Effect of Spatial and Directional Variability of Seismic Ground Motion on the Response of Structures

抗震结构的分析和设计需要对现场预期的地面震动进行可靠的估计。目前评估这些地震地面运动特征的程序往往是经验性的，所得出的估计仅限于特定的地震和为其制定这些特征的场地。因此，这种分析的结果可能不适用于结构的一般地震反应分析。这项研究计划的任务是为影响场地地震运动的描述参数建立可靠的估计。为此，使用了SMART-1(台湾强震台阵)的大量记录地震数据和新开发的将运动分解为其主导波分量的技术。对一些地震的场地优势波特征的分析，为评估地震运动的随机特征(三个垂直方向的运动的功率和交叉谱密度、旋转分量及其空间变异性)的一般表达式提供了基础。将运动的随机描述与地震和场地特征联系起来的衰减方程的发展正在探索中。

The analysis and design of structures for earthquake resistance requires reliable estimates of the ground shaking expected at the site. Current procedures for the evaluation of these seismic ground motion characteristics tend to be empirical and result in estimates that are restricted to the particular earthquake and site for which they were developed. The results of such analyses therefore may not be suitable for general seismic response analyses of structures. This research program addresses the task of establishing reliable estimates for the description parameters that influence the seismic motions at a site. The multitude of recorded earthquake data at SMART-1 (Strong Motion Array in Taiwan-1) and the newly developed techniques for decomposing the motions into their dominant wave components is used for this purpose. The analysis of the dominant wave characteristics at the site for a number of earthquakes provides a basis with which to evaluate general expressions for the stochastic characteristics of the seismic motions (power and cross spectral densities of the motions in three orthogonal directions, their rotational components and their spatial variability). The development of attenuation equations that relate the stochastic descriptions of the motions with the earthquake and site characteristics is being explored.