作　　者： ; ;

机构地区： 广州大学土木工程学院建筑工程系

出　　处： 《防灾减灾工程学报》 2006年第4期369-376,共8页

摘　　要： 在地震动过程中,土介质中的剪切波速往往出现显著的降低现象,体现出强烈的非线性性质。本文将随机振动的虚拟激励原理、土非线性分析的等效线性化方法与工程波动理论散射问题的求解方法相结合,建立了开放系统中一致激励条件下考虑岩土介质非线性的工程场地地震动随机场数值模拟方法。该方法将随机输入下的波动分析问题转换为虚拟激励下的确定性波动分析问题,非线性土体峰值剪应变的统计特征可通过剪应变均方差和峰值因子获得。结合具体算例及M on te—C arlo模拟方法对所提出方法的合理性进行了验证,在此基础上应用该方法对一致激励下实际工程场地的地震动相干性进行分析,结果表明场地的局部条件对地震动相干性有重要影响。 During strong ground motion, the shear wave velocity of soil often decreases greatly which exhibits a great deal of nonlinearity, In this article, with the introduction of the pseudo-excitation method and the equivalent linearization approach into numerical simulation techniques of wave motions considering scattering problem, a nonlinear stochastic wave motion analysis method is presented in which the consistent excitation can be substituted by pseudo--incident waves in terms of the power spectrum density of random excitations, the effective shear strain of nonlinear soil is evaluated by mean peak shear which is computed in terms of its standard deviation and peak factor. The reliability and accuracy of the proposed method is examined through the comparison with results by Monte-Carlo simulation method and is used to estimate the spatial incoherence of earthquake ground motion. The results indicate that the local site conditions have great effects on the seismic ground motion under consistent excitations. The nonlinearity of the soil changes the structure of power spectra of the studied engineering site, this leads to the variation of spectral ratio at observation points and eventually change the spatial incoherence of the site.

关 键 词： 波动有限元分析 虚拟激励法 等效线性化 一致激励 相干函数

领　　域： [建筑科学] [建筑科学]