基于SSI效应的结构抗震设计方法的中美规范对比

Comparison of structural aseismic design method based on soil structure interaction effect between Chinese code and American code

考虑地基与结构相互作用(SSI)效应后,结构的周期延长、阻尼增加,结构所受地震作用发生变化。建造于软弱地基上的高层建筑受此效应影响更显著。为优化中国规范基于此效应的抗震设计方法,从实现方法、地震作用的折减方法、应用范围、折减系数沿度高变化等方面,对中美抗震设计规范中基于SSI效应的结构抗震设计方法进行详细对比分析。研究结果表明结构动力参数的修正是中美SSI条文的核心差异,中国抗震规范的方法简单、方便,但没有美国抗震规范精细、全面;美国抗震规范SSI条文中考虑了结构重力二阶效应的影响,但中国抗震规范却未考虑。根据对比分析结果,对中国抗震规范关于SSI条文提出相应的修改建议。

If the effects of soil-structure interaction(SSI) is considered, the period and damping of the structure will be increased, and the earthquake action to the structure will be changed. For high-rise building built on soft soil, the influences caused by SSI are more intense. In order to optimize seismic design method considered SSI effect, a detailed comparison between Chinese and American code was given. The comparison was mainly conducted among principle, reduction method of earthquake action, application scope, and the change of reduction factor with height. The results show that dynamic parameters' revision is the main difference between Chinese and American code'SSI provisions, the method in Chinese aseismic code is more simple and convenient, but American aseismic design code is more complex and comprehensive. Besides, American code has considered the influence of gravity second-order effect in the SSI provisions, instead of Chinese code. For that, some suggestions are given for the method's revision of Chinese aseismic code.