The Study On The Aseismatic Behavior Of A Long-span Continuous Rigid-framed Bridge

In recent years,with the development of bridge structure,the span becomes longer, the height of pier becomes higher and higher,and framework becomes more and more flexible,which presents many new problems in the studies on the aseismatic design of long-span bridge.Long Tan River bridge is situated on the Hu-Rong national highway in the west of Hubei province, and one pier of the bridge is 179m high and has broken the world record.This article makes a series studies on aseismatic behavior by taking this bridge as example,and the major content is as following: At first, the state of the art of aseismatic research of long-span bridge is presented, and based on the stress-strain relationship of combined concrete, the axial force-moment-bending ratio relationship of the pier section is obtained by using the strip method. Then a bilinear skeleton curve model of the combined concrete section is drawn from the relationship curve, additionally, the ductility characteristic of the bridge pier plastic hinge sections is also calculated and studied. Secondly, the seismic wave selection and input are discussed. By using the theory of O.Ramadan, four kinds of man-made seismic displacement wave are produced respectively on consistant excitation,traveling wave,geometric incoherency effect,both traveling wave and geometric incoherency effect. At last, the dynamic equation of multipoint excitated structure is introduced. Thirdly, by using the general-purpose FE software ANSYS, the spatial FE modal is established and the non-linear property of material of plastic hinge section is simulated by using Combin40 element, then how to get the bilinear skeleton curve of moment-twist is derived. Two natural acceleration seismic waves and one man-made consistant excitation seismic displacement wave are input resceptively in the lognitudinal and transverse direction, then the non-linear bending and shearing resistance of the high pier excited by rare earthquake are analysed.At last, four kinds of man-made earthquake waves are input, the internal force in the hige pier is analysed, the influence caused by spatial variation of seismic ground motions is compared, and some useful results are obtained.