Damping formulation for nonlinear 1D site response analyses
Damping formulation for nonlinear 1D site response analyses
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DOI：
10.1016/j.soildyn.2009.01.004
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发表时间：
2009-07
影响因子：
4
通讯作者：
C. Phillips;Y. Hashash
中科院分区：
文献类型：
--
作者：
C. Phillips;Y. Hashash
对大地震期间地面震动的测量和观察表明，场地效应在地震事件期间基础设施的反应中起着主导作用。尽管有大量的努力来模拟土壤的滞回响应和非线性，由于中，大的地面运动，最广泛接受的非线性场地响应方法是不能同时代表的刚度和能量耗散（阻尼）的变化，在实验室测试和地震事件期间观察到的。本文提出了两个新的土壤阻尼公式，实现在非线性一维场地反应分析的小应变和大应变。第一个公式介绍了一种方法来构建一个频率无关的粘性阻尼矩阵，减少了在高频率的过阻尼，因此，在这些频率的过滤。第二个配方引入了一个减少因子，修改扩展Masing加载/卸载应变-应力关系，以匹配测量的模量降低和阻尼曲线，同时在很宽的剪切应变范围。一组的例子来说明使用这两个建议的配方，单独和同时，在非线性场地反应分析的效果。
Measurements and observations of ground shaking during large earthquakes have demonstrated the predominant role of site effects in the response of infrastructure during a seismic event. Despite significant efforts to model the hysteretic response and nonlinearity of soils due to medium and large ground motions, the most widely accepted nonlinear site response methods are not able to represent simultaneously the changes of stiffness and energy dissipation (damping) observed in both laboratory tests and during earthquake events. This paper presents two new soil damping formulations implemented in nonlinear one-dimensional site response analysis for small and large strains. The first formulation introduces an approach to construct a frequency-independent viscous damping matrix which reduces the over-damping at high frequencies, and therefore, the filtering at those frequencies. The second formulation introduces a reduction factor that modifies the extended Masing loading/unloading strain–stress relationship to match measured modulus reduction and damping curves simultaneously over a wide range of shear strains. A set of examples are introduced to illustrate the effect of using the two proposed formulations, separately and simultaneously, in nonlinear site response analyses.