长周期地震动频谱特征周期研究

Study on spectrum characteristic period of long-period ground motions

长周期地震动的频谱特性是影响长周期结构动力响应的重要因素,目前关于其频谱特征周期参数的研究尚有欠缺。根据长周期地震动的界定方法,选取65条远场长周期地震动和50条近场脉冲型地震动,计算各条地震动的10个频谱特征周期参数,通过分析各周期参数与长周期地震动低频特性指标的相关性和离散性,探讨合适的长周期地震动频谱特征周期表征参数。结果表明:5个卓越周期均不能合理地反映长周期地震动的频谱特性,且离散性较大;Hilbert边际谱平均周期T_(mh)评价近场脉冲型地震动频谱特性的合理性不足,Hilbert能量谱平均周期T_(mE)评价近场脉冲型地震动频谱特性的稳定性较差。综合比较相关系数和变异系数的大小后建议加速度反应谱平均周期T_(avg)、T_(mh)作为表征远场长周期地震动频谱特性的特征周期,T_(avg)和加速度反应谱特征周期Tc作为表征近场脉冲型地震动频谱特性的特征周期,且T_(avg)是反映长周期地震动频谱特性的最优周期参数。

The spectrum characteristics of long-period ground motions are important factors that affect the dynamic response of long-period structures,and there is still a lack of research on spectrum characteristic period parameters of long-period ground motions.According to the definition method of long-period ground motions,65 far-field long-period ground motions and 50 near-field pulse-like ground motions were selected to calculate 10 spectrum characteristic period parameters of each ground motion.By analyzing the correlation and dispersion between period parameters and low-frequency characteristic index of long-period ground motions,the appropriate spectrum characteristic period parameters were discussed.The results show that:5 predominant periodcan not reasonably reflect the spectrum characteristics of long-period ground motions,and the dispersion is large;Hilbert marginal spectral average period T_(mh) is not reasonable and Hilbert energy spectrum average period T_(mE) is not stablein evaluatingthe spectrum characteristics of near-field pulse-like ground motions.Based on the comprehensive comparison of correlation coefficients and variation coefficients,Acceleration response spectrum average period T_(avg) and T_(mh) are recommended as the spectrum characteristic period parameters to characterize the spectrum characteristics of far-field long-period ground motion,and T_(avg) and Acceleration response spectrum characteristic period T_(c) are recommended as the spectrum characteristic period parameters to characterize thespectrum characteristics of near-field pulse-like ground motion,and T_(avg) is the optimal period parameter reflecting the spectrum characteristics of long period ground motions.