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콘크리트 재료의 동적 물성 변화를 모사하기 위한 유변학적(Rheological)모델 개발 및 평가

Rheological Models for Simulations of Concrete Under High-Speed Load

  • 황영광 (연세대학교 토목환경공학과) ;
  • 임윤묵 (연세대학교 토목환경공학과)
  • 투고 : 2015.03.20
  • 심사 : 2015.06.11
  • 발행 : 2015.08.01

초록

본 연구에서는 속도 의존성을 나타내는 콘크리트의 인장거동을 모사하기 위하여 유변학적(rheological) 모델을 개발하였고 이를 평가하였다. 일반적으로 외부에서 가해지는 하중 속도가 증가할수록 콘크리트의 물성(강도, 탄성계수, 파괴에너지 등)은 그 크기가 증가한다. 콘크리트의 강도는 다른 물성에 비하여 큰 속도의존성을 나타내고, 압축 하중인 경우보다 인장 하중을 받는 경우 그 속도의존성이 크게 나타난다. 이러한 콘크리트의 속도 의존성을 모사하기 위하여, 기존 RBSN(Rigid-Body-Spring-Network) 모델의 거동을 나타내는 스프링 세트에 대쉬포트(Dashpot)와 같은 점성 요소와 Coulomb 마찰 요소를 조합하였다. 요소의 조합에 따라 세 가지 모델( 1)점탄성, 2)점소성, 3)점탄소성 손상(Damage 모델)을 고려하였고, 이에 대한 구성관계식을 유도하였다. 개발된 해석모델은 직접인장 실험의 응력-변형률 관계곡선과 비교 검증되었고, 이중 점탄소성 손상 모델은 실험결과를 잘 모사할 수 있음을 확인하였다.

In this study, the rheological models were introduced and developed to reflect rate dependent tensile behaviour of concrete. In general, mechanical properties(e.g. strength, elasticity, and fracture energy) of concrete are increased under high loading rates. The strength of concrete shows high rate dependency among its mechanical properties, and the tensile strength has higher rate dependency than the compressional strength. To simulate the rate dependency of concrete, original spring set of RBSN(Rigid-Body- Spring-Network) model was adjusted with viscous and friction units(e.g. dashpot and Coulomb friction component). Three types of models( 1) visco-elastic, 2) visco-plastic, and 3) visco-elasto- plastic damage models) are considered, and the constitutive relationships for the models are derived. For validation purpose, direct tensile test were simulated, and characteristics of the three different rheological models were compared with experimental stress-strain responses. Simulation result of the developed visco-elasto-plastic damage(VEPD) model demonstrated well describing and fitting with experimental results.

키워드

참고문헌

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피인용 문헌

  1. Validation of three-dimensional irregular lattice model for concrete failure mode simulations under impact loads vol.169, 2017, https://doi.org/10.1016/j.engfracmech.2016.11.007
  2. Simulation of concrete tensile failure under high loading rates using three-dimensional irregular lattice models vol.101, 2016, https://doi.org/10.1016/j.mechmat.2016.08.002
  3. Rate Dependent Behavior of Reinforced Concrete Using Irregular Lattice Model vol.431, pp.1757-899X, 2018, https://doi.org/10.1088/1757-899X/431/11/112008