弱非线性下两种程序对不同类别场地地震反应的对比

A Comparison of the Seismic Responses at Different Sites byTwo Analysis Programs under Weakly Nonlinear Conditions

摘要:

一维等效线性化土层地震反应分析程序的代表有LSSRLI 1与SHAKE2000。LSSRLI 1是我国地震安评工作中推荐使用的程序，代表20世纪80年代的国际先进水平，而目前代表国际先进水平是SHAKE2000。针对等效线性化程序存在的不足，有必要对LSSRLI 1进行改进。为了寻找LSSRLI 1与SHAKE2000之间的差异，通过建立Ⅰ至Ⅳ类场地的土层剖面模型，对比分析两程序的计算结果，得到在不同场地条件下两程序的差异情况以及这些差异的变化规律。结果表明，Ⅰ、Ⅱ类场地中两程序计算结果差异不大，Ⅲ、Ⅳ类场地中两程序计算的PGA、反应谱与剪应变结果差异较大。初步分析可知，剪应变相对差与PGA、反应谱、剪切模量相对差存在相关性，通过修正剪应变的计算可以缩小LSSRLI 1结果与SHAKE2000结果的差距。

Abstract:

The one-dimensional equivalent linear method for soil layer seismic response analysis is widely used in engineering practices and academic fields. LSSRLI-1 and SHAKE2 000 are typical codes.LSSRLI-1，which represents the 1980s skill level，is recommended in Chinese manuals on seismic safety evaluation practices.SHAKE2 000 represents a more internationally advanced level.Improvements to LSSRLI-1 must be made with respect to the drawbacks of the equivalent linear method it uses.To reveal the differences between LSSRLI-1 and SHAKE2000，we established a horizontal layered model for class-Ⅰ to class-Ⅳ sites.Then we ran the two programs on the same working cases.A comparison and statistical analysis of the results shows the difference between the two programs and we therefore propose a variation of the relative deviation rule.Results indicate that peak ground acceleration （PGA），the spectrum，and the shear strain results do not obviously coincide in class-Ⅲ and class-Ⅳ site conditions. But in class-Ⅰ and class-Ⅱ sites conditions，there is little difference between the results of the two programs.After preliminary analysis，we conclude that the shear strain calculation method can be improved by modifying the shear modulus method to narrow the gap between LSSRLI-1 and SHAKE2000 results.We make this conclusion on the basis of the relative relationships between the shear strain，the PGA，the spectrum，and the shear modulus relative deviation.