长周期结构地震瞬态反应研究

Earthquake transient response of a long period structure

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。

The transient response of a structure is usually ignored in traditional dynamic analysis.Based on the theory of harmonic earthquake response and wavelet packet analysis,the transient vibration of a MDOF system subjected to real earthquake ground motion was studied.Response spectra and transient vibration rules of the equivalent SDOF system were analyzed.It was concluded that the maximum displacement of a long period structure may occur in transient vibration and its value is greater than its resonance displacement.By comparing the transient response of a long period building with that of a short period one,it was shown that short period structures are mainly controlled by steady state vibration and the effects of transient vibration on a long period structure is prominent.Therefore,transient displacement and resonance one should be considered in earthquake-resistant design of long period structures.