土-桩-结构相互作用对独塔自锚式悬索桥地震响应的影响

Influence of soil-pile-structure interaction on seismic response on self-anchored suspension bridge with single-tower

为研究土-桩-结构相互作用对独塔自锚式悬索桥动力特性及地震响应的影响规律,利用有限元软件Midas/Civil建立了2个空间有限元成桥状态模型,分别采用J.Penzien集中质量模型模拟的桩土边界和承台底部固结边界,并对结构进行了动力特性分析和不同地震工况下的非线性时程分析.研究结果表明,土-桩-结构相互作用延长了结构自振周期,且对主塔参与的振型影响很大.与基础固结模型相比,考虑土-桩-结构相互作用的结构在地震作用下的内力响应减小20%左右,而桥塔位移响应增大约50%,主梁位移响应增大约3%.因此,此类结构抗震设计时需基于不同控制目标选择不同的基础处理方式.

To study the influences of soil-pile-structure interaction on the dynamic characteristics and seismic response of a serf-anchored suspension bridge with single-tower, two spatial finite element models of this structure were established based on the software Midas/Civil. By using the J. Penzien lumped mass model, one model simulated the soil-pile interaction and the other chose fixed boundary under the pile cap. Then ,the dynamic characteristics analysis and nonlinear time history analysis under seismic motions were investigated. The research results show that the soil-pile-structure interaction ex- tends the natural vibration period and has a great influence on the tower dominant vibration model. Compared with the fixed foundation model, the seismic force responses of the structure with soil-pile- structure interaction decrease more than 20%, while the displacement responses on the tower increase about 50% and those on the girder increase about 3%. Thus, during the aseismic design period of this kind of structures, different boundary models should be chosen for different performance objectives.