双向地震动作用下刚度偏心单层体系弹性反应谱研究

RESEARCH ON ELASTIC RESPONSE SPECTRUM OF ONE-STOREY ASYMMETRIC PLAN SYSTEM SUBJECTED TO BIDIRECTIONAL GROUND MOTION

目前的工程抗震设计方法是建立在弹性单自由度反应谱的基础上,然而实际地震动的多维性和结构偏心引起的空间耦合性使得基于单自由度反应谱的设计方法存在着局限性。为此,研究并建立了双向地震作用下结构刚度偏心层体系弹性反应谱模型,定义弹性位移比值谱和加速度比值谱。通过对硬土、中硬(软)土、软土3类场地60条双向地震动的弹性比值谱统计平均结果,分析3类场地比值谱的谱值分布特征及相对刚度偏心距、扭转频率比对谱值及谱值分布的影响。结果表明,各类场地的比值谱都具有独特的谱值分布特征,并且这些分布特征受相对刚度偏心距和扭转频率比的影响较小。在每种场地类型的谱值分布特征下,弹性比值谱随相对刚度偏心距和扭转频率比的变化也具有一定的规律性。

The limitation in the application of elastic response spectra of one degree of freedom system is presented and its model is developed in considering the bidirection earthquake excitation.The elastic ratio response spectrum is also introduced.The ratio spectrum distribution pattern and the effects of normalized stiffness eccentricity and rotation frequency ratio on spectrum amplitude are discussed by use of statistic analysis of 30 recordings under bidirectional earthquake excitation in the cases of hard site,medium site and soft site.The analysis shows that the ratio spectra distribution pattern on each kind of site is of regularity and is affected hardly by normalized stiffness eccentricity and rotation frequency ratio,while the effect of these factors on the spectrum amplitude is obvious and is also of certain regularity.