受接收设备和记录数量的限制,对摇摆分量内在属性及参数的统计分析了解甚少。为揭示摇摆分量的工程特性,便于结构抗震分析合理选取地震动参数,基于“5·12”汶川8.0级地震的348条数据记录,对比分析平动分量和摇摆分量的幅值以及频谱和持时的空间分布特征和随断层距的衰减规律。研究表明:摇摆分量与平动分量相比,在数量上峰值小很多,能量持时稍小且特征周期偏大。摇摆分量参数的空间分布特征为峰值具有沿断层破裂传播方向的方向性效应,峰值比、特征周期、能量持时的方向性效应不明显; 除特征周期外,峰值、峰值比和能量持时均存在上下盘效应,上盘大于下盘。随断层距的变化特征为摇摆分量参数与平动分量参数的规律性一致,均表现为随断层距的增大,峰值减小, 峰值比、特征周期和能量持时增加。

Limited by the receiving equipment and the number of records,little is known about the rocking component of ground motion which cannot be ignored in structural seismic response analysis. In order to reveal the engineering characteristics of the rocking component and facilitate the reasonable selection of ground motion parameters in structural seismic analysis,based on the “5·12” Wenchuan earthquake records,the spatial distribution characteristics of rocking component's amplitude,spectrum and duration and the attenuation law with the fault distance are discussed. The statistical characteristics of rocking component and translational component parameters are compared. The results show that:compared with the translational component,the peak value of the rocking component is much smaller,the energy duration is slightly smaller,and the characteristic period is larger. For the spatial distribution characteristics of rocking component parameters,the peak value has a directional effect along the direction of fault rupture propagation,while the directional effect of peak value ratio,characteristic period and energy duration is not obvious;Except for the characteristic period,the peak value,peak value ratio and energy duration all have hanging-wall effects. With the change of fault distance,the variation law of rocking component parameters are consistent with those of translational component parameters,which shows that the peak value decreases with the increase of fault distance,and the peak ratio,characteristic period and energy duration.

P315

国家自然科学基金(51969019、51468045)、水利部公益性行业专项(201401009)共同资助