because of its strong spanning capacity,beautiful shape and other advantages.But the long-span bridge is easy to be destroyed and repaired in the earthquake,and it will bring serious secondary disaster and economic loss.Therefore,it is very necessary to study the seismic performance of long-span stiffened steel truss continuous rigid frame bridge under earthquake.In this paper,taking the main bridge(97+2×180 + 97)m stiffening steel truss continuous rigid frame bridge of moguhe 2 super large bridge of Yinxi high-speed railway as the background,the seismic response of the bridge is analyzed,and the following main contents are studied:(1)In order to study the effect of pile-soil interaction on the seismic response of long-span stiffened steel truss continuous rigid frame bridge,in this paper,Midas Civil is used to establish the model B considering pile-soil interaction,and the consolidation model A of bearing platform bottom,and the appropriate seismic wave is selected,time history analysis is used to study the effect of pile-soil interaction on the seismic response of the bridge.The results show that the displacement of main pier increases and the peak value of internal force of main pier decreases to some extent after considering pile-soil action,which shows that considering pile-soil action is beneficial to seismic design of bridge.(2)The seismic response analysis of the bridge under uniform seismic excitation is carried out,the seismic input of three different seismic waves under different working conditions is used to compare the time history analysis results of different seismic waves under different working conditions,and the seismic response of the bridge structure under uniform seismic excitation is obtained.By comparing the two-dimensional and three-dimensional time history analysis of the internal force and displacement response of the bridge pier and the main beam control section,the influence of vertical ground motion on the seismic response of the bridge structure is obtained.The results show that the vertical ground motion has great influence on the axial force,the shear force,the bending moment and the vertical displacement of the main beam.(3)Considering the effect of traveling wave on the bridge,the multi-point excitation under the joint action of two-way orthogonal component and three-way orthogonal component is applied to the bridge by using Fernando wave,and compared with the uniform excitation.The results show that when considering the traveling wave effect,the internal force of the structure is related to the input of the ground motion and its own characteristics,and there are not too many rules,but the traveling wave effect will have a certain impact on the bridge.It is not always safe to only consider the uniform excitation in the seismic responseanalysis.Therefore,the influence of traveling wave effect should be considered in seismic response analysis.(4)Considering the influence of friction action of movable supporting on the seismic response of the bridge,the nonlinear bearing is simulated by using the spring with bilinear restoring force relationship,and the El Centro wave is used for two-way orthogonal union action,and the influence of different friction coefficient on the seismic response.The results show that: in most cases,the friction action of movable supporting can play a role of friction energy dissipation,but considering friction action of movable supporting is not always safe,Therefore,it is necessary to pay attention to the influence of friction action of movable supporting in the seismic response analysis.