考虑桩-土相互作用的高墩桥梁抗震性能

Seismic Performance of Tall Pier Bridges Considering Soil-Structure-Interactions

摘要:

采用非线性p-y弹簧模型模拟土体与桩基的相互作用，并通过有限元建模研究了土层对基岩地震动的滤波效应及土体非线性对高墩桥梁地震响应的影响。分析结果表明，若采用合适的地震动输入，在地震动强度较小时，线弹性6弹簧模型能够对高墩的剪力及弯矩响应进行较为精确的估计；但在强震作用下，则会显著高估墩身剪力需求。并且不论采用何种地震输入，6弹簧模型都会极大地低估承台位移响应，对桩基础损伤状态得到偏于不安全的估计。

关键词:桩土相互作用;非线性p-y弹簧;高墩桥梁;抗震性能

Abstract:

This paper investigated the effects of soil layers on the ground motions and seismic performance of tall pier bridges， using finite element models incorporating nonlinear p-y springs. The results show that when proper motions are selected as inputs， the seismic shear force and bending moment of tall piers could be evaluated by linear-elastic six-spring models with acceptable accuracy under earthquake records with a comparatively low intensity. However， when large input intensities are considered， this type of models will overestimate the shear force demands. Furthermore， the displacement demands of pile cap， which serves as an indicator of concrete piles， are always significantly underestimated by the six-spring models， leading to unconservative design for pile foundations.

Key words:soil-structure-interaction;nonlinear p-y springs;tall pier bridges;seismic performance