• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.32-32
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• 2011

최근 국내외에서 친환경건축물에 관한 관심이 매우 높아짐으로 인해 콘크리트의 물량을 절감하여 이산화탄소량을 줄이는 중공슬래브는 다양한 형태로 세계적으로 개발이 되고 있는 추세이다. 특히 이방향 중공슬래브는 환경적인 측면에서 이방향 중공슬래브는 중공부 생성에 재생플라스틱을 활용하여 폐자원을 재사용하고, 콘크리트와 철근의 사용량 절감에 따른 화석에너지 및 이산화탄소 발생량을 감소한다는 장점이 있다. 또한 시스템 측면에서 이방향 중공슬래브는 기존의 철근콘크리트 플랫플레이트 바닥구조 시스템의 자중을 절감하여 구조체를 경량화 시키고, 이에 따라 장스팬 구현이 가능하며, 단열효과가 뛰어나다. 이와 같이 이방향 중공슬래브는 장점이 많지만 플랫플레이트 슬래브의 취약점인 뚫림전단 파괴에 주의해야 한다. 이에 본 연구에서는 선행으로 실시된 이방향 중공슬래브-기둥 접합부 뚫림전단 성능평가 실험을 바탕으로 하여 경량체가 이방향 중공슬래브-기둥 접합부 뚫림전단 성능에 미치는 영향을 살펴보기 위해 범용 유한요소해석 프로그램인 ABAQUS를 사용하여 경량체량 및 위치를 주요변수로 한 해석적인 변화를 검토하였다. 본 연구를 통해 경량체가 삽입된 이방향 중공슬래브의 뚫림전단 성능에 대해, 해석결과 경량체 량과 위치에 따라 최대 뚫림전단강도는 기준 실험체에 비해 74.3%, 73%의 강도저하를 나타내는 것으로 알 수 있었다. 이는 실험상의 강도저하 값인 84.1%, 56.4%와 다소 차이가 있으며, 해석에서 중공부 주위의 응력집중 현상이 제대로 반영되지 않은 것으로 판단된다. 또한 이방향 슬래브에 경량체를 삽입 할 경우 경량체가 시작하는 부분에서 응력이 급격히 감소하는 현상이 나타났으며, 이러한 급격한 응력감소는 기둥 주위 위험단면의 변화를 가져오는 것으로 추정된다. 즉, 위험단면의 변화는 기둥으로부터 경량체 사이의 거리에 따라 달라지며, 위험단면 내의 콘크리트 단면 손실은 뚫림전단 강도를 감소시킨다. 본 연구에서는 이방향 중공슬래브의 뚫림전단강도를 산정할 수 있는 근사식을 제안하였으며, 보다 정확한 이방향 중공슬래브의 뚫림전단강도의 산정식을 위해서는 위험단면의 변화와 콘크리트 단면손실로 인한 전단강도 저하의 관계에 대한 추가적인 연구가 필요하다.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.911-922
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• 2005

A theoretical study was performed to investigate the behavioral chracteristics and shear strength of fiber reinforced concrete slender beams. In the fiber reinforced concrete beam, the shear force applied to a cross section of the beam was resisted by both compressive zone and tensile zone. The shear capacity of the compressive zone was defined addressing the interaction with the normal stresses developed by the flexural moment in the cross section. The shear capacity of the tensile zone was defined addressing the post-cracking tensile strength of fiber reinforced concrete. Since the magnitude and distribution of the normal stresses vary according to the flexural deformation of the beam, the shear capacity of the beam was defined as a function of the flexural deformation of the beam. The shear strength of the beam and the location of the critical section were determined at the intersection between the shear capacity and shear demand curves. The proposed method was developed as a unified shear design method which is applicable to conventional reinforced concrete as well as fiber reinforced concrete.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.539-548
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• 2008

This study aims to determine the applicability of the previously published T-type modular profile beam in the manner of producing specimens designed specially for the said purpose, determining their bending and shear behaviors depending on the presence of shear reinforcement, and analyzing the results in comparison with the theoretical equation of plastic deformation. The modular profile beam contributes to bending and shear resistance with the addition of the profile to the form function, and enhances the molding performance through the modular concept. The experimental results showed that the TS series specimens with shear reinforcement have bending behaviors superior to those of the T series specimens without shear reinforcement, which suggests that the used shear reinforcement appropriately bears the shear force. However, it was considered that all the specimens except for the T1-1 specimen failed to have adequate bending performance because of the intermodular slipping caused by the shear failure of the bolts. It is expected that further studies on the T-type modular profile beam, in which shear connectors will be considered as a variable,be performed to develop optimal intermodular connection methods.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.343-351
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• 2018

Purpose: Recently, As the size of the structure increased, the necessity of reducing its weight was raised. To reduce weight In concrete structures, a hollow slab is proposed as an alternative for weight reduction effect. Method: It is difficult to construct the hollow body due to buoyancy, and the shear performance is insufficient due to the decreased cross section. Slabs were fabricated using unidirectional hollow bodies such as PVC pipes, and experiments were conducted about construction performance and structural performance. Results: The buoyancy preventive device has been improved the construction performance by preventing floating hollow body, it has been confirmed that it has adequate performance to be used as a hollow slab system because it has enough expected shear performance. Coclusion: Hollow ratio has a little connection with bending performance, but after the yielding load, it is necessary to consider the secondary stiffness of structure, and is is supposed that the decrease of shear performance with the increase of hollow core ratio can be complemented with shear reinforcement.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.55-56
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• 2010

Infill walls have been investigated experimentally and theoretically by many researchers during last decades. The objective of this research is to evaluate structural strengthening performance of lightly reinforced concrete with reduced the inside cross-section of Strain-hardening cement composites(SHCC) experimentally.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.75-84
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• 2009

An analytical model for predicting the shear strength of prestressed concrete beams without shear reinforcement was developed, on the basis of the existing strain-based shear strength model. It was assumed that the compression zone of intact concrete in the cross-section primarily resisted the shear forces rather than the tension zone. The shear capacity of concrete was defined based on the material failure criteria of concrete. The shear capacity of the compression zone was evaluated along the inclined failure surface, considering the interaction with the compressive normal stress. Since the distribution of the normal stress varies with the flexural deformation of the beam, the shear capacity was defined as a function of the flexural deformation. The shear strength of a beam was determined at the intersection of the shear capacity curve and the shear demand curve. The result of the comparisons to existing test results showed that the proposed model accurately predicted the shear strength of the test specimens.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.683-695
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• 1997

This paper presents the shear behavior of panel zone in steel frame piers. The results of loading tests on twenty box connections and three types of analysis model are reported herein. It is indicate that the major cause of the reduction of strength and shear deformation capacity (ductility) is the sectional-area ratio and the shear buckling of panel zone. Based on the results, some new proposals are presented for the evalution of strength and ductility of panel zone. This paper is also discussed the ductility of connections by current design procedure.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.197-200
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• 2008

An analytical model for predicting the shear strength of prestressed concrete beams was developed, applying the previously proposed strain-based shear strength model. In flexure-compression member without shear reinforcement, compression zone of intact concrete primarily resist to the shear force rather than tension zone. The shear capacity of concrete at the compression zone was defined based on the material failure criteria. The shear capacity of the compression zone was evaluated along the inclined failure surface considering interaction with the normal stress. Since the distribution of normal stress varies due to the flexural deformation of member, the shear capacity was defined as a function of the flexural deformation. Finally, the shear strength was determined at the intersection of the shear capacity curve and the shear demand curve. As a result of the comparisons to prior test data, the proposed model accurately predicted the shear strength of specimens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.79-86
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• 2008

Four RC shear wall specimens with a/d of 2.2 are designed. And a flexural retrofitting is performed for one specimen by both enlarging wall section and adding additional vertical reinforcements. Also the effectivity of jaketting wall sides is evaluated for the two methods using only steel plate or welded wire mesh with enlargement of section. Cyclic loads are applied to the retrofitted specimens according to the loading history proposed by ACI under constant axial force. Test result showed that the strength and ductility of specimen were improved where the section was enlarged after the installation of additional vertical reinforcements. Confining the ends of wall by U shape W.W.F. with enlargement of section showed most excellent structural capacity regarding to the strength and ductility. Retrofitting by using steel plate was much effective not only to protect the abrupt decrease of strength after yield but also to improve the deformation capacity.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.702-705
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• 2011

본 논문에서는 초고층 전단벽-아웃리거 시스템에 대해, 기존의 근사해석법과 유전알고리즘을 이용하여, 물량최적설계 기반의 구성요소 단면 및 아웃리거 최적위치 결정에 관해 연구를 진행하였다. 아웃리거 시스템의 최적성은 아웃리거의 위치와 아웃리거 시스템을 구성하는 전단벽-아웃리거, 외곽기둥의 단면 성능의 복잡한 관계에 의해 역학적으로 결정된다. 하지만 기존의 아웃리거 시스템의 최적화 연구는 대부분 전단벽과 아웃리거, 외곽기둥의 단면은 고정된 상태에서, 아웃리거의 위치만 설계변수로 하여 아웃리거의 최적위치를 찾는 연구에 국한되어 있다. 이에 본 연구에서는 G.A.를 이용하여, 아웃리거 설치위치뿐만 아니라 전단벽과 아웃리거, 외곽기둥의 단면까지 설계변수로 하여 물량최적설계 조건을 만족시키는 아웃리거시스템의 최적설계 연구를 진행하였다. 또한 반복 계산의 시간을 줄이기 위해 기존의 근사해석법을 사용하였다. 본 연구의 결과는 초고층 구조물의 초기 설계 시에 구성요소의 단면 및 아웃리거 설치 층의 선정에 적극 활용될 수 있을 것이다.