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Nonlinear Analysis of RC Members Using Truss Model

트러스 모델을 이용한 철근콘크리트 부재의 비선형해석

  • Published : 2006.04.30

Abstract

Conventional nonlinear finite element analysis requires complicated modeling and analytical technique. Furthermore, it is difficult to interpret the analytical results presented as the stress-strain relationship. In the present study, a design-oriented analytical method using the truss model was developed. A reinforced concrete member to be analyzed was idealized by longitudinal, transverse, and diagonal line elements. Basically, each element was modeled as a composite element of concrete and re-bars. Simplified cyclic models for the concrete and re-bar elements were developed. RC beams and walls with various reinforcement details were analyzed by the proposed method. The inelastic strength, energy dissipation capacity, deformability, and failure mode predicted by the proposed method were compared with those of existing experiments. The results showed that the proposed model accurately predicted the strength and energy dissipation capacities, and to predict deformability of the members, the compression-softening model used for the concrete strut element must be improved.

전통적인 비선형 유한요소해석은 모델링이 복잡하고 어려운 해석기법이 필요로 한다. 게다가 해석결과가 응력-변형률 관계로 도출되므로 그 결과를 분석하거나 설계에 활용하기 어렵다. 본 연구에서는 설계 지향적인 수치해석방법으로 트러스 모델을 이용한 비선형 해석방법을 개발하였다. 해석하고자 하는 철근콘크리트 부재를 길이방향, 직각방향, 대각방향의 트러스요소로 이상화한다. 기본적으로 각 요소는 철근과 콘크리트의 복합체이며, 주기해석을 위하여 철근과 콘크리트 요소를 위한 간략화된 비선형 주기이력모델을 적용하였다. 제안된 방법의 검증을 위하여 전단경간비, 하중조건, 철근량, 배근형태 등이 다른 다양한 전단지배 보와 벽체에 대하여 비선형해석을 수행하였고, 예측된 비탄성강도, 에너지소산능력, 변형능력, 파괴유형 등을 실험 결과와 비교하였다. 해석결과, 철근콘크리트 부재의 변형능력을 예측하기 위해서는 반복적인 인장-압축을 받는 콘크리트 스트럿에 사용되는 압축연화모델이 부재특성에 따라 수정되어야 함이 밝혀졌다.

Keywords

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