For fast-built and safe precast concrete (PC) construction, the dry mechanical splicing method is a critical technique that enables a self-sustaining system (SSS) during construction with no temporary support and minimizes onsite jobs. However, due to limited experimental evidence, traditional wet splicing methods are still dominantly adopted in the domestic precast industry. For PC beam-column connections, the current design code requires achieving emulative connection performances and corresponding structural integrity to be comparable with typical reinforced concrete (RC) systems with monolithic connections. To this end, this study conducted the standard material tests on mechanical splices to check their satisfactory performance as the Type 2 mechanical splice specified in the ACI 318 code. Two PC beam-column connection specimens with dry mechanical splices and an RC control specimen as the special moment frame were subsequently fabricated and tested under lateral reversed cyclic loadings. Test results showed that the seismic performances of all the PC specimens were fully comparable to the RC specimen in terms of strength, stiffness, energy dissipation, drift capacity, and failure mode, and their hysteresis responses showed a mitigated pinching effect compared to the control RC specimen. The seismic performances of the PC and RC specimens were evaluated quantitatively based on the ACI 374 report, and it appeared that all the test specimens fully satisfied the seismic performance criteria as a code-compliant special moment frame system.

This study presents a dry precast concrete (PC) beam-column connection, and its target seismic performance level is set to be emulative to the reinforced concrete (RC) intermediate moment resisting frame system specified in ACI 318 and ASCE 7. The key features include self-sustaining ability during construction with the dry mechanical splicing method, enabling emulative connection performances and better constructability. Test specimens with code-compliant seismic details were fabricated and tested under reversed cyclic loading, which included a PC beam-column connection specimen with dry connections and an RC control specimen. The test results showed that all the specimens failed in a similar failure mode due to plastic deformations in beam members, while the hysteretic response curve of the PC specimen showed comparable and emulative performances compared to the RC specimen. Seismic performance evaluation was quantitatively addressed, and on this basis, it confirmed that the presented system can fully satisfy all the required performance for the intermediate RC moment resisting frame.

The column-tree type steel beam-column connections are commonly used in East Asian countries, including Korea. The welding detail between the stub beam and column is similar to the WUF-W connection; thus, it can be expected to have sufficient seismic performance. However, previous experimental studies indicate that premature slip occurs at the friction joints between the stub and link beams. In this study, for the accurate seismic performance evaluation of column-tree type moment connections, a moment-slip model was proposed by investigating the previous test results. As a result, it was found that the initial slip occurred at about 25% of the design slip moment strength, and the amount of slip was about 0.15%. Also, by comparing the analysis results from models with and without the slip element, the influence of slip on the performance of overall beam-column connections was examined. As the panel zone became weaker, the contribution of slip on overall deformation became greater, and the shear demand for the panel zone was reduced.

우리나라는 지진으로부터 안전한 국가라는 인식이 형성되었으나 최근 경주와 포항 지진에 의해 발생된 구조물 피해로 구조물 안전성 확보를 위한 관심이 증가하고 있다. 국내 중저층 건축물에 다수 적용되고 있는 철골 모멘트 골조는 기본적인 내진성능을 보유하고 있지만 보-기둥 접합부의 소성변형으로 인한 취성파괴로 다양한 문제를 발생시킨다. 최근에는 이러한 문제를 해결하기 위해 구조물에 상온에서 잔류변형으로부터 원형복원이 가능한 초탄성 형상기억합금의 활용에 관한 연구가 진행되고 있다. 따라서 본 연구에서는 소성변형이 집중되는 보 플랜지 부재에 초탄성 형상기억합금 보강판을 활용한 보–기둥 접합부에 대하여 실험을 통한 실질적인 내진성능을 평가하고자 한다.

As buildings are becoming larger, demand for large-scale composite columns for heavy load is increasing. Welded built-up CFT column (ACT Column I) previously developed by authors of this study is structurally stable and economical. Characteristic of welded built-up CFT column is that there is a limitation of cross-sectional size and application of external diaphragm connection to ensure continuity of rib. Then, composite mega column (ACT Column II) was developed to improve limit of cross-sectional size. Composite mega column has a closed cross section like welded built-up CFT column, but thick plate is inserted between cold-formed steel to expand cross section size. However, when external diaphragm connection is applied to composite mega column, amount of steel is increased greatly and interference with finishing material occurs. In this study, internal diaphragm connection is applied through characteristic of composite mega column to which beam flange or stiffener can be attached to plate. In order to analyze this, simple tensile experiment of composite mega column connection with T-shaped stiffener was performed.

Unlike column-to-beam connections in reinforced concrete frames, column-to-beam connections are generally of the same type. Vertical load (D.L + L.L) and horizontal load (wind load, seismic load) are not the same in the upper and lower flange stress history. In the case of beams bonded to synthetic CFT columns, the tensile force is transmitted through the steel pipe column, and the compressive force is transmitted to the filled concrete, so the seismic performance is excellent even if the column has a relatively thin cross section. Also, in case of beam the composite CFT column, tensile force is taken by the steel pipe column, and the compressive force is caught by the inner concrete, and the shape of the column joint can be changed. In this study, the stress distribution of buildings is investigated according to the size and characteristics of the building, and the load history of the upper and lower flanges according to the building type is checked to show the structural possibility of the Asymmetric Diaphragms joint.

As buildings are becoming larger, demand for mega-sized composite columns (over 1-meter diameter) is increased. We have developed and commercialized welded built-up CFT column (ACT Column I) since 2005 which are structurally stable and economical using cold-formed steel with rib. However, there has a limit in size of cross section (618˟618mm) by a fabrication facilities. And due to characteristics of closed cross section, there has a limit to construction of connection of moment frame. Composite mega column (ACT Column II) has same concept of forming closed cross section. But in order to enlarge cross sectional size, thick plate is inserted between cold-formed steels. Since composite mega column can control thickness and width of thick plate, steel or composite beams can be directly attached to the connection. In this study, we propose strength formula of composite mega column to beam connections with T-shaped stiffener as internal diaphragm and verified through finite element analysis and simple tensile experiment.

Behavior of RC(Reinforced-concrete) beam-column connections has been subjected to the earthquake loading has been determined by shear and attachment mechanism. However, since the shear and attachment are very fragile for cycle loadings. Through occurring plastic hinges at the beam, the column and the connection should remain elastic condition and the beam should dissipate the energy from the earthquake. This study was investigate on the seismic performance of 6 RC beam - column connections built with the high strength reinforcements (700MPa) based on design and detailing requirements in the ACI 318-05 Provision and KCI-07 appendix Ⅱ. This is aimed to evaluate the effect of the high-strength reinforcements as used the beam-column connection members. The main comparisons were the seismic performance of the connections affect the seismic performance in terms of strength, stiffness and ductility, joint shear stress-strain. A total of 6 beam-column specimens were built with a 1/2 scale and subjected to the cyclic loadings. Main design considerations were the area of the longitudinal reinforcements of the beam and details of the beam-column joint designed based on the seismic code. Cyclic test results are given and recommendations for the usage of high strength reinforcements for the seismic design is provided.

In this study, the seismic performance of connections between filled composite beam (CG beams) and forming angle composite (FAC) column was experimentally evaluated. First, the bending tests were conducted on two CG beams and the axial tests were conducted on two FAC columns. Then, based on these preliminary test results, the cyclic loading test were performed on two interior connections between CG beam and FAC column. The main difference of two specimens is the plate shape of the CG beam. The test results showed that both specimens achieved the maximum story drift capacity over 0.04 radian which is required for special moment frame.

The concrete-filled tube (CFT) column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. Its Solution, 2 members of ㄷchennel in which Internal diaphragm is installed were welded beforehand and the method of making Rectangular Steel Tube was proposed. According to upside and downside junction shape, Internal diaphragm suggested as symmetric specimen and asymmetric specimen. The upper and lower diaphragm of the Symmetric specimen used the same horizontal and The upper diaphragm of the Asymmetric specimen used the horizontal plate and the lower diaphragm used the vertically plate. In this research, 4 T-shape column to beam steps connections were tested with cyclic loading experiment in order to evaluate the structural capability of the offered connection. Symmetric specimens be a failure in 0.03rad from beam flange. And Asymmetric specimens be a failure in 0.05rad from column interface. The comparison results of All specimens shown similar to energy absorption capacity in 0.02rad.

The construction of a moment connection for a rectangular hollow section (RHS) column and a H-shaped beam is difficult because the RHS is a closed section. When a inner diaphragm is used for such a connection, in general, it is installed after cutting the HSS columns, which results in increased construction work. This paper suggests a new fabrication method to overcome such problems: An inner diaphragm is welded to inside a C-shaped section first, and then a column is fabricated by welding two C-shaped sections. This fabrication method is superior to a classic method in terms of constructibility. An experimental and a numerical study using Ansys 9.0 were performed in order to compare the strength of connections with respect to the presence of concrete, the corner shape of diaphragm, and the axis of loading. The experimental results including initial stiffness and ultimate loads are reported and the analytical results including load transfer mechanism, degree of stress concentration, and strain distribution are also reported.

This study aimed at construction of text and graphic database for moment-rotation curves of partially restrained composite beam-to-column connections. key words The M-θ data or figures under monotonic or cyclic tests are made as text files. Also, Eurocode 3 classification is added to the M-θ curve to verify as semi-rigid connections. For structural analysis, linear rotational stiffeness or nonlinear M-θ curves are transformed three-parameter power model. Although this database has some limitation, it will be used for further PRCC researches and tests.

프리캐스트 콘크리트 골조에서 실물크기의 보-기둥 접합부 실험체 5개를 대상으로 반복가력 실험을 수행하였다. 지진하중을 받는 골조를 대상으로 1개의 일체식 실험체와 4개의 프리캐스트 실험체를 포함하여 5개의 1/2스케일의 내부 보-기둥 접합부를 대상으로 하였다.주요 변수는 보의 구조적 연속성을 확보하기 위한 접합부의 형태와 접합부의 특별한 보강형태(섬유콘크리트와 횡보강근)로 하였다. 실험체는 강기둥-약보 개념에 따라 설계하였다. 보 철근은 접합부에 큰 비탄성 전단력이 작용할 경우 보에 소성힌지가 발생하도록 계획하였다. 접합부의 성능평가는 접합부의 강도, 강성, 에너지 소산능력과 층간변위비로 평가하였다. 실험결과 실험체의 파괴는 보의 소성힌지부에서 파괴되었다. 보-기둥 접합부의 성능은 대체적으로 우수한 것으로 나타났다. 접합부의 강도는 일체식 RC 구조의 비해 1.15배 정도 향상되었다. 층간변위 3.5%때의 강도에서 실험체는 ECC의 인장변형능력과 철골연결재의 항복에 의해 연성거동 하였다.

PPS(Post-tensioned Precast concrete System)공법은 U자형 PC로 제작된 넓은 보와 PC또는 현장 타설 콘크리트로 제작한 기둥으로 구성되며, PC보와 기둥의 일체성 확보를 위하여 프리스트레스를 도입하였다. 본 연구에서는 포스트텐션을 도입한 넓은 보-기둥 접합부의 구조적 특성을 규명하고, 다양한 변수해석이 가능하기 위한 자료를 제공하고자 유한요소해석 프로그램인 ANSYS을 사용하여 비선형 해석을 수행하였다 콘크리트에 대한 해석요소는 8개의 절점을 가지며 각 절점이 3개의 자유도(X, Y, Z축에 대한 병진 변위)를 갖는 Solid 65요소를 사용하였다. Solid 65요소에서 전단전달계수(Shear-Transfer factor)는 실험값에 근사적으로 해석값을 맞추기 위한 영향 계수값으로 균열이 발생하는 위치에 대한 전단강도의 감소를 반영한다. 그 결과, 본 실험체에 대한 해석에서는 열려진 전단전달계수 0.125와 닫혀진 전달계수 0.85에 기초하여 해석한 결과 닫혀진 전단전달계수는 0.85에서 열려진 전단전달계수에서는 0.2일때 가장 실험값에 근사한 해석치를 보였다.

본 논문에서는 철근콘크리트 모멘트 골조의 보-기둥 접합부에 대한 비탄성 회전 능력의 성능을 조사한 연구 결과를 하고 있다. 총 91개의 보-기둥 접합부 실험체에 대해 상세히 조사되었으며, 그 중 28개의 실험체는 ACI 318-02의 상세 요구에 기초하여 특수 모멘트 골조 접합부로서 분류되었다. AISC-97 내진 기준에서 철골 모멘트 골조 접합부를 위해 정의된 허용기준이 분류된 철근콘크리트 모멘트 골조의 접합부에 대해 평가하기 위해서 사용되었다. 특수 모멘트 골조 접합부에 대한 설계 상세를 만족하는 28개의 실험체 중 27개의 특수 모멘트 골조 접합부가 충분한 강도를 가지고 있었으며, 급격한 강도 감소 없이 0.03 rad.의 소성 회전에 대해 연성 거동을 발휘할 수 있음을 보여 주었다. 접합부의 전단 강도, 기둥과 보에 대한 휨 강도 비율, 접합부내에서의 횡방향 철근비 등에 대한 제한이 보-기둥 접합부의 만족스런 내진 성능을 보여주는데 중요한 역할을 하였다.

본 논문에서는 철골 각형강관단면(RHS) 기둥-보 접합부에서 웨브의 모멘트 전달효율을 평가하였다. 먼저, 5개의 철골보접합부에 대한 비선형 유한요소해석을 수행하였다. 이들은 접합부 상세가 다르게 설계되었고, 따라서 휨저항 성능이 각기 다르다. 해석결과 RHS 기둥을 가진 모델은 기둥 플랜지의 면외변형 때문에 WF(Wide Flange) 기둥을 가진 모델에 비해 모멘트 전달효율이 저하함을 보였다. 스캘럽(WAH)과 얇은 강관기둥 두께도 모멘트 전달효율의 저하를 가져오는 원인으로서, 결과적으로 보-기둥 접합부의 파단을 초래할 가능성이 크다. 해석과 이전의 실험결과를 기초로 하면, 응력집중은 모멘트 전달효율과 반비례하고, 접합부의 변형능력은 모멘트 전달효율의 저하에 따라 감소하는 것을 알 수 있다. 더 나아가서 바닥슬래브가 있는 합성보 접합부에 대한 유한요소해석결과는 중립축이 상부플랜지 방향으로 상승함으로써 모멘트 전달효율이 저하했고, 이러한 영향은 접합부의 조기 취성파단을 초래하는 것을 보였다.

Frame is one of the most commonly used structural systems for the resistance of applied loads. Many researchers have recently conducted their studies to investigate the effect of several parameters such as the connection flexibility, boundary condition of each support, beam-to-column stiffness ratio. These parameters play important roles on the characteristic behavior of frames. A simplified spring model is proposed to obtain the story drifts of frames with various beam-to-column connection stiffnesses in this research. A point bracing system with adequate spring stiffness is also suggested to establish the relationship between the applied load and the resisting translational spring stiffness within the limit state of story drift.

1994년 Northridge 지진과 1995년 Kobe 지진에서 많은 철골구조물의 보-기둥 접합부에 발생한 규열은 내진성능이 우수한 것으로 알려진 모멘트 저항 철골골조의 내진성능 개선에 대한 연구필요성을 제시하였다 일반적으로 모멘트 저항 골조가 강한 지진을 받을 때 보-기둥 접합부는 강도의 저하없이 소성 회전변형능력이 0.015이면 만족할 수 있다고 한다. 본 연구의 목적은 강한 지진하중에서도 철골구조의 보-기둥 접합부에서 용접부의 균열이 방지되고 연성적으로 충분한 에너지를 흡수하고 소산할 수 있는 접합부의 형태를 제안하고 그 거동을 조사하는 것이다 본 연구에서는 접합부의 형태를 제안하였으며 실험을 통하여 그 거동을 분석하였다 제안된 접합부 시험체에 대한 실험결과는 용접부에 균열이 발생하지 않았으며충분한 변형능력을 나타냈다.

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.