Long-period ground motion has become an important consideration because of the increasing number of large and long-period structures.Therefore,a thorough investigation on the formation and characteristics of longperiod ground motion is desirable for engineering applications.In this work,an analytical study is performed to examine the effect of several parameters and the combining mode for equivalent harmonic components on the dynamic response of systems.The results of the work show that the harmonic components in equivalent ground motion are evidently influenced by the intensity rise time,duration,phase and combining mode.Moreover,the long-period ground motions are simplified and simulated by separate harmonic components through proper combination.The findings of the work are believed to be useful in the selection of input ground motion in structural seismic analysis.
近断层长周期地震动是一类较特殊的破坏性地震动，对长周期结构的破坏尤为显著。为深入分析近断层地震动的工程特性，基于小波分析中的多尺度分析方法对近期12次典型破坏性地震的53条近断层地震动进行了分解，得到266条地震动分量。通过研究地震动分量的幅值、周期和双规准谱的特征，提出了一种评估近断层区建筑结构地震反应的方法。这种方法能够给出单自由度弹性体系在周期为0.3～20 s 地震动分量作用下的最大绝对加速度反应，并综合考虑了场地和断层距的影响，给出了简洁的函数表达式，为近断层区建筑结构尤其是长周期结构的设计提供了参考依据。
