近断层长周期脉冲型地震动对竖向反应谱影响研究

长周期大幅值脉冲运动是近断层地震动的重要特征,也是引起结构震害的重要因素。在既有的地震动数据库基础上,筛选建立了长周期脉冲型记录的统计样本库,并构建了地震动特征参数的回归关系式。针对竖向反应谱,深入分析了竖向分量与水平向分量的加速度反应谱比值随脉冲周期和结构自振周期的变化规律,结果表明反应谱比值显著大于现行规范取值,进而采用分段线性化方法,建立了竖向反应谱比值随脉冲周期、自振周期变化的简化关系式,并对影响竖向反应谱曲线各拐点周期的特征比值进行统计分析,拟合得到了其随震级和断层距的衰减模型。

Influence of near-fault long-period pulse-type earthquake ground motions on vertical response spectra

The long-period large-amplitude pulse is a remarkable characteristic of near-fault earthquake ground motions,which is also an important factor leading the structure to damage or collapse.The database and regression relation for near-fault long-period pulse-type earthquake records were established based on the available data.The influence of pulse period and structural natural vibration period on the acceleration response spectra ratio of vertical to horizontal components was discussed in-depth.The response spectra ratios obtained from near-fault long-period pulse-type records are greater than those given by existing seismic design codes.The simplified relationship of response spectra ratio obtained by using piecewise linearization method varies as a function of pulse period and structural natural vibration period.The statistical results and attenuation relationship of characteristic ratio for vertical response spectra curves were given,which controls the inflection point periods of vertical response spectra and is related to earthquake magnitude and fault distance.