【摘要】 高频地震动对长周期结构的影响往往不被重视,结构瞬态振动的作用通常被忽略。借助小波包分解,以简谐地震反应为理论基础进行多自由度体系在实际地震动作用下的瞬态反应计算。通过长周期和短周期结构工程实例的瞬态反应计算,揭示了长周期结构在高频地震动作用下的瞬态振动规律。研究结果表明,结构在低阶振型的振动位移主要受瞬态反应的影响;长周期结构在高频地震动作用下随建筑物高度的增加,瞬态振动的影响愈加显著。因此,高频地震动作用下,长周期结构的瞬态振动不能被忽略,其最大值甚至超过结构在地震激励期间所发生的共振位移,由此提出以结构基本自振频率与激震频率之比值作为划分长、短周期标准的建议。更多还原

【Abstract】 The influence of high frequency earthquakes on long-period structures and the transient responses of such structures are usually ignored.Using wavelet packets transform,the transient response of a MDOF system is calculated based on harmonic earthquake response analysis.With the analyses of two projects,the transient vibration patterns of a long-period building due to high frequency ground motion are eaxmined.It is concluded that the displacement is mainly controlled by the transient response in low order modals.In high frequency earthquakes,the transient displacement of a long-period structure increases with the building height.Therefore,in high frequency earthquake the maximum displacement of a long-period structure could occur in transient vibration and the value could be greater than resonance vibration.A suggestion is made that the ratio of natural frequency to excitation frequency can be employed as the index of criterion for long-period structures.更多还原