• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.193-196
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• 2008

This paper proposes a method to predict the ductility capacity of reinforced concrete beam-column joints failing in shear after the formations of plastic hinges at both ends of the adjacent beams. The current design code divides joints into two categories: Type 1 for structures in non seismically hazard area and Type 2 in seismically hazard area. While there are many researches related to joint shear strength in Type 1, those in regard to joint ductility capacity of Type 2 are scarce. This paper classified the ductility capacity of beam-column joints into column, joint panel, and beam deformability. Since a brittle failure such as shear or bond failure in the columns must be avoided, column deformability was calculated by elastic analysis. The plastic hinges of the adjacent beams affect joint deformability. Therefore, the prediction of joint deformability was calculated with consideration to the degradation of the diagonally compressed concrete due to the strain penetration.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.741-751
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• 2010

An experimental study was performed to investigate the earthquake resistance of the beam-column connections as a part of a precast concrete moment-resisting frame that uses precast concrete U-shaped shells for the beams. Five full-scale precast concrete specimens and one conventional monolithic concrete specimen were tested under cyclic loading. The parameters for this test were the reinforcement ratio, stirrup spacing, and end-strengthening details of the precast beam shell. The test results showed that regardless of the test parameters, the precast concrete beam-column connections showed good load-carrying capacity and deformation capacity, which were comparable to those of conventional monolithic concrete specimen. However, at large deformations, the beam-column connections of the precast concrete specimens were subjected to severe strength degradation due to diagonal shear cracks and the bond-slip of re-bars at the joint region. For this reason, the energy dissipation capacity and stiffness of the precast concrete specimens were significantly less than those of the cast-in-place specimen.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.25-32
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• 2006

In this study the seismic performance of welded steel moment connections to built-up box columns in the existing building built before 1994 Northridge earthquake was evaluated by cyclic tests. According to the test results, the pre-Northridge steel moment connections to the box columns also suffered from brittle fracture similar to that in the H-shaped column connections. However, the flange force transfer mechanism of the box column connections was substantially different from that of the H-shaped column connections, and the patterns of crack propagation may be changed due to the shape of the box column. Therefore, it is required to develop proper details for the box column connections instead of using the research results for H-shaped column connections in order to enhance the seismic performance the connections.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.10-13
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• 2011

내진설계의 기본 개념은 보를 기둥보다 약하게 설계하여 보에 소성힌지를 발생시켜 구조물 전체의 큰 변형을 방지하는 것이다. ACI 352R-02에서는 지역의 지진특성에 따라서 접합부의 상세 설계법을 구분하여 적용한다. 하지만 보와 접합부의 내력 차이가 상대적으로 작게 설계된 구조물의 경우 탄성 범위를 유지해야 하는 경우의 접합부에도 파괴가 발생할 가능성이 있다. 횡하중이 작용할 때 접합부 내부는 전단력의 지배를 받게 되고, 전단내력과 부착내력에 따라서 파괴모드가 결정된다. 본 논문에서는 양방향 반복하중이 작용하는 10개의 보-기둥 접합부를 통해서 접합부와 인접보의 전단내력 차이에 따라서 발생하는 파괴모드를 관찰하고 접합부 내의 전단내력 및 부착내력의 감소로 인해 발생하는 부재의 연성에 대해서 관찰하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.341-346
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• 2002

이 연구는 게르버 보 형식의 포스트텐션 PC 골조 구조 시스템의 실용화를 위해 골조 전체의 구조 성능 시험을 수행하며, 여기서 보-기둥 접합부 및 내민 보-단순 보 접합부의 구조 성능과 골조의 안전성을 확인한다. 시험은 400 mm$\times$800 mm 단면의 경간 3 m 보와 500 mm$\times$600 mm 단면을 갖는 높이 3 m 기둥의 실물 크기 시험체를 제작하여, 기둥에 80 톤의 축 하중을 준 상태에서 단순 보 중앙에 하중을 가력하여 기둥-보 접합부와 단순 보-내민 보 단면 축소 연결부의 구조성능을 파악한다. 시험 결과, 보 - 기둥 접합부는 예상 설계 하중 40톤 이상에서도 강 접합에 가깝게 거동하였고, 단순 보- 내민 보의 단면 축소 연결부는 경사철근의 사용으로 초기 균열 및 균열 확산에 대한 억제 효과가 있었으며, 예상 설계 전단력 40톤에서 안전하다는 것이 확인되었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.5
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• pp.1-9
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• 2007

This study summarizes the results of a research project aimed at investigating the inelastic rotation capacity of beam-column connections of reinforced concrete moment frames. A total of 91 test specimens for beam-column joint connections were examined in detail, and 28 specimens were classified as special moment frame connections based on the design and detailing requirements in the ACI 318-02 Provisions. Then the acceptance criteria, originally defined for steel moment frame connections in the AISC-02 Seismic Provisions, were used to evaluate the joint connections of concrete moment frames. Twenty-seven out of 28 test specimens that satisfy the design requirements for special moment frame structures provide sufficient strength and are ductile up to a plastic rotation of 0.03 rad. without any major degradation in strength. Joint shear stress, column-to-beam flexural strength ratio, and transverse reinforcement ratio in a joint all play a key role in good performance of the connections.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.23-34
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• 2000

반복하중을 지지하는 4개의 2/3 크리 접합부 실험을 통하여 콘크리트 기둥 및 강재 보로 구성된 골조에 대한 외부 모멘트 접합부의 이력거동을 조사하였다. 주요 실험 변수는 접합부에 배치된 후프근의 수, 콘크리트만의 전단강도 발현응ㄹ 유도한 접합부 상세, 강재 보 플랜지 상, 하부에 스터드 형태의 전단키를 사용한 상세 등이다. 실험 시 관측된 균열양상, 파괴형상 및 다양한 계측결과에 근거하여 접합부 상세에 따른 각 시험체의 거동이 자세히 기술되었으며, 항복 후 보유강도, 강성저하 정도 및 에너지 소산능력 등이 분석되었다. 실험결과에 의하면, 이들 중 패널 및 인접 기둥 영역에 각각 2개의 후프근을 갖는 시험체 (CF3) 가 가장 우수한 이력응답을 나타냈으며, 이러한 형태의 접합부 상헤는 우리나와 같은 약진 지역에 적합할 것으로 판단되었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.63-68
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• 2007

The purpose of this study was to develop a new connection method between steel beams and PC columns known as SL connectors. Composite moment frames consisting of PC columns (or composite columns) and steel beams make the best use of advantages of both concrete and steel materials. However, the connection between two members of different materials can be complex and/or increase the fabrication costs significantly. The concept of SL connectors is based on using wedges and the emphasis is on a self-locking (SL) feature. SL connectors are easy to install and provide better seismic performance compared to conventional connections. To evaluate the seismic performance of the steel beam-to-PC column joints with SL connectors, cyclic load tests were conducted. Test result showed that steel beam-to-concrete column joint with SL connectors was able to provide sufficient performance for use in seismic resistant moment frames.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.2
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• pp.29-36
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• 2009

The present study emphasizes a nonlinear model to predict the shear behaviour of reinforced concrete interior beam-column joints. To model the shear behaviour of a panel zone in the beam-column joint, a modified softened truss model theory for in-plane shear prediction was introduced. This relationship was changed to define the characteristics for the rotational spring to represent the shear deformation in the joint by an equivalent moment-rotation relationship from the joint equilibrium. The analysis model was compared with experiments on reinforced concrete interior beam-column joints that were subjected to axial and shear forces, and the current model was found to accurately predict not only the shear force but also the shear deformation in the joint.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.517-524
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• 2012

In this study, the effects of the inelastic shear behavior of beam-column joint and the vertical distribution of lateral load are evaluated considering higher modes on the response of RC OMRF using the pushover analysis. A structure used for the analysis was a 5-story structure located at site class SB and seismic design category C, which was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was identified using fiber model. Also, bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The results of pushover analysis showed that, although the rigid beam-column joint overestimated the stiffness and strength of the structure, the inelastic shear behavior of beam-column joint could be neglected in the process of structural design since the average response modification factor satisfied the criteria of KBC2009 for RC OMRF independent to inelastic behavior of joint.