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김승찬,이양우,J. Plank,문주혁 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.6
Tricalcium oxy silicate (C3S) and dicalcium silicate (C2S) are the major constituents of cement. In this study, the reactivity of polymorphs of calcium silicates is quantitatively investigated using Density Functional Theory. The result of combining the DFT calculation and the Bader charge analysis elucidates that the main difference in reactivity between C3S and C2S is the presence of oxy ions in C3S which has smaller partial charge compared to that of other oxygen in the crystals. For the C3S, the reactivity of among different C3S polymorphs is decisively affected by the Bader charge of oxy ions. In contrast, total internal energy of C2S determines the quantitative chemical reactivity of C2S polymorphs. This result suggests that oxy ion has more dominant impact on the thermodynamic stability of calcium silicates. Furthermore, total energy can be used to estimate the chemical reactivity of calcium silicates, where there is no oxy ion exists.
Slab panel vertical support and tensile membrane action in fire
Anthony K. Abu,Ian W. Burgess,Roger J. Plank 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.3
The increasing use of performance-based approaches in structural fire engineering design of multi-storey composite buildings has prompted the development of various tools to help quantify the influence of tensile membrane action in composite slabs at elevated temperatures. One simplified method which has emerged is the Bailey-BRE membrane action method. This method predicts slab capacities in fire by analysing rectangular slab panels supported on edges which resist vertical deflection. The task of providing the necessary vertical support, in practice, requires protecting a panel’s perimeter beams to achieve temperatures of no more than 620°C at the required fire resistance time. Hence, the integrity of this support becomes critical as the slab and the attached beams deflect, and large deflections of the perimeter beams may lead to a catastrophic failure of the structure. This paper presents a finite element investigation into the effects of vertical support along slab panel boundaries on the slab behaviour in fire. It examines the development of the membrane mechanism for various degrees of edge-beam protection, and makes comparisons with predictions of the membrane action design method and various acceptance criteria.
강문명,윤영묵,강성덕,Kang, Moon Myung,Yun, Young Mook,Kang, Sung Duk,Plank, R.J. 한국강구조학회 2005 韓國鋼構造學會 論文集 Vol.17 No.4
본 연구는 온도상승에 따른 압축을 받는 I-형강 보의 플랜지와 웨브의 국부좌굴응력해석을 위한 컴퓨터프로그램과 항복파괴전에 I-형강 보의 플랜지와 웨브에 국부좌굴이 일어나지 않을 최적 폭-두께비를 구할 수 있는 최적알고리즘의 개발이다. 본 연구에서 사용한 고온에 있어서 강재의 응력-변형도 관계식은 EC3(Eurocode3) Part1.2(2000b)를 근거하였다. 본 연구에서 국부좌굴응력과 최적 폭-두께비는 항복응력, 플랜지와 웨브의 국부좌굴계수와 폭-두께비 영향을 고려하여 해석하였다. 그리고 본 연구의 컴퓨터 프로그램을 적용한 설계 예를 들었다. This study involves the development of a computer program to analyze the local buckling stresses for the flange and the web of I-beams under compression at elevated temperatures, and the optimization algorithm to analyze the optimum width-thickness ratios which does not occur their local buckling prior to yield failure. The high-temperature stress-strain relationships of steel used in this study were based on EC3 (Eurocode3) Part1.2 (2000b). In this study, the local buckling stresses and the optimum width-thichness ratios were analyzed considering the influences of the yield stress, local buckling coefficients and width-thickness ratios of the flange and the web. Design examples show the applicability of the computer program developed in this study.