典型地震动作用下长周期单自由度体系地震反应分析  

Seismic response analysis of long-period SDOF system under typical ground motions

作　　者：王博[1] 白国良[1] 代慧娟[2] 

机构地区：[1]西安建筑科技大学土木工程学院,西安710055 [2]西安科技大学建筑与土木工程学院,西安710054

出　　处：《振动与冲击》2013年第15期190-196,214,共8页Journal of Vibration and Shock

基　　金：国家自然科学基金项目(50578129)

摘　　要：通过单自由度体系典型地震反应分析探讨长周期结构的类共振及瞬态效应问题。远场类谐和地震动与近断层脉冲型地震动是导致长周期结构发生类共振的两类长周期地震动,而目前对此两类地震动特性以及地震反应的对比分析尚不多见。首先,通过卓越频率与能量时间分布系数对比分析,研究了长周期地震动能量时频分布特性,结果表明:两类长周期地震动的能量均集中在较低频段,且远场类谐和地震动的能量集中频段略低于近断层脉冲型地震动;近断层脉冲型地震动与普通地震动的能量在时域内分布较远场类谐和地震动集中。然后,进行了弹性反应谱对比分析,结果表明:在长周期段,远场类谐和地震动与近断层脉冲型地震动的加速度反应、速度反应、位移反应和输入能量均大于普通地震动,且速度反应、位移反应与输入能量的放大程度明显高于加速度反应;远场类谐和地震动的各反应明显大于近断层脉冲型地震动,且衰减更为缓慢。最后,提出瞬态效应的概念,并进行了实际地震动作用下的瞬态效应分析,结果表明:瞬态效应是地震动高频成分的固有属性,但不足以引起长周期结构的瞬态位移破坏。建议在对长周期结构进行抗震设计时,需要重点考虑两类长周期地震动引起的类共振问题,而不需要考虑瞬态效应。Pseudo-resonance and transient effects of long-period structures were investigated based on the analysis of seismic response of SDOF(single degree of freedom) system.Far-field harmonic-like ground motions and near-fault pulse-like ground motions are two types of long-period ground motions which can lead to pseudo-resonance of long-period structures.Based on the contrast analysis on predominant frequency and energy distribution coefficient,characteristics of time-frequency energy distribution of long-period ground motions were analyzed.The results show that: the energy of two types of long-period ground motions are concentrated in lower frequency bands,especially far-field harmonic-like ground motions;in time domain,the energy distributions of near-fault pulse-like ground motions and ordinary ground motions are more concentrated than that of far-field harmonic-like ground motions.The elastic response spectra were comparatively analyzed and the results show that: in long-period bands,the magnitudes of response spectra corresponding to far-field harmonic-like ground motions and near-fault pulse-like ground motions are greater than that corresponding to ordinary ground motions,especially the velocity response spectrum,displacement response spectrum and input energy spectrum;all kinds of reactions for far-field harmonic-like ground motions are much greater than those of near-fault ones and the attenuation of the former is much more slowly.The concept of transient effect was put forward,and transient effects of actual ground motions were analyzed.The results show that: transient effects are natural attributes of high-frequency components of ground motions,which couldn't cause transient deflection damage of long-period structures.In long-period structural seismic design,it is necessary to consider the pseudo-resonance caused by two types of long-period ground motions,while it is unnecessary to consider transient effects.

关 键 词：长周期地震动 能量时频分布 反应谱 瞬态效应 长周期单自由度体系 

分 类 号：TU311.3[建筑科学—结构工程]