场地特征周期插值研究

Study on the interpolation of site characteristic period

场地特征周期T_g作为反应谱平台段的终止周期值,在规范中除了有明确的取值规定外,还允许按照(等效)剪切波速和覆盖层厚度通过连续插值的方法得到。规范中给出了插值的参考图和插值的连续性原则。仔细研究发现,规范中给出的T_g插值参考图在分区间和台阶转换处,存在着插值密度不连续的情况。从不同分区间的过渡和台阶转换的两个角度出发,推导出插值密度连续的T_g插值方案,推导了有台阶转换的插值方案,不仅解决了分区间插值密度连续的问题,同时也实现了Ⅲ区内的台阶转换的连续性问题,解决了规范中隐含的连续性插值分区内的插值密度连续性问题,使插值过程更加严谨,还同时给出了满足工程精度的实用方法,可为实际工程设计提供参考。

As the turn point of spectrum curve,the value of the characteristic period T_g is not only explicitly defined in the code,but also be interpolated on basis of(equivalent) shear velocity and overlay thickness.The code prescribes the smoothness principle of interpolation.On scrutinizing,the T_g interpolation reference diagram given by code is not smoothly transferred through regions and step-transition.From views of inter-region transfer and step-transition,a smoothly transferred interpolation scheme was proposed.