• 한국강구조학회 논문집
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• 제13권6호
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• pp.641-649
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• 2001

본 논문에서는 데크플레이트의 웨브 국부좌굴에 관한 실용적인 내력식을 제안하고자 한다. 실험에서 유추된 해석모델을 이론적으로 규명한 기존의 연구를 바탕으로 내력에 영향을 미치는 주요 변수들을 조사 분석하여 관련 함수들을 유도한다. 각 변수들을 기존의 실험자료와 종합적으로 비교 분석하여 간편한 내력식을 제안한다. 유럽기준 EC 3 부록 Z 에 따른 통계평가로부터 저항 부분안전계수 ${\gamma}_M$ 을 구하며 목표로 하는 값 1.1과 비교되어진다.

• 한국강구조학회 논문집
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• 제17권6호통권79호
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• pp.737-747
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• 2005

강재 보와 콘크리트 슬래브로 구성되어 지는 합성보에서 두 부재는 일반적으로 전단연결재에 의해 서로 합성되어져 일체적인 구조거동을 하게 된다. 현재까지 전단연결재로서는 스터드(stud)가 널리 사용되어지고 있다. 합성보의 구조적 거동은 사용된 부재의 재료적 특성 외에도 스터드에 의한 전단합성작용에 의해 많은 영향을 받게 된다. 합성보 전단연결부에서의 전단합성거동은 합성보에서가 아닌 단순화된 Push-Out 시험체(Push-Out Test Specimen)에 의해 실험적으로 결정되고 있다. 최근의 연구결과에 따르면, Push-Out 실험에서 얻은 전단 스터드의 합성거동과 실제 합성보에서의 전단합성거동에는 분명한 차이점이 존재하며, 특히 부분합성된 합성보에서는 그 차이가 매우 크다는 것이 밝혀지고 있다. 본 연구에서는 표준 Push-Out 시험체 및 합성보의 구조거동 해석을 위해, Push-Out 실험으로부터 결정되는 스터드에 대한 하중-상대변위 곡선의 도입이 필요 없는 3차원 유한요소모델을 개발하였다. 해석결과의 비교 분석으로부터 합성보 전단연결부에서의 합성거동을 평가할 수 있었고, 이를 Push-Out 실험결과와 비교하여 보았으며 전단합성거동의 차이점에 대한 구체적 원인을 찾을 수 있었다.

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2402-2408
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• 2009

고장력볼트를 이용한 강부재의 체결에서 모재 및 덮개판의 과대공으로 인한 단면결손이 체결부에서 내하력의 저하가 우려되어 정적 인장시험을 실시하였다. 인장시험을 통하여 구해진 체결부의 파단시 최대하중을 단면결손율 및 설계강도와 비교하여 체결부의 내하력 변화를 파악하였다. 이에 따르면 단면결손율이 클수록 강도저하율이 컸으며 특히, 모재의 단면결손이 덮개판의 단면결손보다 강도저하에 대한 영향이 훨씬 큰 것으로 나타났다. 모재 및 덮개판을 과대공으로 제작한 고장력볼트 체결부는 표준공의 경우보다 내하성능이 다소 저하되었지만 파단시의 최대인장강도는 설계파단강도보다 15%이상 크게 나타났다. 본 연구에서는 과대공으로 제작된 고장력볼트 체결부에서 내하력저하에 미치는 영향이 미미하므로 강부재의 체결시공에 있어 과대공의 허용은 경제성과 효율성의 고취에 기여할 수 있을 것으로 판단되었다.

• Steel and Composite Structures
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• 제18권4호
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• pp.1045-1062
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• 2015

Concrete-filled circular t steel tubular joints (CFSTJs) in practice are frequently subjected to fluctuated loadings caused by wind, earthquake and so on. As fatigue crack is sensitive to such cyclic loadings, assessment on performance of CFSTJs with crack-like defect attracts more concerns because both high stress concentration at the brace/chord intersection and welding residual stresses along weld toe cause the materials in the region around the intersection to be more brittle. Once crack initiates and propagates along the weld toe, tri-axial stresses in high gradient around the crack front exist, which may bring brittle fracture failure. Additionally, the stiffness and the load carrying capacity of the CFSTJs with crack may decrease due to the weakened connection at the intersection. To study the behaviour of CFSTJs with initial crack, experimental tests have been carried out on three full-scale CFCST T-joints with same configuration. The three specimens include one uncracked joint and two corresponding cracked joints. Load-displacement and load-deformation curves, failure mode and crack propagation are obtained from the experiment measurement. According to the experimental results, it can be found that he load carrying capacity of the cracked joints is decreased by more than 10% compared with the uncracked joint. The effect of crack depth on the load carrying capacity of CFCST T-joints seems to be slight. The failure mode of the cracked CFCST T-joints represents as plastic yielding rather than brittle fracture through experimental observation.

• Steel and Composite Structures
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• 제16권5호
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• pp.455-480
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• 2014

Sixteen concrete filled square CFRP-steel tubular (S-CFRP-CFST) stub columns under axial compression were experimentally investigated. The experimental results showed that the failure mode of the specimens is strength loss of the materials, and the confined concrete has good plasticity due to confinement of the CFRP-steel composite tube. The steel tube and CFRP can work concurrently. The load versus longitudinal strain curves of the specimens can be divided into 3 stages, i.e., elastic stage, elasto-plastic stage and softening stage. Analysis based on finite element method showed that the longitudinal stress of the steel tube keeps almost constant along axial direction, and the transverse stress at the corner of the concrete is the maximum. The confinement effect of the outer tube to the concrete is mainly focused on the corner. The confinements along the side of the cross-section and the height of the specimen are both non-uniform. The adhesive strength has little effect both on the load versus longitudinal strain curves and on the confinement force versus longitudinal strain curves. With the increasing of the initial stress in the steel tube, the load carrying capacity, the stiffness and the peak value of the average confinement force are all reduced. Equation for calculating the load carrying capacity of the composite stub columns is presented, and the estimated results agree well with the experimental results.

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.81-92
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• 2022

Ultra-high performance fiber reinforced concrete (UHPFRC) is a composite building material with high ductility, fatigue resistance, fracture toughness, durability, and energy absorption capacity. The aim of this study is to develop a nonlinear finite element model that can simulate the response of the UHPFRC beam exposed to impact loads. A nonlinear finite element model was developed in ABAQUS to simulate the real response of UHPFRC beams. The numerical results showed that the model was highly successful to capture the experimental results of selected beams from the literature. A parametric study was carried out to investigate the effects of reinforcement ratio and impact velocity on the response of the UHPFRC beam in terms of midpoint displacement, impact load value, and residual load-carrying capacity. In the parametric study, the nonlinear analysis was performed in two steps for 12 different finite element models. In the first step, dynamic analysis was performed to monitor the response of the UHPFRC beam under impact loads. In the second step, static analysis was conducted to determine the residual load-carrying capacity of the beams. The parametric study has shown that the reinforcement ratio and the impact velocity affect maximum and residual displacement value substantially.

• 한국강구조학회 논문집
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• 제17권1호통권74호
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• pp.83-92
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• 2005

본 논문은 압축과 모멘트 조합하중을 받는 냉간성형강 기둥의 내력성능을 평가하는데 목적이 있다. 단면은 춤이 90, 150 mm이고 웨브에 엠보싱이 있는 립 ㄷ형강이다. 부재길이와 단부모멘트비를 변수로 하였고, 편심압축력을 가력하여 총 24개 실물실험을 수행하였다. 미국 AISI와 유럽 EC3 기준의 특징을 체계적으로 분석하였고, 실험결과와 기준 산정결과를 비교하였다. 두 기준 모두 합리적임을 알 수 있었다.

• 한국안전학회지
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• 제25권6호
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• pp.70-74
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• 2010

For each strand of wirerope sling, the international standards, ISO-8794, EN-13414 specify that the splice shall have five series of load carrying tucks. At least three of the load carrying tucks shall be made with the whole strand. And, the breaking force of the splice shall not be less than 70% or 80% of that of rope. But, There are no prescriptions for splicing types against different efficiency of each splicing type being used many workplace. In this study, analysis the work limit load efficiency according to variation of number of tucks and splicing types by experimental method As a result, the number of tucks 3+2 had the highest breaking efficiency.

• 한국농공학회지
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• 제45권2호
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• pp.78-85
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• 2003

This study aims to investigate the effect of partially distributed loads on the static behavior of parabolic arches by using the elastic-plastic finite element model. For this purpose, the vertical, the radial, and the anti-symmetric load cases are considered, and the ratio of loading range and arch span is increased from 20% to 100%. Also, the elastic-visco-plastic analysis has been carried out to estimate the elapse time to reach the stable state of arches when the ultimate load obtained by the finite element analysis is applied. It is noted that the ultimate load carrying capacities of parabolic arches are 6.929 tf/$m^2$ for the radial load case, and 8.057 tf/$m^2$ for the vertical load case. On the other hand, the ultimate load is drastically reduced as 2.659 tf/$m^2$ for the anti-symmetric load case. It is also shown that the maximum ultimate load occurs at the full ranging distributed load, however, the minimum ultimate loads of the radial and vortical load cases are obtained by 2.336 tf/$m^2$, 2.256 tf/$m^2$, respectively, when the partially distributed load is applied at the 40% range of full arch span.

• 대한의용생체공학회:의공학회지
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• 제32권3호
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• pp.230-236
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• 2011

The aim of this study was to investigate the alteration of lumbar spine and trunk postures on different load-carrying types and amounts under static loading. Two load-carrying types(unilateral carrying: UC vs. bilateral carrying: BC) and four different loads(0, 5, 10, and 15 kg) were randomly tested in this study. Carrying a heavy bag would affect human body posture, specifically lumbar spine curvature, which is considered as one of sources of back problems. Previous studies have not paid attention to the approach of the multisegment model of the lumbar spine and trunk. This study separated two compartments of trunk segment(the lumbar and thorax) in the analysis. The multisegment model of the lumbar spine in addition to Helen-Hayes marker set was used. Eight motion analysis cameras and a force plate were utilized. Ten male subjects(mean mass, $70.6{\pm}3.97$ kg; mean height, $178{\pm}4.18$ m) having no musculoskeletal disease participated in this study. We analyzed trunk angles in three anatomical planes and the spinal curvature in sagittal and frontal planes. Increased loading in both UC and BC significantly resulted in increases in trunk forward lean but only UC induced increases in trunk lateral lean. In addition, increased loading in BC produced flatten lumbar curvature in sagittal plane. As far as coupling motion, subjects tended to use axial rotation of the lumbar spine in transverse plane in response to increased UC loading. Finally, it is concluded that the increased static loading in UC rather than in BC tends to causes combined alterations of the spinal postures(sagittal and transverse planes together), which would be vulnerable to improper mechanical stresses on the spine.