摘要：传统动力学理论通常认为地震瞬态反应可以忽略。基于简谐地震反应的基本理论，引进小波包分解技术，推导了实际地震动作用下，多自由度体系瞬态反应的计算方法。分析了等效单自由度体系的反应谱特性以及瞬态振动的规律。明确了长周期结构的最大位移可能出现在结构瞬态振动中，其值甚至超过结构在地震激励期间所发生的共振位移。通过实际地震动作用下长、短周期结构瞬态反应的比较，表明短周期结构主要由稳态振动控制，而长周期受瞬态振动影响显著。因此，长周期结构抗震不仅要避免共振发生，还须充分考虑到结构瞬态振动的位移破坏。

Abstract: The transient response of a structure is usually ignored in traditional dynamics. Based on the theory of harmonic earthquake response and wavelet packets analysis, the transient vibration of MDOF systems subjected to real earthquake ground motion is derived. Response spectra and transient vibration rules of equivalent SDOF system are got. It is concluded that the maximum displacement of a long period structure could occur in transient vibration and the value could be greater than sympathetic vibration. By comparing the transient response of a long period building with that of a short period building, it is shown that short period structure is mainly controlled by steady state vibration and the effects of transient vibration on a long period structure is prominent. Therefore, transient displacement as well as sympathetic displacement must be considered in the earthquake-resistant design of long period structures.