地震波频率非平稳对土石坝非线性结构响应影响研究

地震动具有频率非平稳性的特征，对结构动力响应存在显著影响。本文发展基于小波包变换的人工地震波随机模拟方法，生成了一系列匹配目标加速度反应谱、能量累积过程和重要持时，同时具有特定频率非平稳性的人工地震波。以美国Success土石坝为例，研究了地震动频率非平稳性对土石坝非线性结构响应的影响。结果表明，控制模拟地震波的频率非平稳性，对土石坝结构响应有着更好的无偏估计，平稳地震波会低估坝体响应。

Effect of frequency-domain nonstationarity of ground-motion on the nonlinear dynamic responses of embankment dams

Ground motion is a complex time series with nonstationarity in frequency-domain which has significant effect on the dynamic response of structures.In this paper,a stochastic simulation method of ground-motion is developed using the wavelet packet transform,and then a series of simulated ground motions that match the target spectral accelerations,but also match Arias intensity (I_a) build-up process,significant durations as well as nonstationarity characteristics are generated.Moreover,the effect of frequency-domain nonstationarity on the nonlinear dynamic responses of an embankment dam are investigated using these synthetic motions.Results show that the ground motions of which the frequency nonstationarity is controlled have a better unbiased estimation of the structural response,and stationary ground motions will underestimate the responses of the dam.