• Structural Engineering and Mechanics
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• 제12권2호
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• pp.157-168
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• 2001

In this paper, experimental investigation into the behavior of reinforced concrete (RC) columns tested under large lateral displacement with four different types of loading arrangements is presented. Each loading arrangement has a different system for controlling the consistency of the loading condition. One of the loading arrangements used three units of link mechanism to control the parallelism of the top and bottom stub of column during testing, and the remaining employed eight hydraulic jacks for the same purpose. The loading systems condition used in this investigation were similar to the actual case in a moment-resisting frame where the tested column was displaced in a double curvature. Ten model column specimens, divided into four series were prepared. Two columns were tested monotonically until collapse, and unless failure took place at an earlier stage of loading, the remaining eight columns were tested under cyclic loading. Test results indicated that the proposed system to keep the top and bottom stubs parallel during testing performed well.

• Structural Engineering and Mechanics
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• 제63권3호
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• pp.385-400
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• 2017

This paper presents an experimental study on the behavior of axially-loaded steel RHS (rectangular hollow section) compression members that are partially reinforced along their lengths with welded steel plates. 28 slender column tests were carried out to investigate the effects of the slenderness ratio of the unreinforced member and the ratio of the reinforced length of the member to its entire length. In addition to the slender column tests, 14 stub-column tests were conducted to determine the basic mechanical properties of the test specimens under uniform compression. Test results show that both the compressive strength and stiffness of an RHS member can be increased significantly compared to its unreinforced counterpart even when only the central quarter of the member is reinforced. Based on the limited test data, it can be concluded that partial reinforcement is, in general, more effective in members with larger slenderness ratios. A simple design expression is also proposed to predict the compressive strength of RHS columns partially reinforced along their length with welded steel plates by modifying the provisions of AISC 360-10 to account for the partial reinforcement.

• Structural Engineering and Mechanics
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• 제77권6호
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• pp.745-751
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• 2021

Concrete filled double skin tubular members (CFDST) consist of double concentric circular or square steel tubes with concrete filled between the two steel tubes. The CFDST members, having a hollow section inside the internal tube, are generally lighter than ordinary concrete filled steel tubular members (CFT) which have a solid cross-section. Therefore, when the CFDST members are applied to bridge piers, reduction of seismic action can be expected. The present study aims to investigate, experimentally, the behavior of CFDST stub columns with double concentric square steel tubes filled with concrete (SS-CFDST) when working under centric compression. Two test parameters, namely, inner-to-outer width ratio and outer square steel tube's width-to-thickness were selected and outer steel tube's width-to-thickness ratio ranging from 70 to 160 were considered. In the results, shear failure of the concrete fill and local buckling of the double skin tubes having largest inner-to-outer width ratio were observed. A method to predict axial loading capacity of SS-CFDST is also proposed. In addition, the load capacity in the axial direction of stub column test on SS-CFDST is compared with that of double circular CFDST. Finally, the biaxial stress behavior of both steel tubes under plane stress is discussed.

• Steel and Composite Structures
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• 제16권2호
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• pp.221-231
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• 2014

The purpose of this study was to evaluate the cyclic behavior of steel column-tree moment connections used in steel moment resisting frames. These connections are composed of shop-welded stub beam-to-column connection and field bolted beam-to-beam splice. In this study, the effects of beam splice length on the seismic performance of column-tree connections were experimentally investigated. The change of the beam splice location alters the bending moment and shear force at the splice, and this may affect the seismic performance of column-tree connections. Three full-scale test specimens of column-tree connections with the splice lengths of 900 mm, 1,100 mm, and 1,300 mm were fabricated and tested. The splice lengths were roughly 1/6, 1/7, 1/8 of the beam span length of 7,500 mm, respectively. The test results showed that all the specimens successfully developed ductile behavior without brittle fracture until 5% radians story drift angle. The maximum moment resisting capacity of the specimens showed little differences. The specimen with the splice length of 1,300 mm showed better bolt slip resistance than the other specimens due to the smallest bending moment at the beam splice.

• Structural Engineering and Mechanics
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• 제88권3호
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• pp.287-299
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• 2023

This article describes experimental and numerical analyses of eccentrically loaded over the axially loaded circular concrete filled double-skinned steel tubular (CFDST) short columns. Tests on circular CFDST short columns under eccentric and concentric loading were conducted to assess their responses to the frequent intensity of 5-30 mm at the interval of each 5 mm eccentric loading conditions with constant cross-sectional proportions and width-to-thickness ratios of the outside and internal tubes. The non-linear finite-element analysis of circular CFDST short columns of eccentrically loaded over the axially loaded was performed using the ABAQUS to predict the structural behavior and compare the concentric loading capacity over the various eccentric loading conditions. The comparison outcomes show that the axial compressive strength of the circular CDFST short columns was 2.38-32.86%, lesser than the concentrically loaded short column with the inner circular section. Also, the influence of computer simulation employed is more efficient in forecasting the experimentally examined performance of circular CFDST stub columns.

• 한국강구조학회 논문집
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• 제26권5호
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• pp.453-461
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• 2014

본 연구에서는 건축구조용 고성능강 HSA800의 건축구조부재로의 적용을 위한 연구로써, 용접 제작된 각형강관 및 H형강에 대해 단주편심압축 실험을 바탕으로 해석모델을 이용한 검증이 이루어졌다. 특히, 고성능강 조립단주의 유한요소해석을 이용한 변수연구와 P-M 상관관계로부터 현행 기준의 적용여부를 평가하고자 하였으며, 폭두께비와 축력비를 주요변수로 두었다. 변수모델의 P-M상관도 분석결과, 압축력에 대한 비세장단면은 모두 현행기준의 요구에서 크게 상회하는 결과를 얻었고 축력비가 낮을수록 휨강도비에 충분한 여유를 갖는 것을 확인하였다. 압축력에 대한 세장판 단면을 갖는 각형강관의 경우, 현행기준의 요구에 못 미치는 결과를 보였다.

• 한국강구조학회 논문집
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• 제28권1호
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• pp.53-64
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• 2016

상 하부 스플릿 티 접합부는 보-기둥 모멘트 접합부의 한 형태로 T-stub 플랜지의 두께, 고장력볼트의 게이지 거리, 고장력볼트의 개수, 고장력볼트의 직경 등의 변화에 따라서 상이한 거동특성을 나타낸다. 상 하부 스플릿 티 접합부는 일반적으로 상 하부에 체결된 T-stub이 휨모멘트를 지지하고 전단탭이 전단력을 지지하는 것으로 이상화하여 설계되고 있다. 그러나 중 저층 강구조물에 상 하부 스플릿 티 접합부가 적용되면 보 부재의 규격이 작아지므로 보 웨브에 전단탭을 설치할 수 없는 경우가 발생할 수 있다. 이 연구는 이와 같이 보 웨브에 전단탭 설치가 어려운 기하학적 형상을 갖는 상 하부 스플릿 티 접합부가 충분한 전단력 지지능력을 발현하도록 하는 접합부상세를 제안하기 위하여 진행하였다. 이를 위하여 상 하부 스플릿 티 접합부에 대한 실험체를 제작하여 실물대 실험을 수행하였다.

• 한국강구조학회 논문집
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• 제26권4호
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• pp.289-297
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• 2014

본 연구에서는 고강도강재(HSA800)의 단주 편심압축실험을 통해 휨-압축 부재의 강도를 평가하였다. 편심압축실험은 축력비에 따라 휨-압축의 조합력을 받는 부재의 P-M 상관관계를 알아보기 위해 HSA800강재의 각형강관과 H형강을 대상으로 실험을 수행하였으며, 가력 편심거리를 조정하여 다양한 P-M 조합에 대해 강도평가 실험을 수행하였다. 실험결과 실험최대 평균응력은 국부좌굴에 의한 최대내력이 결정된 실험체에 대해서는 판폭두께비가 증가함에 따라 감소하는 경향을 보였다. 발현강도의 여유는 축력이 낮을수록 상대적으로 휨강도에 대해 큰 마진을 보이고 있었고, 실험체 모두 현행 설계기준의 P-M 상관관계를 안전측으로 충족하였다.

• Computers and Concrete
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• 제9권4호
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• pp.257-273
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• 2012

Based on the heterogeneous characterization of concrete at mesoscopic level, Realistic Failure Process Analysis ($RFPA^{3D}$) code is used to simulate the failure process of concrete-filled tubular (CFT) stub columns. The results obtained from the numerical simulations are firstly verified against the existing experimental results. An extensive parametric study is conducted to investigate the effects of different concrete strength on the behaviour and load-bearing capacity of the CFT stub columns. The strength of concrete considered in this study ranges from 30 to 110 MPa. Both the load-bearing capacity and load-displacement curves of CFT columns are evaluated. In particular, the crack propagation during the deformation and failure processes of the columns is predicted and the associated mechanisms related to the increased load-bearing capacity of the columns are clarified. The numerical results indicate that there are two mechanisms controlling the failure of the CFT columns. For the CFT columns with the lower concrete strength, they damage when the steel tube yields at first. By contrast, for the columns with high concrete strength it is the damage of concrete that controls the overall loading capacity of the CFT columns. The simulation results also demonstrate that $RFPA^{3D}$ is not only a useful and effective tool to simulate the concrete-filled steel tubular columns, but also a valuable reference for the practice of engineering design.

• 한국강구조학회 논문집
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• 제24권1호
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• pp.23-34
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• 2012

본 연구에서는 인장강도 800MPa급 고강도강재(HSA800)의 단주 중심압축실험과 편심압축실험을 통해 균등압축과 휨-압축 부재의 강도를 평가하여 현행 강구조기준(KBC2009, AISC2005)의 적용성 여부를 검토하였다. 또한 잔류응력의 계측을 통하여 강재 항복강도와 잔류응력과의 상관성 여부도 검토하였다. 고강도강재와 일반강재의 국부좌굴 거동 차이의 여부를 확인하기 위하여 중심압축실험에 SM490 강재로 제작된 비교실험체도 포함시켰다. 강도로 무차원화한 판폭두께비와 판 단부의 지지조건을 주요변수로 하여 실험을 실시하였다. 편심압축실험은 HSA800 강재만을 대상으로 하였으며, 휨-압축의 조합력을 받는 부재의 P-M 상관관계를 알아보기 위해 가력 편심거리를 조정하여 다양한 P-M 조합에 대해 강도평가 실험을 수행하였다. 잔류응력은 중심압축실험에 사용된 H형단면 실험체를 대상으로 비파괴실험법인 압입법에 의해 가력 이전에 그 크기와 분포를 측정하였다. 실험결과 중심압축을 받는 모든 HSA800 단주는 판 단부의 지지조건 및 판폭두께비 조건에 따른 현행 강구조기준의 설계강도를 충분히 발휘하였다. 편심압축을 받는 실험체 역시 현행 설계기준의 P-M 상관관계를 충분히 안전측으로 충족하였다. 본 연구에서도 잔류응력의 크기는 강재의 항복강도와 무관하다는 선행연구결과와 합치하는 잔류응력 측정값이 얻어졌다.