• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.481-486
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• 1998

In this paper, elastic and inelastic behavior of exterior joint of moment-resisting R.C frame with non-seismic detail subjected to reversed cyclic lateral load such as earthquake excitations was investigated. 1/2-scals subassemblage exterior beam-column joint including slab was manufactured based on similitude law. Then, pseudo static test under the displacement control was performed. The results of 1)crack pattern and failure mode, 2)degradation stiffness and strength, energy dissipation capacity from load-displacement hysteresis curve, 3)strain of steel were analysed.

• Geomechanics and Engineering
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• 제28권2호
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• pp.117-133
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• 2022

Determination of the mechanical behaviour of jointed rock masses has been a challenge for rock engineers for decades. This problem is more pronounced for non-persistent jointed rock masses due to complicated interaction of rock bridges on the overall behaviour. This paper aims to study the effect of a non-persistent joint set configuration on the mechanical behaviour of rock materials under both uniaxial and biaxial compression tests using a discrete element code. The numerical simulation of biaxial compressive strength of rock masses has been challenging in the past due to shortcomings of bonded particle models in reproducing the failure envelope of rock materials. This problem was resolved in this study by employing the flat-joint contact model. The validity of the numerical model was investigated through a comprehensive comparative study against physical uniaxial and biaxial compression experiments. Good agreement was found between numerical and experimental tests in terms of the recorded peak strength and the failure mode in both loading conditions. Studies on the effect of joint orientation on the failure mode showed that four zones of intact, transition to block rotation, block rotation and transition to intact failure occurs when the joint dip angle varies from 0° to 90°. It was found that the applied confining stress can significantly alter the range of these zones. It was observed that the minimum strength occurs at the joint dip angle of around 45 degrees under different confining stresses. It was also found that the joint orientation can alter the post peak behaviour and the lowest brittleness was observed at the block rotation zone.

• Journal of Welding and Joining
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• 제33권6호
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• pp.49-54
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• 2015

Welding process is of importance to assemble products or structures, but also the process is structural weakness due to stress concentration in welding joint. The fatigue design of welded joint requires time & labor consuming fatigue test because the fatigue life is various according to the depth of joint, joint type and load type etc. In fatigue design codes, they guide to classify welding joints with their shape( BS7608, IIW Documents) and provide fatigue assessment information. In terms of numerical method for fatigue analysis, it is also difficult to decide the stress peak in joint because of mesh sensitivity which means that stress value is varies with element type or size on stress concentration zone. Hot-spot method is used generally, but Battelle of United States proposed Master S-N Curve based on structural stresses converted by mechanical equilibrium theory. In this research, we extracted master S-N curve from Battelle's fatigue test DB including test data of various welding joints to apply on Non-Load-Carrying cruciform Joint. Comparing fatigue results between the case of using normal stress and case of structural stress cor the cruciform Joint, The suggested Battelle method showed successive results.

• 정형스포츠물리치료학회지
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• 제14권2호
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• pp.1-8
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• 2018

Purpose: This study investigated the effect of the augmented reality (AR)-based knee joint short period exercise program and used a motion analyzer with a 3D camera to determine the range of motion and dynamic balance and further investigate the effects of therapeutic exercise on patients. Methods: This study used AR-based motion analysis and a Y-balance test to measure the range of motion (ROM) of each joint: the hip joint and the knee joint. After the measurements, an exercise program was applied to the subjects, using the knee motion program function, and the muscles of the quadriceps femoris and the hamstring were stretched or strengthened. Results: Our results showed knee joint extension at the dominant hip joint flexion position. While there was no significant difference (p>.05) at this position, there were significant differences in the non-dominant hips, unbalanced knee joint flexion, and superior knee joint flexion (p<.05). The Y-balance test using the non-dominant leg supported by the dominant legs showed that the absolute reach was $69.70{\pm}7.06cm$ before the exercise, and the absolute reach after the exercise was $77.56{\pm}6.09cm$ (p<.05). Conclusions: There was a significant difference when the movement of the lower limbs supported the superior limbs, and a significant difference was found in the ROM when the non-dominant side supported the dominant side. Therefore, the AR-based exercise program improves the balance of the human body and the range of motion of the joints, and research that aims to improve patients abilities should continue.

• Structural Engineering and Mechanics
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• 제21권6호
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• pp.677-698
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• 2005

In engineering practice, tubular connections are usually assumed pinned or rigid. Recent research showed that tubular joints may exhibit non-rigid behavior under axial or bending loads. This paper is concerned with establishing a new classification for tubular joints and investigating the effect of joint rigidity on the global behavior of CHS (Circular Hollow Section) lattice girders. Parametric formulae for predicting tubular joint rigidities are proposed, which are based on the finite element analyses through systematic variation of the main geometric parameters. Comparison with test results proves the reliability of these formulae. By considering the deformation patterns of respective parts of Vierendeel lattice girders, the boundary between rigid and semirigid tubular connections is built in terms of joint bending rigidity. In order to include characteristics of joint rigidity in the global structural analysis, a type of semirigid element which can effectively reflect the interaction of two braces in K joints is introduced and validated. The numerical example of a Warren lattice girder with different joint models shows the great effect of tubular joint rigidities on the internal forces, deformation and secondary stresses.

• 한국지진공학회논문집
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• 제21권3호
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• pp.115-123
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• 2017

To investigate the cyclic characteristics of the retrofitted exterior joints of RC frame with haunch, 70% scaled 6 beam-column exterior joint subassemblies were designed according to design guideline according to 1988 and tested with cyclic loading up to 3.5% story drift ratio. During the experiments axial forces are applied to columns to simulate gravity load. Experimental results shows that the strength of retrofitted specimens was increased steadily until 2.5% story drift ratio and their strengths increased more than 1.7 times of the non-retrofitted in case that main bar was bent away from exterior joint. The joint strength and effective stiffness of the retrofitted specimen was increased and results in more deformation capacity compared to the non-retrofitted.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.793-796
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• 2008

교량 신축이음장치의 파손 유형은 주로 후타재(무수축 모르타르)와 관련된 부분에서 많이 발생된다. 또 다른 문제는 중차량 통과에 따른 충격과 진동하중으로 인해서 신축이음장치를 후타재에 고정하기 위해서 사용하는 앵커 풀림 현상이다. 본 연구에서는 무수축 모르타르의 파괴에 따른 신축이음 장치의 파손을 방지하기 위해 탄성콘크리트를 개발하였다. 개발된 탄성콘크리트와 현재 주로 사용하고 있는 무수축 모르타르의 인발성능을 비교하였다. 또한, 후타재와 신축이음장치를 일체화하여 후타재의 파손을 방지하고 신축이음장치를 쉽게 교체할 수 있는 앵커 시스템을 개발하였다.

• 한국지반공학회논문집
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• 제15권5호
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• pp.217-228
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• 1999

본 논문에서는 절리암반에서 발생하는 지하수 유동과 굴착된 지하공동으로의 지하수 유입량을 해석하는 대표체적법, 비대표체적법 및 절리망 해석법을 소개하고 절리의 수와 공동의 직경을 변화시키면서 각 해석법의 특징과 결과를 비교하였다. 선처리 과정으로서 다수의 절리가 서로 교차하는 절리암반의 등가 수리전도계수를 산정하는 이론과 계산 과정(일명, 순차적 해석)이 소개되었다. 유한요소망과 절리도 및 순차적 해석을 이용하여 445개 요소 각각의 등가 수리전도계수를 계산하였으며 절리암반의 비균질 수리전도성과 대표물성 결정에 관해 논의하였다. 대표체적법에서는 대표물성을 통해 절리암반의 균질화가 이루어졌으며 따라서 절리밀도, 공동의 직경 및 수리전도대비의 증가에 따른 지하수 유입량의 증가도 규칙적이며 일관성 있는 경향을 보였다. 비대표체적법에서는 암반의 비균질성이 요소 단위로 해석에 반영됨으로써 유입량의 변화 양상은 불규칙하였으나 특성 치수가 증가함에 따라 대표체적법의 결과에 접근하는 경향을 보였다. 절리망 해석은 절리밀도, 공동크기 및 절리망과 공동의 교차 여부 등에 가장 민감하게 반응하였으나 해석결과의 신뢰도가 개별 절리에 관한 자료에 너무 의존하게 되는 단점이 있다. 제한된 범위에서 수집될 수밖에 없는 현장 절리자료의 불확실성을 감안할 때 대표체적법과 비대표체적법이 실질적으로 더 합리적인 해석방법으로 인식되었다.

• 지질공학
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• 제34권2호
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• pp.317-327
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• 2024

대규모 암반 사면에서 비연속성의 절리계가 발달할 때, 계단상 활동면에 의한 사면 파괴가 발생할 수 있다. 계단상 활동면은 절리-절리 활동면 또는 절리-암교 활동면으로 구분할 수 있으며, 절리-암교 활동면에서 암교는 절리와 평행한 전단 저항과 절리에 수직인 인장 저항을 제공한다. 계단 경로 파괴는 활동 암괴의 하중에 의해 암교의 파괴가 발생하여 암교 양단의 두 절리가 연결되며 발생한다. 암교의 길이가 동일하다면 암석의 인장강도가 전단강도에 비해 낮으므로 절리에 수직으로 형성된 암교가 파괴에 취약하며, 불연속면 간격/길이의 비가 작을수록 계단 경로 파괴의 가능성이 커진다. 비연속성의 절리가 발달하는 암반 사면의 계단상 활동 파괴 위험에 대한 평가를 위해서는 체계적인 불연속면 조사 및 분석을 통해 계단 경로 파괴면을 구성하여 한계 평형 해석 또는 수치 해석 등의 안정성 평가를 수행하여야 한다.

• Earthquakes and Structures
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• 제21권6호
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• pp.613-625
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• 2021

Non-seismically designed eccentric reinforced concrete beam-column joints were extensively used in existing reinforced concrete frame buildings, which were found to be vulnerable to seismic action in many incidences. To provide a fundamental understanding of the seismic performance and failure mechanism of the joints, three 2/3-scale exterior beam-column joints with non-seismically designed details were cast and tested under reversed cyclic loads simulating earthquake excitation. In this investigation, particular emphasis was given on the effects of the eccentricity between the centerlines of the beam and the column. It is shown that the eccentricity had significant effects on the damage characteristics, shear strength, and displacement ductility of the specimens. In addition, shear deformation and the strain of joint hoops were found to concentrate on the eccentric face of the joint. The results demonstrated that the specimen with an eccentricity of 1/4 column width failed in a brittle manner with premature joint shear failure, while the other specimens with less or no eccentricity failed in a ductile manner with joint shear failure after beam flexural yielding. Test results are compared with those predicted by three seismic design codes and two non-seismic design codes. In general, the codes do not accurately predict the shear strength of the eccentric joints with non-seismic details.