• 대한기계학회논문집A
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• 제31권2호
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• pp.166-173
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• 2007

Fatigue fracture behavior of a hybrid bolted joint was evaluated in comparison to the case of static fracture. Two kinds of specimens were fabricated for the mechanical tests; a hybrid bolted joint specimen for the shear test and a hybrid joint part specimen applied in the real tilting car body for the bending test. Characteristic fracture behaviors of those specimens under cyclic toads were obviously different from the case under static loads. For the hybrid bolted joint specimen, static shear loading caused the fracture of the bolt body itself in a pure shear mode, whereas cyclic shear loading brought about the fracture at the site of local tensile stress concentration. For the hybrid joint part specimen, static bend loading caused the shear deformation and fracture in the honeycomb core region, while cyclic bend loading did the delamination along the interface between composite skin and honeycomb core layers as well as the fracture of welded joint part. Experimental results obtained by static and fatigue tests were reflected in modifications of design parameters of the hybrid joint structure in the real tilting car body.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.5290-5298
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• 2013

본 논문에서는 프리캐스트 방식으로 제작 가능한 격자형 강합성 바닥판의 이음부에 기계식 연결방식을 적용하고자 콘크리트 전단키와 고장력볼트로 구성되는 이음부에 대해 Push-out 시험으로 전단내력을 구하였으며, 이를 전단마찰 이론에 근거한 이론식 및 설계식과 비교함으로써 전단내력을 평가하였다. 분석결과에 따르면, 이음부 접합면을 에폭시로 부착한 경우가 전단키를 강판으로 보강한 경우 보다 약 10% 정도 더 큰 전단내력을 갖는 것으로 나타났으나, 실험체간 전단내력의 편차는 전단키를 강판으로 보강한 경우가 더 작게 나타났다. 실험결과를 계산식 및 설계식과 비교한 결과, 기존 설계식으로 안전하게 설계될 수 있음을 알 수 있었다. 그러나, ACI-318에 의할 경우 이음부 전단내력이 과소평가되기 때문에 LRFD에서 제시된 설계식의 적용이 더 적당한 것으로 분석되었다.

• 대한금속재료학회지
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• 제47권4호
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• pp.261-266
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• 2009

The mechanical and electrical properties of ball grid array (BGA) solder joints were measured, consisting of Sn-3.5Ag, with organic solderability preservative (OSP)-finished Cu pads and Electroless Nickel/Immersion Gold (ENIG) surface finishes. The mechanical properties were measured by die shear test. When ENIG PCB was upper joint and OSP PCB was lower joint, the highest shear force showed at the third reflow. When OSP PCB was upper joint and ENIG PCB was lower joint, the highest shear force showed at the forth reflow. For both joints, after the die shear results reached the highest shear force, shear force decreased as a function of increasing reflow number. Electrical property of the solder joint decreased with the function of increasing reflow number. The scanning electron microscope results show that the IMC thickness at the bonding interface gets thicker while the number of reflow increases.

• 한국지반공학회논문집
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• 제16권6호
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• pp.35-41
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• 2000

Residual stress is defined as a minimum stress with a large displacement of specimens and the residual stress after peak shear stress appears with displacement volume but there is no provision to select the residual stress. In the previous study, residual stress was recorded when the change of shear load is small in the condition of the strain more than 15%. But, in this study, hyperbolic function((No Abstract.see full/text), b=experimental constant) of soil test is adapted to joint of rock and the propriety is investigated. In a landslide and landsliding of artificial slope, wedge failure of tunnel with a large displacement, tests are simulated from peak stress to residual stress for safety analysis. But now. direct shear stress and triaxial compressive tests are usually performed to find out characteristics of shear stress about joint. Although these tests get a small displacement, that data of peak stress and residual stress are used for safety analysis. In this study, we tried to determine failure criteria for joints of rock using ring shear test machine. The residual stress following shear behavior was determined by the result of ring shear test and direct shear test. In conclusion, after comparing the results of the two test, we found that cohesion(c) and internal friction angle(ø) of ring shear test are 30% and 22% respectively of those of the direct shear test.

• 터널과지하공간
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• 제7권1호
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• pp.20-30
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• 1997

A discrete joint finite element with joint surface degradation was developed to investigate the shear behavior of rough rock joint. Isoparametric formulation was used for facilitating the implementation of the element in existing Finite Element Codes. The elasto-plastic joint deformation model with the discontinuity constitutive law proposed by Plesha was applied to the element. The reliability of the developed finite element code was successfully testified through numerical direct shear tests conducted under both constant normal stress and constant normal displacement conditions. The result of the numerical direct shear test showed that the code can capture characteristic deformation features envisaged in the direct shear test of rough rock joint.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.303-308
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• 2000

The design of column joint is an important part of earthquake resistant design of reinforced concrete moment resisting frames. Beam column joints must provide sufficient stiffness and strength to resist and sustain the loads induced by adjacent beams and columns. This paper investigates the difference of the current design codes which provide a different approach for the design of beam column joint in seismic zone. The model provided by Hitoshi Shiohara(1998) is reviewed in this paper, which provides a good relationship between moment and shear action of interior beam column joint and a role shear reinforcement according to their position.

• 콘크리트학회지
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• 제8권4호
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• pp.171-179
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• 1996

PC판넬 조립식 구조의 수직.수평접합부의 유용한 접합형태에 따라 접합부 전단내력을 상승시킬 수 있는 접합부 설계의 기본 형태를 제시하는데 연구의 목적이 있다. 시험체는 수직접합부의 경우 전단키의 개수 및 보강철물의 종류에 변수를 주고 수평접합부의 경우에는 전단키의 갯수 및 가력방향에 변수를 주어 총 22개의 시험체를 제작하여 실험하였다. 결론적으로 수직접합부의 경우, 수평보강철물이 있는 시험체는 기존의 다른 실험결과와 마찬가지로 수평보강철물이 없는 시험체에 비하여 연성이 크게 나타났다. EH한 와이어로프와 원형철근 두 종류의 보강철물을 사용하여 실험한 결과 와이어 로프를 사용한 시험체는 원형철근을 사용한 시험체와 최대내력 및 전단강성 등 전체적인 구조거동이 거의 비슷하게 나타났다.

• 터널과지하공간
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• 제23권5호
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• pp.401-412
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• 2013

전단거동에 의한 절리면의 거칠기 변화가 전단강도에 미치는 영향을 조사하기 위하여 절리면 강도가 상이한 편마암, 화강암 및 셰일 시료를 이용하여 순차적 다단계 전단시험을 수행하였다. 시험단계별로 절리면 프로파일의 고도를 측정하여 거칠기 계수를 산정하고 미세 거칠기 빈도 변화를 조사하였다. 거칠기 감쇠에 대한 최적의 거칠기 계수를 산정하여 반복된 전단거동에 의한 순차적 거칠기 감쇠특성을 고찰하였다. 전단강도식을 산정하여 점착력과 마찰각의 차별적 변화양상을 도출하였으며, 표면 거칠기의 마모, 파쇄 및 재형성에 의한 미세 거칠기 빈도변화를 조사하여 강도계수 변화의 원인적 요인을 분석하였다. 또한, 미세 거칠기 변화양상이 전단강도에 미치는 영향을 절리면 강도를 고려하여 분석하였다.

• 한국환경복원기술학회지
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• 제5권4호
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• pp.19-30
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• 2002

The stability of slope using root-pile like to the reinforcements is affected by the interaction behavior mechanism of soil-reinforcements. Through the studying on the interaction in joint of its, therefore, the control roles can be find out in installed slope. In study, the stress level ratio based on the insert angle of installed reinforcements in soil used to numerical analysis, which was results from the duty direct shear test in Lab. The maximum shear strain variation on the reinforcements was observed at insert angle, which was approximately similar to the calculated angle based on the equation proposed by the Jewell. The elasto-plastic joint model on the contact area of soil-reinforcements was presumed, the reinforced soil assumed non-linear elastic model and the reinforcements supposed elastic model, respectively. The finite element analysis of assumed models was performed. The shear strain variation of non-reinforced state obtained by the FEM analysis including elasto-plastic joint elements were shown the rationality of general limit equilibrium analysis for the slope failure mode on driving zone and resistance zone, which based on the stress level step according to failure ratio. Through the variation of shear strain for the variation of inserting angle of reinforcements, the different mechanism on the bending and the shear resistance of reinforcements was shown fair possibility.

• Structural Engineering and Mechanics
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• 제10권6호
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• pp.589-601
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• 2000

A simplified analysis procedure utilizing the strut-tie modeling technique is developed to take a close look into the post-elastic deformation capacity of beam-column connections in ductile reinforced concrete frame structures. Particular emphasis is given to the effect of concrete strength decay and quantity and arrangement of joint shear steel. For this a fan-shaped crack pattern is postulated through the joints. A series of hypothetical rigid nodes are assumed through which struts, ties and boundaries are connected to each other. The equilibrium consideration enables all forces in struts, ties and boundaries to be related through the nodes. The boundary condition surrounding the joints is obtained by the mechanism analysis of the frame structures. In order to avoid a complexity from the indeterminacy of the truss model, it is assumed that all shear steel yielded. It is noted from the previous research that the capacity of struts is limited by the principal tensile strain of the joint panel for which the strain of the transverse diagonal is taken. The post-yield deformation of joint steel is taken to be the only source of the joint shear deformation beyond the elastic range. Both deformations are related by the energy consideration. The analysis is then performed by iteration for a given shear strain. The analysis results indicate that concentrating most of the joint steel near the center of the joint along with higher strength concrete may enhance the post-elastic joint performance.