六分量地震动实测记录的时频特征分析

Time-Frequency Characteristic Analysis of Six-Degree-Freedom Ground Motion Records

至今国内外对地震动的三个平动分量已进行了较为充分的研究,但对含三个转动分量的六分量地震动记录的研究尚显不足.利用我国台湾东部HGSD台站在2007-2008年间的52次地震的六分量地震动的实测记录,分析了平动分量中竖向地震动与水平向地震动峰值比和转动分量中扭转地震动与摇摆地震动的角速度峰值比随震中距的变化.在此基础上,选择一组典型的含三个转动分量的六分量地震动记录,采用正交化HHT(Hilbert-Huang Transform)法对各分量的时频特征进行了对比分析.结果表明:在近震区域存在较大的竖向地震动,扭转分量的角速度峰值总体上大于摇摆分量的角速度峰值;各个分量上的能量分布存在差异,转动分量的卓越频带较平动分量宽;转动分量中的摇摆分量较扭转分量含有更多的高频成分.

So far, the three translational components of earthquake ground motion have been studied widely both in domestic and abroad research field of earthquake engineering, but the research on six components of ground motion including the rotational components is still inadequate. In this paper, the real records of six components of 52 local earthquakes at the HGSD station in eastern Taiwan from 2007 to 2008 were collected, and the ratio of translational vertical and horizontal components peak acceleration, and also the ratio of torsional and rocking components peak rotational velocity according to the epicentral distances were analyzed. Then the six components of a specific earthquake were chosen and analyzed and compared between each component by using orthogonal HHT （Hilbert-Huang Transform） method. The result shows that： the translational vertical components seem to be relatively bigger in near field zones, and the peak rotational velocity of torsional components are bigger than corresponding rocking components for most cases; the energy distribution is different for different ground motion component, the dominate frequency band of rotational components is wider than that of translational components, and for the rotational components, the rocking components contain relatively more high frequencies than the torsional components.