• Structural Engineering and Mechanics
• /
• 제76권5호
• /
• pp.663-674
• /
• 2020

In this study, partially restrained beam-column moment joints in the weak-axis direction were examined using three large-scale specimens subject to cyclic loading in order to assess the seismic resistance of the joints of low-rise steel structures and to propose joint details based on the test results. The influence of different number of bolts on the moment joints was thoroughly investigated. It was found that the flexural capacity of the joints in the direction of weak axis was highly dependent on the number of high-tension bolts. In addition, even though the flexural connections subjected to cyclic loading was perfectly designed in accordance with current design codes, severe failure mode such as block shear failure could occur at beam flange. Therefore, to prevent excessive deformation at bolt holes under cyclic loading conditions, the holes in beam flange need to have larger bearing capacity than the required tensile force. In particular, if the thickness of the connecting plate is larger than that of the beam flange, the bearing capacity of the flange should be checked for structural safety.

• 한국강구조학회 논문집
• /
• 제11권2호통권39호
• /
• pp.109-116
• /
• 1999

본 논문은 관통형 고력볼트를 사용한 엔드플레이트형식 콘크리트 충전 각형 강관 기둥 H형강 보 접합부에 대한 단조가력하에서의 실험적 연구이다. 본 실험의 목적은 전회(前回)에서는 파악되지 않았던 엔드플레이트의 두께와 볼트의 배열에 대한 영향을 정확하게 평가하는데 있다. 실험의 주요변수는 엔드플레이트의 두께(12mm, 16mm)와 볼트의 배열 (EP1, EP2, EP3)이다. 변수에 따른 실험결과를 비교, 분석하였다. 1)실험체는 Bjorhovde와 EC3의 분류법에 의해 분류하였다. 2)T-stub모델에 근거한 접합부의 최대 모멘트 예측식에 의해 계산된 이론치$(_tM_u)$는 실험치$(_eM_u)$에 잘 대응하였다.

• 한국강구조학회 논문집
• /
• 제12권4호통권47호
• /
• pp.351-362
• /
• 2000

이 논문은 반복하중을 받는 관통형 고력볼트를 사용한 엔드플레이트형식 콘크리트 충전 각형강관 기둥-H형강 보 접합부의 거동에 관한 연구이다. 주요변수는 엔드플레이트의 두께(16mm, 22mm, 25mm)와 기둥의 두께(9mm, 12mm)이다. 각 변수에 대해 실험결과와 비교 분석한다. 보-기둥 접합부의 에너지 흡수능력을 구하고, 접합부 패널의 전단내력을 분석한다. 접합부 패널의 전단 내력은 von Mises 항복조건에 의한 강재의 내력과 콘크리트 충전효과를 고려한 Strut 모델을 사용한 콘크리트의 내력을 단순누가해서 구한다.

• International Journal of Safety
• /
• 제8권1호
• /
• pp.1-5
• /
• 2009

The CFRP composite has unique properties that offer high strength and stiffness, even though it has light weight. Therefore it can be used in many industrial applications. When mechanical fasteners are used for joining composites, high stress concentrations appear near the edge of holes prepared for accommodating structural bolts and rivets. This presence of high stress concentrations can be a source of damage. The aim of this work is to evaluate fracture behavior and patterns of plain woven CFRP with circular hole and repairing patch element. The maximum strength and pattern for the plain woven carbon composite specimen with the repaired circular hole were examined. From the results, we show that repairing of the CFRP composite specimen with ($\pi$) 3~5 mm of circular hole diameter results in load rising effect and the repairing is more effective as bigger hole specimen.

• Design & Manufacturing
• /
• 제14권1호
• /
• pp.42-48
• /
• 2020

Titanium alloy has been in the spotlight as a core material in high-tech industries that require high strength and light weight because it has excellent strength and corrosion resistance and strength is higher than that of steel. Therefore, in various industries, existing steel products are intended to be replaced with titanium alloys. Titanium alloys can cause cutting tool breakage during cutting, and heat generated during cutting does not dissipate, accumulates in tools and workpieces, resulting in large wear and tear on thin workpieces. In addition, since titanium alloy is a metal with high chemical activity, the wear of the tool becomes more severe when the cutting speed is high, so machining of titanium bolt through cutting is very disadvantageous in terms of productivity. Therefore, the production of bolts using titanium alloys is being produced through a forging process to improve productivity and product quality. In this paper, hot forging molding analysis was performed on bolts used for fastening automobile parts using Ti-6Al-4V alloy, which is the most commonly used titanium alloy.

• 한국구조물진단유지관리공학회 논문집
• /
• 제22권2호
• /
• pp.1-7
• /
• 2018

현수교 주 케이블은 케이블 밴드의 볼트 축력에 대한 정기적인 유지 관리가 매우 중요하다. 현수교 케이블 밴드의 볼트 축력은 시간이 경과함에 따라 케이블 소선의 크리프 현상, 볼트의 릴렉세이션, 하중 변동, 케이블 소선의 재배열 등으로 인해 축력 감소 현상이 발생하게 된다. 본 연구에서는 국내 현수 교량(SR대교)의 케이블 밴드가 시간이 경과하면서 발생하는 축력 감소 현상에 대해 그 원인 및 감소량 등에 대한 현장 측정 및 이론적 검토, 안전율 검토, 장기적인 이력 관리 등을 수행하였다. 그 결과, 케이블 밴드 볼트 축력 감소는 주 케이블 소선에 사용된 아연 도금층의 소성 변형에 크게 영향받는 것을 확인하였으며, 이에 대한 이론적 체계 및 장기 이력 관리에 대한 적용성을 확립하였다.

• 복합신소재구조학회 논문집
• /
• 제6권3호
• /
• pp.32-40
• /
• 2015

The torque shear high strength bolt is clamped normally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the required tension, as it considerably fluctuates due to torque coefficient dependent on lubricant affected temperature. In this study, the clamping tests of torque shear bolts were conducted independently at indoor conditions and at construction site conditions. During last six years, temperature of candidated site conditions was recorded from $-11^{\circ}C$ to $34^{\circ}C$. The indoor temperature condition was ranged from $-10^{\circ}C$ to $50^{\circ}C$ at each $10^{\circ}C$ interval. As for site conditions, the clamping force was reached in the range from 159 to 210 kN and the torque value was from 405 to $556 N{\cdot}m$. The range of torque coefficient at indoor conditions was analyzed from 0.126 to 0.158 while tensions were indicated from 179 to 192 kN. The torque coefficient at site conditions was ranged from 0.118 to 0.152. Based on this test, the variable trends of torque coefficient, tension subjected temperature can be taken by statistic regressive analysis. The variable of torque coefficient under the indoor conditions is $0.13%/^{\circ}C$ while it reaches $2.73%/^{\circ}C$ at actual site conditions. When the indoor trends and site conditions is combined, the modified variable of torque coefficient can be expected as $0.2%/^{\circ}C$. and the modified variable of tension can be determined as $0.18%/^{\circ}C$.

• Structural Engineering and Mechanics
• /
• 제88권2호
• /
• pp.129-140
• /
• 2023

To increase the stiffness and strength of a reinforced concrete shear wall, steel plates are bolted to the sides of the wall. The general behavior of a composite concrete-steel shear wall is dependent on the buckling of the steel plates that should be prevented. In this paper, the unilateral buckling of steel plates of a composite shear wall is studied using the Rayleigh-Ritz method. To model the unilateral buckling of steel plate, the restraining concrete wall is described as an elastic foundation with high stiffness in compression and zero stiffness in tension. To consider the effect of bolt connections on the plate's buckling, a constrained optimization problem is solved by using Lagrange multipliers method. This process is used to obtain the critical elastic local buckling coefficients of unilaterally-restrained steel plates with various numbers of bolts, subjected to pure compression, bending and shear loading, and the interaction between them. Using these results, the spacing between shear bolts in composite steel plate shear walls is estimated and compared with the results of the AISC seismic provisions (2016). The results show that the AISC seismic provisions(2016) are overly conservative in obtaining the spacing between shear bolts.

• 한국강구조학회 논문집
• /
• 제27권2호
• /
• pp.251-260
• /
• 2015

단부판 접합부는 다양한 형태로 보-기둥 모멘트 접합부에 적용되고 있다. 이러한 단부판 접합부는 단부판의 두께 및 길이, 고장력 볼트의 개수 및 직경, 고장력볼트의 게이지 거리, 고장력볼트의 지레작용력, 용접부의 치수 및 길이 등에 따라서 상이한 거동특성, 강성 및 강도, 에너지소산능력의 변화를 나타낸다. 따라서 이 연구는 단부판의 두께 변화에 따른 인장측에 체결된 고장력볼트의 지레작용력 및 축방향 인장강성을 파악하고, 단부판의 거동특성에 영향을 미치는 이러한 변수들을 예측하기 위한 해석모델을 제안하기 위하여 진행하였다. 이를 위하여 이 연구에서는 단부판의 두께만을 변수로 선택하여 비보강 확장단부판 접합부에 대한 3차원 비선형 유한요소해석을 수행하였다.

• Steel and Composite Structures
• /
• 제44권1호
• /
• pp.1-15
• /
• 2022

The weld quality has always been an important factor affecting the development of exposed CFT column-base joint. In this paper, a new type of exposed RCFST column-base joint is proposed, in which the high strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens, the varying axial force ratio (0, 0.25 and 0.5), were tested under cyclic loadings. In addition, the bending moment capacity, energy dissipation capacity and deformation capacity of column-base joints were clarified. The experimental results indicated that the axial force ratio increases the stiffness and the bending moment and improves the energy dissipation capacity of column-base joints. This is because a large axial force can limit the slip between steel tubular and infilled concrete effectively. The specimens show stable hysteresis behavior.