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정제평,Jeong, Je Pyong 대한토목학회 2015 대한토목학회논문집 Vol.35 No.1
최근 Hsu는 전단시험장치를 이용해 순수전단이 작용하는 9개 RC패널요소의 전단시험을 수행하였다(ACI 1997). 최신 트러스모델(수정압축장이론, 회전각연성트러스모델)은 평형조건과 적합조건 그리고 2축 상태에서 RC 막판넬의 연성 응력-변형률 관계를 이용하여 2중 루프의 시행착오방법으로 복잡한 비선형해석을 수행하고 있다. 본 연구는 스트럿과 타이의 파괴기준에 기반한 개선된 모어변형적합방법을 사용해 효율적인 알고리즘을 제안하였고, 이 알고리즘을 이용하여 Hsu가 실험한 전단이력 해석을 빠른 수렴속도로 개선한 것이다. 해석결과에 의하면 전단변형률 증폭상태의 전단변형에너지는 주압축 응력-변형률에 크게 지배받는 것으로 나타났다. Recently, nine $1397{\times}1397{\times}178mm$ RC panels were tested under in-plane pure-shear monotonic loading condition using the Panel Element Tester by Hsu (1997, ACI). By combining the equilibrium, compatibility, and the softened stress-strain relationship of concrete in biaxial state, Modern Truss Model (MCFT, RA-STM) are capable of producing the nonlinear analysis of RC membrane panel through the complicated trial-and-error method with double loop. In this paper, an efficient algorithm with one loop is proposed for the refined Mohr compatibility Method based on the strut-tie failure criteria. This algorithm can be speedy calculated to analyze the shear history of RC membrane element using the results of Hsu test. The results indicate that the response of shear deformation energy at Big Bang of shear strain significantly influenced by the principal compressive stress-strain (crushing failure).
정제평,이창기,유희중,Jeong, Je Pyong,Lee, Chang Kee,Ryu, Heui Joong 대한토목학회 2015 대한토목학회논문집 Vol.35 No.1
This paper is on a practical method for determination of the economical steel ratio in RC flexural members with an equal safety factor. The cost functions of each material and labor are considered to construct the cost function. Then, an equation for determination of the economical flexure steel ratio with the lowest construction cost were proposed. It was found that a relevant steel ratio is recommended to be 0.65~1.0% for designing singly reinforced rectangular beam. 본 연구는 RC 휨부재에서 동일한 안전율을 갖으면서 경제성을 확보할 수 있는 휨 철근비를 결정하는 방법에 관한 실용적 연구이다. 재료비 및 인건비를 고려하여 공사비 함수를 구성하였고, 최저공사비를 유도하는 경제적 휨 철근비를 결정하는 식을 제안하였다. 제안식을 통해 단철근보의 최적 철근비는 0.65~1.0%를 추천하였다.
트러스모델을 사용한 철근콘크리트 구조물의 접합부 설치환경에 따른 우각부 연구
정제평,장승명 한국환경기술학회 2019 한국환경기술학회지 Vol.20 No.4
The purpose of this study is to investigate the amount of rebar reinforcement at corner joints in reinforced concrete structures. As the use of reinforced concrete increases, the use of various types of joints is increasing. Since reinforced concrete corner joints determines the structural performance, research on rebar contents is very important. The current standard design calculation formula of rebar amount is not influenced by geometric shape of corner joint and rigidity ratio of steel. The equations of current standard was a translation of Japanese highway design standards and is different from the US ACI regulations. This study presents a more reasonable design criteria by analyzing the stress distribution through a simple truss model. The effective stiffening efficiency of the stiffener and flexural reinforcement of the corner joint of the box structure was evaluated by comparing with the FEM analysis. As a result of the analysis, it is structurally advantageous to install the hunch, and it is considered that the current design standard which regards the contribution of the rebar as 50 % is not reasonable.
정제평,장승명 한국환경기술학회 2020 한국환경기술학회지 Vol.21 No.2
This study was performed to examine the behavior of time dependent properties on RC columns subjected to high filled soil layer. By using Fortran program which is a modified version for the present purpose, a typical column in reinforced concrete structure was analyzed. Four different model equations for predicted time dependent concrete properties(ACI, CEB-FIP, Bazant & Panula, and Korea Bridge Specification) was employed, and the results were compared. It was found that a relevant creep coefficient is recommended to be 1.0 for designing columns in subway structure subjected by soil dead load, and the soil filling work would be performed at least 3 months later after the concrete casting in order to ensure durability by reducing the negative effect of concrete time dependent properties.
정제평,신근옥,김우,Jeong, Je Pyong,Shin, Geun Ock,Kim, Woo 대한토목학회 2015 대한토목학회논문집 Vol.35 No.1
횡방향 철근이 없는 RC와 PSC 보에서 축방향 인장력은 전단강도를 감소시키고, 축압축력은 전단저항력을 증가시킨다는 것은 잘 알려진 사실이다. 그러나 축력이 전단에 얼마만큼 영향을 미치고, 전단 저항성능에 어떠한 영향을 주는가에 대한 이해가 부족한 현실이다. 횡방향 보강철근이 없는 부재가 큰 압축력과 전단력을 받으면 첫 번째 경사균열이 일어나면서 그대로 취성파괴가 발생하기 때문에 상당히 보수적 관점을 유지하고 있다. 이런 배경에서 ACI의 복부전단강도는 경사균열각 ${\theta}$를 $45^{\circ}$로 하는 트러스모델을 사용하여 스터럽의 수직력과 축력효과를 반영하고 있다. 본 연구는 파괴역학을 근간으로 한 비선형 유한요소해석 프로그램 ATENA-2D (Cervenka, 2000)를 사용하여 철근콘크리트 보의 축력작용에 따른 검증을 수행한 것이다. It is well known that axial tension decreases the shear strength of RC & PSC beams without transverse reinforcement, and axial compression increases the shear resistance. What is perhaps not very well understood is how much the shear resistance capacity is influenced by axial load. RC beams without shear reinforcement subjected to large axial compression and shear may fail in a very brittle manner at the instance of first diagonal cracking. As a result, a conservative approach should be used for such members. According to the ACI Code, the shear strength in web is calculated by effect of axial force and the vertical force in the stirrups calculated by $45^{\circ}$ truss model. This study was performed to examine the effect of axial force in reinforced concrete beams by nonlinear FEM program (ATENA-2D).