한국형 원전 격납건물의 해석에 적합한 콘크리트 균열발생기준과 이를 이용한 철근콘크리트 패널의 비선형 유한요소 해석

Abstract

The accurate prediction of concrete crack initiation occurring in the containment building subjected to severe internal pressure has a significant importance in nuclear industry since it directly related to the final safety of nuclear power plant. So far, there have been several experimental researches to find out the material characteristics of the concrete material used at the construction fields of Korean nuclear containment building. Subsequent attempts have been made to suggest some concrete failure envelopes based on these recent experiments. However, further investigations are still required to deduce more rigorous interpretation from the experimental results for inelastic FE analysis of RC structures. In this context, the present study proposes new concrete failure envelope to predict the initial crack initiation of concrete materials under tension-tension and tension-compression stress fields. For this purpose, a standard plasticity model and the Niwa's expression is used to formulate new failure envelopes and the proposed envelopes are then implemented into the finite element analysis program ISADO-RC. Numerical tests on concrete and reinforced concrete panels related to containment building are tackled to show the performance of the proposed failure envelopes. From numerical results, it is found to be that the proposed model performs well to predict the crack initiation and it is adequate to simulate overall failure behaviours of reinforced concrete panels since numerical results obtained with the proposed envelope show good agreements with the existing experimental results.