考虑土-结构相互作用的黏弹性减震结构失效概率的参数化分析

Parametric study on failure probability of structures with viscoelastic dampers considering SSI effect

基于基础阻抗与黏弹性阻尼器频率相关的动力特性,在频域中建立了考虑土-结构动力相互作用的黏弹性框架减震结构的动力模型,采用随机振动理论对结构体系进行抗震研究。考虑地基-土体运动相互作用对输入地震动的影响,对自由场地功率谱进行修正得到了基础底部水平有效输入功率谱和回转有效输入功率谱。以结构层间位移角作为控制参数,基于首次穿越原则,定义了结构的失效概率。根据工程实例选取了10层及20层典型框架结构体系,数值分析了结构在不同初始附加阻尼比、基础埋深比及土体剪切波速下的随机地震反应及其失效概率。研究表明,随着土体的变软,阻尼器对结构层间位移角的控制效果将有所减弱,对于高宽比较大的20层结构,其控制效果的下降幅度更为明显。对于软土地基上高层建筑的消能减震设计,SSI效应的影响不容忽视。

Based on the dynamic characteristics of the foundation impedance and the frequency of the viscoelastic dampers,the dynamic model of the viscoelastic frame damping structure considering soil-structure interaction(SSI)was established in the frequency domain,and the seismic behavior of the structural system was studied by using random vibration theory.Considering the influence of foundation-soil interaction on the input ground motion,the effective input power spectrum at the bottom of the foundation and the effective input power spectrum at the bottom of the foundation were obtained by modifying the power spectrum of the free site.Based on the principle of the first crossing,the failure probability of the structure was defined by taking the interlayer displacement angle as the control parameter.According to the engineering examples,10-story and 20-story typical frame structure systems were selected,and the random seismic response and failure probability of the structures under different initial additional damping ratios,foundation buried depth ratios and shear wave velocities of the soil were analyzed.The results show that the control effect of the damper on the interlayer displacement angle is weakened with the softening of the soil.For the 20-story structure with large height width ratio,the decrease of the control effect is more obvious.For the energy-dissipated design of high-rise buildings on soft soil foundation,the influence of SSI effect can not be ignored.