Seismic Response Analysis For Long Span Bridge With New Earthquake Protective System

Earthquake is a natural calamity harmful humanity in long time. Bridge engineering is lifeline project. It is full of important meaning to aseismic job in city and country and rebuilding project in the region suffering calamity, so it should take enough reasonable and effective aseismic measures to assure that bridge is safe and is used normally in earthquake. When earthquake occurs, ground movement results in the oscillation of bridge structure, which makes structure's internal force and distortion increase sharply. At the same time, because deficiency exists in structure design and concrete configuration and construction procedure, if earthquake's intensity bridge undergoes is far stronger than anticipated intensity in the design, structure may destroy and may even collapse. So it is very important to pay attention to bridge structure's whole design and choose desirable aseismic architecture. Conventional aseismic design method to structure mainly relays on the improvement of intensity and distortion ability of structural component part to resist the seismic load passively. While main focused problem in aseismic design is how to provide this kind of earthquake-resistance ability for structure. In recent years, with absorbing and adopting the accomplishment in aerial and mechanical fields, the structure protective systems such as lock-up device and fluid viscous damper walk up to engineering practice. Those devices belong to the domain of structure control technology. Based on improved manufacture technology for damper device and enhanced testing and experimental technology and accurate calculation method and developed design criteria, damper device has developed into component part of structure from a kind of additional protective measure and substituted for conventional earthquake-resistance component. In China, one Bridge is national important road construction project. It is situated in the seismic district's border of â…§degree. It is planned to build a 65+5*100+65 meters together 630m prestressed concrete continuous variational box section girder bridge .The middle piers will adopt double thin-wall pier and the side piers will use column-shaped pier. The middle piers are on the multi-pile footing. The sill is of thick sand. The third pier of the middle piers is rigidly framed with girder body. Aimed at this bridge's character, the aseismatic design research is proceeded with new earthquake protective system. The paper consists of five chapters. Chapter one is exordium. Chapter two is introduction of basic theory. Chapter three is to set up the analytical model and finite element expression of lock-up devoice and fluid viscous damper in bridge's seismic analysis and to set up the foundation's big mass calculation model to long-span bridge in seismic response analysis and to derive the analytical model and the finite element equation considering the effect of multi-support excitation and traveling waves in long-span bridge's seismic response. Chapter four is to apply this kind of method concerned above to make seismic response's numerical experiment to the large bridge in Jilin province with new type of earthquake protective system with considering the dynamic time history analysis and the effect of multi-support excitation and traveling wave, it discusses the influence to long span continuous box-girder bridge. Chapter five draws a conclusion about this paper's job and suggests a kind of iterative algorithm to solve about damper's nonlinear numerical calculation in dynamics equation, which puts forward a new outlook for future research. In the paper, it uses ANSYS software to make seismic response's numericalexperiment to the bridge. In the analytical procedure, it concerns large amount problems about math and mechanic. How to reasonably set up long span bridge's aseismic finite element analysis model with lock-up and fluid viscous damper and earthquake excitement's input. How to reasonably choose numerical calculation strategy for showing structure's factual working situation in order to get reliable and accurate imitation data. Above problems are this paper's keystones and difficult points. So the paper does some helpful attempt with the use of relative functions provided by ANSYS. Through seismic response analysis to the bridge with new earthquake protective system, there are the following conclusions. (1) In seismic analysis, set up the finite element model of lock-up and fluid viscous damper, which can successfully take part in structure's dynamic analysis and imitate structure protective system's action under press and make computational process simple. (2) Set up the foundation's big mass analytical model for long-span bridge in seismic response analysis and derives the analytical model and equation considering the effect of multiple support excitation and traveling waves on long-span bridge's seismic response. It uses time history analysis, not only considering the structure's effect of multiple support excitation and seismic traveling waves, but also considering the absolute movement course under interaction of foundation and bridge's stake. Finally, it successfully makes numerical experiment in ANSYS with this method. (3) Discuss expression of long-span bridge with new earthquake protective system considering the effect of multi-supported excitement and traveling wave. Through dynamic analysis under seismic excitement and comparative...