Seismic Response Analysis Of Long-span Suspension Bridge

As an important part of lifeline engineering, long-span suspension bridgeplays an important role in ensuring the normal operation of society. While theseismic performance of long-span suspension bridge is influenced by thefrequency characters of seismic excitations due to it’s weak stiffness and longnatural vibration period. Moreover the phase difference of earthquake wavebetween different bears has an important influence on the seismicperformance of long-span suspension bridge too. In addition, the effect ofsoil-structures interaction on bridge is need to be considered. Therefore it haspractical significance to ensure the seismic safety of long-span suspensionbridge by understanding the earthquake damage mechanism deeply andstudying the sismic performance comprehensively of this kind of bridge. Themulti-support excitation seismic response analysis theory and finite elementmodeling methods of long-span suspension bridges are discussed thoroughlyin this thesis. Using numerical simulation method, the dynamic characters andseismic performance of an example long-span suspension bridge with a singlespan dual hinge is studied. The main research work includes:1. The state of the art and the structure characteristics of long-spansuspension bridge are summaried, as well as the development of multipointexcitation research situation of the long-span suspension bridge is introduced.The objective of the study in this thesis is introduced.2. The establishment of the earthquake dynamic equations withmultipoint excitation, and the input method of ground motions are discussedsystematically, as well as the determination method of damping ratio and theissue of geometric nonlinearity of long-span suspension bridges.3. The modeling principle and method of the long-span suspension bridgeare introduced briefly. Based on which the3-D finite element analysis modelof a long-span suspension bridge is built by the MIDAS/Civil program. Thedynamic characteristics of the bridge and the influence of the rigid centralbuckle on the dynamic characteristics are studied.4. The seismic response of the long-span suspension bridge under7kindsof seismic wave and uniform excitation are compared by inputting4earthquake waves with different spectrum characteristics. The influence oftraveling wave effect on long-span suspension bridges are researched detailed.5. The earthquake responses of the long-span suspension bridge under themulti-way input are investigated by inputting3Wenchuan waves, and theeffect of soil-structures interaction on seismic response of long-spansuspension bridge is studied too.