基于应变区间折减理论的频率相关等效线性化方法

Frequency-dependent equivalent linearization method based on strain interval reduction theory

为了克服传统等效线性化方法高频段响应被低估的问题,基于传统等效线性化分析原理,结合目前各种频率相关的等效线性化理论方法,提出了考虑有效应变区间折减的频率相关等效线性化方法。采用标准化应变谱表征等效应变与频率的关系,引入剪切应变弹性阈值概念,修正标准化应变谱幅值在弹性应变范围内的频段,同时采用Gaussian平滑方法拟合标准化应变谱,建立有效应变区间折减系数的分段函数,并利用竖向台阵的地震动实测记录对本文方法的可靠性和适用性进行考察。各类场地的分析结果表明:本文方法考虑了地震动高频成分所对应的较大剪切模量和较小阻尼比的实际情况,给出了场地地震反应在高频段的优化结果,可为实际工程的抗震设计提供可靠依据。

In order to overcome the problem of underestimating the high-frequency Fourier spectrum amplification ratio obtained by the original equivalent linearization method, a frequency-dependent equivalent linearization method considering the effective strain interval reduction is proposed. Based on the traditional equivalent linearization analysis theory, various frequency-dependent equivalent linear methods are combined. The standardized strain spectrum is utilized to characterize the relationship between the equivalent strain and the frequency. The concept of shear strain elastic threshold is introduced to modify the standardized strain spectrum amplitude at the frequency within the elastic strain range. The standardized strain spectrum is fitted by the Gaussian smoothing method, then the piecewise function for the effective strain interval reduction coefficient is established. The ground motion measurement records at vertical stations are utilized to investigate the reliability and applicability of the proposed method. The analysis results of various sites show that the method fully considers the actual situation of the larger shear modulus and smaller damping ratio. Those factors are corresponding to the high-frequency component of the ground motion. The proposed method gives the optimization results of the site seismic response in the high frequency band and provides a basis for the seismic design of the actual projects.