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이득행 ( Lee Deuck Hang ),김강수 ( Kim Kang Su ) 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.13 No.1
In existing post-tension(PT) slab system, anchorage is typically located at the edge of slab, and temporary installations of additional froms are required to set the anchorage. In previous research, authors proposed the top jacking anchorage system to improve the constructability of existing PT methods. The stress distribution at anchorage zone, however, is very different from the existing systems because jacking at interior slab induces tensile stresses at the back of anchorage. Structural design provisions have not yet suggested the design details suitable for proposed anchorage system. Therefore, this research presents a detailed design example including reasonable reinforcement details resisting against the spalling, bursting, and tensile stresses at the back of anchorage based on code requirements and strut-tie model.
이득행(Lee Deuck-Hang),김강수(Kim Kang-Su),김상식(Kim Sang-Sik),박정우(Park Junng-Woo),최일섭(Choi Il Sup),임주혁(Lim Joo-Hyuk) 대한건축학회 2008 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.28 No.1(구조계)
Post-tension (PT) slabs are generally classified by the tendon lay-out as concentrated type, distributed type, and combination type, whose deflection depends on the tendon lay-out and its amount. Finite element analysis were performed to analyze the efficiency of deflection control by primary parameters; distribution types of tendons and ratios of prestressed reinforcement. Based on analysis results, economic efficiency was estimated considering both material and construction cost. In this study, the increase of construction cost and the efficiency of deflection control by partial PT method with top anchorage were also included. The results of this study indicate that the partial PT method with top anchorage is very efficient for deflection control and can save the amount of tendon by applying tendons in a part of span required due to large deflection anticipated. The application of the partial PT method with top anchorage increase the construction cost about 6% compared to that in RC structure, which is considered to be reasonable cost for the important deflection control.
파형웨브가 적용된 프리스트레스트 매립형 합성보의 휨거동
이득행(Lee Deuck-Hang),방용식(Bang Yong-Sik),김강수(Kim Kang-Su),최성모(Choi Sung-Mo),김진호(Kim Jin-Ho),최일섭(Choi Il-Sup) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)
The demand for long span, reduction of floor-to-floor height is increased recently as buildings become bigger and higher. If the steel beam, however, becomes bigger, it is difficult to take advantage of merits of steel materials because of instability for buckling, excessive deflection, and failure of fatigue and if the concrete beam becomes bigger, it causes the problem of excessive crack and deflection. It, therefore, is difficult to realize the long span and reduction of floor-to-floor height simultaneously. The research to develop composite beam systems is increased gradually to overcome such limits. In the early time, the composite systems just consist of concrete and I-shape steel. The prestressing method, however, is introduced in composite beam systems because it is difficult to satisfy the demand for control of deflection and required strength by using composite beam systems which just put two materials together. The existing prestressed composite beams are not effective to introduce prestressing force because of high axial stiffness of I-shape steel. In this paper, the prestressed composite beam applied corrugated steel web that has high efficiency of prestressing force introduction and crack control ability, and high strength as results of effect of stress concentration to upper, lower flange which is known as Accordion Effect and increase of bearing area is proposed to improve the existing composite beams, propose the flexural behavior prediction model of proposed composite beam and simple horizontal shear strength prediction equation which takes account of the failure by separation of lower steel beam from upper slab that is different failure mode from previously reported failure modes, effect of concrete shear strength at the failure surface newly defined and inclined steel strand. The tests of one composite beam applied corrugated web and two prestressed composite beams applied corrugated web were conducted to verify the reliability of the proposed flexural behavior prediction model that takes account of Accordion Effect by assuming just the area near upper, lower flange can resist axial force and using Effective Area and Effective Moment of Inertia. Proposed model predicted the flexural behavior of the composite beams applied corrugated steel web accurately, the strain at the top of the section very well, the amount of steel strand stress increment with high reliability at each loading step, and the horizontal shear strength accurately.