台-土相互作用对整体桥抗震性能影响研究

以某整体式桥台桥梁为研究对象,采用Midas/Civil软件建立了其有限元模型,分别分析了两种桥型(桥型一、二分别为考虑与不考虑台-土相互作用的整体桥)在E1和E2横桥向及纵桥向作用下的结构地震响应。结果表明,桥型二自振频率跳跃较大,对结构更不利,而桥型一的各阶自振频率较为接近;在前6阶振型中,桥型一仅出现一次主梁二阶挠曲,而桥型二出现两次,说明地震作用下桥型二的震害更明显。

整体式桥梁动力特性及抗震性能研究

为深入了解整体式桥梁的动力特性和抗震性能,建立台-土有限元模型,并提出合理的台-土相互作用数学模型,然后利用Midas Civil整体模型研究台-土相互作用、桩-土相互作用、桥墩构造等因素对整体式桥梁抗震性能的影响。结果表明:与简支梁相比,同等跨度下整体式桥梁的纵向刚度明显提高,但横向刚度差距不大;台后土的约束刚度大小对桥梁的静动力特性不产生明显影响,整体式桥梁根据我国现有规范计算台后地震力相对保守;改变桩-土约束刚度对整体式桥梁的抗震性能影响不大;提高桥墩的横向刚度,将独柱墩改为双柱墩能大幅提高结构抗震性能。研究结论及台后土压力系数的计算方式,可供整体式桥梁抗震计算提供参考。

Seismic response of a typical fixed platform foundation under earthquake loading

Offshore platforms in seismically active areas should be designed to service severe earthquake excitations with no global structural failure. This paper summarizes the dynamic analysis of a typical fixed platform under the earthquake loading in the seismically active area. The dynamic analysis includes interpretation of dynamic design parameters based on the available site-specific data,together with foundation design recommendations for earthquake loading conditions,which include free-field site response analyses,liquefaction analyses and soil-pile interaction analyses.