确定核电厂设计地震动输入分析模型的比较

Comparation on the nuclear power plant design ground motions with different analysis model

由于抗震设防较高的核电厂核岛结构通常具有三维尺寸大且重量较大的特点,因此确定这类地震输入时所建立的合理分型模型还需要深入研究。本文参考核电抗震规范要求,分别建立了不考虑土-结构相互作用(SSI)及考虑SSI的水平成层地表地震动分析模型,对不考虑SSI的地震动分析模型,分别采用线性及以一维等效线性化方法计算场地地表反应,对考虑SSI的地震动分析模型,首先建立三维土-结构相互作用线性场地有限元模型计算地震输入,其次建立修正模型考虑非线性特征。分析表明考虑SSI作用时,获得的核电厂地震输入,与不考虑SSI作用只考虑土层特征获得的地震输入及基岩地震记录均存在差异。覆盖土越"刚",反应谱差异虽然越小,但SSI作用越明显。考虑非线性影响时,其地表地震动反应结果一般小于线性分析时结果,且覆盖土层越"柔",差距越大。

Due to the nuclear island structure with high seismic fortification level and it usually has large 3D size and high weight,so determining the seismic input of the reasonable models are needed to study deeply. Based on the nuclear seismic code,both model without considering soil structure interaction( SSI) and model with horizontal layered considering SSI are built. Without considering SSI model,the linear and the equivalent linear method are used to calculate ground motions. With considering SSI model,the linear and the revised equivalent linear method are used to calculate seismic input. It showed that considering SSI,the seismic input results are different from the bedrock records and the free field model in general. Harder the covering soil,less difference among response spectra of acceleration but bigger the influence of SSI on ground motion. Considering nonlinear character,the results of ground motion generally are smaller than not considering that,and softer the covering soil,more difference among the results.