近断层滑冲型地震动频谱特性及强度指标研究

Study on spectral characteristics and intensity indices of near-fault fling-step-type ground motions

我国抗震规范对近断层滑冲型地震动未进行专门规定.通过与普通地震动的反应谱及周期参数的对比分析,探讨近断层滑冲型地震动的频谱特性,并通过分析近断层滑冲型地震动典型强度指标与双线性单自由度体系最大响应的相关性,探讨结构地震反应分析时强度指标的选取问题.结果表明:近断层滑冲型地震动的平均加速度反应谱、速度反应谱、位移反应谱、输入能量谱与滞回耗能谱均明显大于普通地震动,且两类地震动的放大系数具有一定的分布规律;近断层滑冲型地震动各周期参数均明显大于普通地震动,但不同周期参数的变异系数差别较大,各周期参数间的相关性也有较大不同;在进行近断层滑冲型地震动作用下的结构地震反应分析时,建议对短周期结构采用峰值加速度选择与调整地震动输入,而对中、长周期结构采用峰值速度选择与调整地震动输入.

The current China Seismic Code has no special provisions about near-fault fling-step-type ground motions.The spectral characteristics are explored according to the comparative analysis including period response spectrums and period parameters between near-fault fling-step-type ground motions and ordinary ground motions.Besides,in order to explore the selection problems of the intensity indices for seismic response analysis,correlation between intensity indices and bilinear single degree-of-freedom（SDOF）system responses for near-fault fling-step-type ground motions are discussed.The results show that：（1）Response spectrums corresponding to near-fault fling-step-type ground motions are greater than ordinary ground motions.The average peak amplification coefficients of the two types of ground motions have a certain distribution law.（2）All period parameters of near-fault fling-step-type ground motions are significantly higher than ordinary ground motions.Coefficients of variation for different period parameters are different,and the correlation among each period parameter is also different.（3）For short-period structures,peak ground acceleration（PGA）index is advised to be the same as the index for selecting and adjusting ground motion inputs.For medium-to-long period structures,peak ground velocity（PGV）index is advised to be the same as the index for selecting and adjusting ground motion inputs.