• 콘크리트학회논문집
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• 제14권6호
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• pp.823-829
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• 2002

철근콘크리트 기둥-철골 보 합성골조는 철근콘크리트와 철골부재의 재료적인 장점을 살린 합리적인 구조물이나, 이질 재료간의 접합으로 인해 보-기둥 접합부의 설계와 해석에서는 많은 구조적인 문제점들이 생기게 된다. 이 연구에서는 철골 보의 하중이 콘크리트 기둥으로 원활히 전달되면서 현장 시공성이 우수한 새로운 형태의 합성골조 접합부의 형식을 제안하고자 한다. 이 연구에서 고안된 접합부는 H 형강을 반분한 T 형강을 시스템 내부 및 외부의 모든 응력 전달 요소를 연결하는 주요 요소로 하고, 보 플랜지의 인장력 전달을 위해 한 방향은 고강도 강봉을, 이와 직교하는 방향은 강재 연결판을 사용하였다. 스티프너보강된 ㄱ형강을 사용하여 보 플랜지의 인장력을 기둥면에 전달하도록 하였으며, T 형강에 용접된 전단 접합판을 보의 웨브와 고력볼트로 접합하여 전단력을 지지하도록 설계하였다. 이 연구에서는 보의 플랜지로부터 스티프너 보강된 ㄱ형강을 통해 강봉이나 연결판으로 전달되는 휨모멘트 전달성능을 확인하고자 구조성능 시험을 수행하였다. 시험체는 실제 보-기둥 접합부를 모델로 하여, 실물크기로 4개가 제작되었으며, 구조실험은 철골 보의 양 단부를 단순지지한 상태에서 기둥 중앙에 집중하중을 가해 보-기둥 접합부에 휨모멘트와 전단력을 작용시키는 방식으로 진행되었다. 실험결과, 이 연구에서 제안된 접합부는 현장 적용이 가능한 가공성과 운반성 및 시공성을 가지며, 철골 보-접합용 ㄱ형강 -연결용 강봉 및 연결판에 의한 응력전달이 매우 순조로운 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제18권4호
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• pp.389-410
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• 2004

In this study, theoretical and experimental results are presented which were obtained during an investigation of the influence of the $P-{\Delta}$ effect that was caused by the simultaneous changing of the axial load P of the column and the lateral displacement ${\Delta}$ in the external beam-column joints. The increase or decrease of ${\Delta}$ was simultaneous with the increase or decrease of the axial compression load P and caused an additional influence on the aseismic mechanical properties of the joint. A total of 12 reinforced concrete exterior beam-column subassemblies were examined. A new model, which predicts the beam-column joint ultimate shear strength, was used in order to predict the seismic behaviour of beam-column joints subjected to earthquake-type loading plus variable axial load and $P-{\Delta}$ effect. Test data and analytical research demonstrated that axial load changes and $P-{\Delta}$ effect during an earthquake cause significant deterioration in the earthquake-resistance of these structural elements. It was demonstrated that inclined bars in the joint region were effective for reducing the unfavourable impact of the $P-{\Delta}$ effect and axial load changes in these structural elements.

• Steel and Composite Structures
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• 제29권5호
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• pp.635-645
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• 2018

Beam-column joints play a significant role in static and dynamic performances of reinforced concrete frame structures. This study contributes a numerical approach of topologically optimal design of carbon fiber reinforced plastics (CFRP) to retrofit existing beam-column connections with crack patterns. In recent, CFRP is used commonly in the rehabilitation and strengthening of concrete members due to the remarkable properties, such as lightweight, anti-corrosion and simplicity to execute construction. With the target to provide an optimal CFRP configuration to effectively retrofit the beam-column connection under semi-failure situation such as given cracks, extended finite element method (X-FEM) is used by combining with multi-material topology optimization (MTO) as a mechanical description approach for strong discontinuity state to mechanically model cracked structures. The well founded mathematical formulation of topology optimization problem for cracked structures by using multiple materials is described in detail in this study. In addition, moved and regularized Heaviside functions (MRHF), that have the role of a filter in multiple materials case, is also considered. The numerical example results illustrated in two cases of beam-column joints with stationary cracks verify the validity, benefit and supremacy of the proposed method.

• Structural Engineering and Mechanics
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• 제19권2호
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• pp.185-198
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• 2005

In the design of reinforced concrete beams, it is a standard practice to use the yield stress of the steel reinforcement for the evaluation of the flexural strength. However, because of strain hardening, the tensile strength of the steel reinforcement is often substantially higher than the yield stress. Thus, it is a common belief that the actual flexural strength should be higher than the theoretical flexural strength evaluated with strain hardening ignored. The possible increase in flexural strength due to strain hardening is a two-edge sword. In some cases, it may be treated as strength reserve contributing to extra safety. In other cases, it could lead to greater shear demand causing brittle shear failure of the beam or unexpected greater capacity of the beam causing violation of the strong column-weak beam design philosophy. Strain hardening may also have certain effect on the flexural ductility. In this paper, the effects of strain hardening on the post-peak flexural behaviour, particularly the flexural strength and ductility, of reinforced normal- and high-strength concrete beams are studied. The results reveal that the effects of strain hardening could be quite significant when the tension steel ratio is relatively small.

• 한국전산구조공학회논문집
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• 제12권3호
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• pp.363-370
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• 1999

본 연구에서는 철근콘크리트기둥과 철골보로 이루어진 혼합구조 접합부의 해석에 대한 유한 유소법을 이용한 해석 모델 방법을 제시하였다. 혼합구조 접합부에서 콘크리트와 강판이 접하는 접촉면은 두 접촉면 사이를 부착과 마찰의 개념으로 표현할 수 있는 주-종속 접촉 알고리즘(master-slave contact algorithm)을 이용하여 모델링하였다. 그리고, 휨응력의 지배를 받는 강관에는 비적합 모드 요소를 사용하였다. 본 연구에서의 혼합구조 특징은 보에서 기둥으로 힘의 전달을 원활히 하기 위하여 다이아프램이 사용되었고, 이러한 혼합구조 접합부 모델링 방법에 대한 타당성을 알아보기 위하여 3차원 비선형 해석을 행하여 실험결과와 비교한 결과 잘 일치하는 결과를 얻었다.

• Journal of Construction Engineering and Project Management
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• 제7권4호
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• pp.13-19
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• 2017

This study is based on the use and performance of bamboo reinforcements in construction of low-cost structures. This study investigated the physical and mechanical properties of bamboo reinforcements. Bamboo reinforced concrete beam specimens were tested with different reinforcement ratios and observed the load capacity, deflection and failure patterns. It was observed that, flexural strength of bamboo reinforced column is sufficient higher than plain cement concrete and comparable to steel reinforced concrete beams. Bamboo reinforced concrete columns with different reinforcement ratio also tested and observed the ultimate compressive strength and failure pattern. It found, all columns failed in a similar pattern due to crushing of concrete. According to cost analysis, bamboo reinforced beams and columns with moderate reinforcement ratio showed the best strength-cost ratio among plain cement concrete and steel reinforced concrete.

• 콘크리트학회논문집
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• 제22권3호
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• pp.325-333
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• 2010

이 연구에서는 시공성과 경제성이 향상되고 중진 지역에서 사용할 수 있는 새로운 프리캐스트 콘크리트 보-기둥 접합부 상세를 복합구조로 개발하고 실험을 통하여 이를 검증하였다. 이 상세는 기둥 속에 매립된 각형강관과 보U형 단부를 갖는 보 단부에 매립된 플레이트를 볼트로 결합시킬 수 있는 구조로 되어있다. 하이브리드 스틸-콘크리트 접합합부에 앞서 콘크리트가 조기에 파괴되는 것을 막기 위하여 접합부 부분에 ECC(engineered cementitious composite)를 사용하였다. 개발된 접합부 상세에 대한 성능을 검증하기 위하여 보-기둥 접합부 실험체를 계획하여 이에 대한 내진성능 실험을 실시하였다. 내부 접합부에 있어서는 접합부 횡보강근 유무와 현장타성 범위를 변수로 3개의 실험체를 제작하였다. 실험은 기둥에 일정 축력을 가한 상태에서 PC기둥 단부에 액츄에이터를 설치하여 변위제어로써 반복가력 하여 실시하였다. 실험에서 얻은 자료를 접합부 내력, 강성, 에너지 소산능력 등에 대하여 분석하였으며, 그 결과 이 연구에서 제시한 새로운 보-기둥 접합부 상세는 강재와 콘크리트 그리고 ECC 사이에서의 다른 부착 특성 때문에 구조거동에서 차이점이 관찰되었으며, 기준 실험체를 제외한 두 실험체의 경우 ECC 및 철골연결재에 의해 소성힌지를 유도할 수 있는 것으로 나타났다. 그리고 프리캐스트 접합부는 높은 일체성과 모멘트 저항 능력을 보이며 중진 지역에서 사용가능함을 보였다.

• Steel and Composite Structures
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• 제50권3호
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• pp.249-263
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• 2024

This article presents a comparative analysis of seismic behavior in steel-beam reinforced concrete column (RCS) frames versus steel and reinforced concrete frames. The study evaluates the seismic response and collapse behavior of RCS frames of varying heights through nonlinear modeling. RCS, steel, and reinforced concrete special moment frames are considered in three height categories: 5, 10, and 20 stories. Two-dimensional frames are extracted from the three-dimensional structures, and nonlinear static analyses are conducted in the OpenSEES software to evaluate seismic response in post-yield regions. Incremental dynamic analysis is then performed on models, and collapse conditions are compared using fragility curves. Research findings indicate that the seismic intensity index in steel frames is 1.35 times greater than in RCS frames and 1.14 times greater than in reinforced concrete frames. As the number of stories increases, RCS frames exhibit more favorable collapse behavior compared to reinforced concrete frames. RCS frames demonstrate stable behavior and maintain capacity at high displacement levels, with uniform drift curves and lower damage levels compared to steel and reinforced concrete frames. Steel frames show superior strength and ductility, particularly in taller structures. RCS frames outperform reinforced concrete frames, displaying improved collapse behavior and higher capacity. Incremental Dynamic Analysis results confirm satisfactory collapse capacity for RCS frames. Steel frames collapse at higher intensity levels but perform better overall. RCS frames have a higher collapse capacity than reinforced concrete frames. Fragility curves show a lower likelihood of collapse for steel structures, while RCS frames perform better with an increase in the number of stories.

• 한국강구조학회 논문집
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• 제14권1호
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• pp.121-130
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• 2002

This paper presents the tensile behavior of a Concrete-Filled Square Steel Tubular (CFT) column to H-beam welded connections. These connections were externally reinforced with T-shaped stiffeners at the junction of CFT column and beam. The tensile loading tests of eighteen tee-joint connections and finite element analysis using ANSYS were carried out. The main parameters of tests are as follows: 1) the thickness of Square Steel Tubular Column : 6 mm, 9 mm, 2) the strength ratios of tensile strength of horizontal stiffeners to tensile strength of beam flange : 70 %, 100 %, 150 %, 3) the strength ratios of shear strength of vertical stiffeners to tensile strength of beam flange : 80 %, 115 %, 160 %. The results of the tests demonstrate that overall behavior and failure modes of all the specimens are governed mainly by the horizontal stiffeners rather than the vertical stiffeners, and the vertical stiffener played only a role in transferring load introduced from beam to column.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1989년도 가을 학술발표회 논문집
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• pp.77-82
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• 1989

In this paper an experimental approach of the relocation plastic hinging zones of nine reinforced concrete exterior beam-column subassemblages under cyclic loads was tried. The main parameters of the testing program were location of the plastic hinge, difference of the special reinforcement, inclined or intermediate layers of longitudinal reinforcement, applied maximum shear stress. The conclusions presented herein are based on the limited texts conducted. Inclined or intermediate layers of longitudinal reinforcement and extra top and bottom steel in the beam over a specific legnth can be used to move the beam plastic hinging zone away from the column face. But, for the use of intermediate layers of longitudinal reinforcement, sheat reinforcement detail need further investigation.