【摘要】 为减少直接分析三维大尺度复杂土-结构动力相互作用问题的计算量,提高计算效率,本文直接从波动方程出发,提出了较常规子结构法更简单的两步简化计算过程,即第一步简化上部复杂结构体系为集中质量杆系模型,并求基础处等效输入,第二步通过等效输入求上部结构各位置的动力反应。其中第一步计算主要采用集中质量显式有限单元法结合局部透射人工边界实现,并编写了工程实用性强的时域三维土-结构动力相互作用专用分析程序3DSSI。和其它类似方法相比,本方法的特色从几个方面体现:完全采用时域显式递推的过程,使计算效率较高;上部复杂结构的简化,使计算量仅相当于土体自由场分析;等效输入的获得,可使土体-结构复杂体系的动力分析等效为常规的上部结构动力反应计算;时域算法较常用的频域法在土体非线性方面存在更大潜力。本文还通过典型的三维土-结构模型的建立,与相应的参考解相比,验证了本文提出的计算方法的有效性和计算精度,并初步探讨了土-结构动力相互作用体系的一些基本规律。更多还原

【Abstract】 To save computational efforts,a two-step simplified computational procedure is proposed for three dimensional(3D) dynamic soil-structure interaction(SSI) analysis.In the first step,the whole structure-foundation-soil system under given excitation is analyzed,in which the upper structure is modeled as,for example,lumped-mass beams.In the second step,the response at the structure base obtained from the first step,i.e.the equivalent input,is applied to the base of the upper structure simulated by a sophisticated model,and the required structure responses can be determined.In this paper,an explicit method in the time domain is proposed to simplify the 3D SSI analysis,in which the equivalent input is computed via the lumped-mass explicit finite element method(FEM) with a local transmitting boundary condition.Based on the method,a software package 3D SSI is developed for 3D dynamic SSI analysis.A couple of 3D examples are presented to illustrate the efficiency and reliability of the procedure.The results are in good agreement with the reference solutions.Furthermore,the seismic responses of structures with typical seismic inputs in structure design are studied,and some major characteristics of dynamic SSI systems are investigated.The method can be easily extended to non-linear problems in a straight-forward manner while the method in the frequency domain is impossible.更多还原