Normalized shear modulus and material damping ratio relationships
Normalized shear modulus and material damping ratio relationships
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DOI：
10.1061/(asce)1090-0241(2005)131:4(453
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发表时间：
2005-04-01
影响因子：
3.9
通讯作者：
Juang, CH
中科院分区：
文献类型：
--
作者：
Zhang, JF;Andrus, RD;Juang, CH
本文提出了用于估计第四纪、第三纪和更古老的土壤以及残余/腐泥土的归一化剪切模量和材料阻尼比的预测方程。这些方程基于改进的双曲线模型以及对从南卡罗来纳州、北卡罗来纳州和阿拉巴马州获得的 122 个样本的现有共振柱和扭转剪切测试结果的统计分析。归一化剪切模量方程中使用的变量有：剪切应变振幅、围压应力和塑性指数 (PI)。阻尼比的方程用归一化剪切模量加上最小阻尼比的多项式函数表示。研究发现，第四纪土壤比其他两组土壤表现出更多的线性。此外，还发现 PI 对动态土壤行为的影响并不像以前认为的那么显着。来自所有三组的数据都表现出随限制应力的显着变化，类似于 Stokoe 等人确定的变化。使用点估计方法对与 PI 为 0 和平均有效围压为 100 kPa 的方程相关的不确定性进行量化。提供了南卡罗来纳州查尔斯顿的案例研究，以说明方程在地震响应分析中的应用以及考虑围压和地质年龄的重要性。
Predictive equations for estimating normalized shear modulus and material damping ratio of Quaternary, Tertiary and older, and residual/saprolite soils are presented in this paper. The equations are based on a modified hyperbolic model and a statistical analysis of existing Resonant Column and Torsional Shear test results for 122 specimens obtained from South Carolina, North Carolina, and Alabama. Variables used in the equations for normalized shear modulus are: shear-strain amplitude, confining stress, and plasticity index (PI). The equations for damping ratio are expressed in terms of a polynomial function of normalized shear modulus plus a minimum damping ratio. It is found that the Quaternary soils exhibit more linearity than soils of the other two groups. Also, it is found that the effect of PI on dynamic soil behavior is not as significant as previously thought. Data from all three groups exhibit significant variations with confining stress, similar to the variations determined by Stokoe et at. The uncertainties associated with the equations for PI of 0 and mean effective confining stress of 100 kPa are quantified using the point estimate method. A case study from Charleston, S.C. is provided to illustrate an application of the equations to seismic response analysis and the importance of considering confining stress and geologic age.