结构-地基相互作用的频域计算模型

Computational model for structure-foundation interaction in frequency domain

基于比例边界有限元法(SBFEM)建立了结构-无限地基相互作用分析的频域透射边界,这种透射边界精确满足Sommerfeld辐射条件.该方法的特点是可以根据精度需要从低阶到高阶逐步递推计算无限域刚度矩阵,应用简单且十分方便.针对文献中比较常用的各种无限地基计算模型的适应性进行了一定的研究分析.结合无限地基上重力坝的地震响应,对无限地基迟滞效应的影响进行了对比分析,由对比结果可以看出考虑无限地基影响时的坝体最大拉应力分布比常用的无质量地基模型的计算结果约小15%;考虑迟滞效应时最大应力计算结果比不考虑迟滞效应时的计算结果增加了约25%.

Based on the scaled boundary finite element method（SBFEM）,a transmitting boundary for the structure-unbounded foundation interaction analysis in frequency domain is established.The Sommerfeld radiation condition at infinity is satisfied exactly.It has the advantages that the highorder terms are evaluated recursively for unbounded domain stiffness matrix to match with the requirements of accuracy,so it can be conveniently applied to solving practical engineering problems.Features of several approximate models developed in the literatures are investigated.The dynamic response of gravity dam with unbounded foundation is calculated as an example,the lingering effect of the unbounded foundation on the earthquake response of the dam is analyzed.The experimental results show that the dynamic stress modeled by non-mass foundation overestimates the earthquake response of the dam by 15% and the maximum stress considering the effect of the lingering effect is more than that of no lingering effect by 25%.