• 한국강구조학회 논문집
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• 제19권3호
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• pp.303-312
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• 2007

경간 40m~100m 정도 경간에 대해 일반적으로 강 박스 거더교에 대한 설계가 이루어지고 있다. 상부구조의 자중을 줄이기 위해서 복합트러스 교량에서 복부의 콘크리트 웹 대신에 강 사재가 사용되고 있다. 이러한 복합트러스 교량의 설계 시 가장 중요한 부분 중의 하나가 콘크리트 상 하부를 연결하는 연결부의 형태이다. 이러한 접합부는 외부에서 작용하는 조합하중을 분담해야하는데, 아직 이러한 접합구조에 대한 명확한 설계기준이 없는 실정이다. 한계상태에서 격점부의 하중전달에 대한 명확한 연구와 설계방법에 대한 조사가 필요하다. 콘크리트 상 하부를 연결하는 격점부 사재는 다양한 연결형태가 있다. 이번 논문에서는 거셋 플레이트에 용접되어진 그룹 스터드 연결재에 관한 연구가 수행되었다. 25mm 절곡 스터드를 사용하여 수행된 전단실험을 통하여 현재의 스터드 간 최소기준 간격을 만족하는 상태에서는 현재의 설계 규정을 사용할 수 있음을 밝혔다. 휨-전단 실험을 통해서는 조합하중이 작용하는 격점부의 상세를 개선하였다. 격점부의 인발강도를 증진시키기 위해서 절곡 스터드가 제안되었고 그룹 스터드의 최 외측 스터드에 적용되었다. 이러한 결과들을 바탕으로 복합 트러스 교량의 개선된 격점부 상세가 개선되고 설계 방안이 제안되었다.

• Steel and Composite Structures
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• 제36권4호
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• pp.369-381
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• 2020

Nowadays, in prefabricated composite construction, composite action between steel beam and concrete slab is often achieved with positioning of shear connectors in envisaged openings of concrete slabs. Prefabricated concrete slabs are used for composite steel-concrete buildings and bridges, both for the construction of new structures and for renovation of existing ones, significantly reducing construction time. Development of different types of shear connectors represent alternative solution to the traditionally used headed studs, considering their shear resistance, stiffness and ductility. New types of shear connectors tend to reduce the construction time and overall construction cost. Mechanically fastened shear connectors represent a viable alternative to headed studs, considering their fast installation process and shear resistance. X-HVB shear connectors are attached to the steel beam with two cartridge fired pins. The first step towards extensive implementation of X-HVB shear connectors in composite construction is to understand their behaviour through experimental investigation. Results of the push-out tests, in accordance to Eurocode 4, with X-HVB 110 shear connectors positioned in envisaged openings of prefabricated concrete slabs are presented in this paper. The experimental investigation comprised three different specimen's layout. Group arrangement of X-HVB shear connectors in envisaged openings included specimens with minimal recommended distances and specimens with reduced distances between connectors in both directions. Influence of different installation procedures on overall behaviour of the connection is presented, as well as the orientation of shear connectors relative to the shear force direction. Influence of variations is characterized in terms of failure mechanisms, shear resistance and ductility.

• Steel and Composite Structures
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• 제36권1호
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• pp.103-118
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• 2020

The static behavior of grouped large-headed studs (d = 30 mm) embedded in ultra-high performance concrete (UHPC) was investigated by conducting push-out tests and numerical analysis. In the push-out test, no splitting cracks were found in the UHPC slab, and the shank failure control the shear capacity, indicating the large-headed stud matches well with the mechanical properties of UHPC. Besides, it is found that the shear resistance of the stud embedded in UHPC is 11.4% higher than that embedded in normal strength concrete, indicating that the shear resistance was improved. Regarding the numerical analysis, the parametric study was conducted to investigate the influence of the concrete strength, aspect ratio of stud, stud diameter, and the spacing of stud in the direction of shear force on the shear performance of the large-headed stud. It is found that the stud diameter and stud spacing have an obvious influence on the shear resistance. Based on the test and numerical analysis results, a formula was established to predict the load-slip relationship. The comparison indicates that the predicted results agree well with the test results. To accurately predict the shear resistance of the stud embedded in UHPC, a design equation for shear strength is proposed. The ratio of the calculation results to the test results is 0.99.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.595-608
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• 2021

To investigate the mechanical behavior of large stud shear connector embedded in hybrid fiber-reinforced concrete (HFRC), a refined 3D nonlinear finite element (FE) model incorporating the constitutive model of HFRC was developed using ANSYS. Firstly, the test results conducted by the authors (He et al. 2017) were used to validate FE model of push out tests. Secondly, a total of 27 specimens were analyzed with various parameters including fiber volume fractions of HFRC, diameter of studs and HFRC strength. Finally, an empirical equation considering the contribution of steel fiber (SF) and polypropylene fiber (PF) was recommended to estimate the ultimate capacity of large stud shear connector embedded in HFRC.

• Steel and Composite Structures
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• 제26권2호
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• pp.183-196
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• 2018

The traditional prestressed concrete composite box-girders with corrugated steel webs have several drawbacks such as large deflection and potential local buckling. In this study, two methods were investigated to optimize and improve the prestressed concrete composite box-girders with corrugated steel webs. The first method was to replace the concrete bottom slab with a steel plate and the second method was to support the concrete bottom slab on the steel flanges. The behavior of the prestressed concrete composite box-girders with corrugated steel webs with either method was studied by experiments on three specimens. The test results showed that behavior of the optimized and upgraded prestressed concrete composite box-girders with corrugated steel webs, including ultimate bearing capacity, flexural stiffness, and crack resistance, is greatly improved. In addition, the influence of different shear connectors, including perfobond leisten (PBL) and stud shear connectors, on the behavior of prestressed concrete composite box-girders with corrugated steel webs was studied. The results showed that PBL shear connectors can greatly improve the ultimate bearing capacity, flexural stiffness and crack resistance property of the prestressed concrete composite box-girders with corrugated steel webs. However, for the efficiency of prestressing introduced into the girder, the PBL shear connectors do not perform as well as the stud shear connectors.

• 한국강구조학회 논문집
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• 제28권6호
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• pp.415-425
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• 2016

스틸스터드 내력벽 시스템은 국외에서 중고층형 모듈러 건축에 널리 사용되는 구조형식이다. 국내의 중고층형 모듈러 시스템에 스틸 스터드 벽체를 적용하기 위해서는 내진성능 확보가 필수적이다. 본 연구에서는 스트랩브레이스를 갖는 모듈러 건축 스틸스터드 내력벽 시스템의 횡력저항성능 및 유효강성을 제안하였다. 스트랩 브레이스와 수직외측스터드의 사양을 달리하는 2개의 실물 실험체에 대해 주기하중에 대한 실험을 실시하여 제안된 설계식을 검증하였다. 수직외측스터드의 휨거동을 고려할 수 있는 설계식을 통해 실험체의 공칭강도, 탄성강성, 항복변위 등을 예측하고 실험을 통해 검증하였다. 실험에 의한 최대강도는 예측식 대비 1.11~1.18배 수준으로 평가되었다. 박판의 스트랩 브레이스를 갖는 스트랩 스터드패널은 일반적으로 에너지소산능력이 매우 낮은 것으로 평가되나, 본 연구에서 제안한 수직외측스터드의 유효높이를 줄이고 브레이스의 각도를 낮춘 시스템의 경우 등가점성감쇠비가 최대 9.42% 수준으로 충분한 에너지소산능력이 확보될 수 있음을 확인하였다.

• Steel and Composite Structures
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• 제36권5호
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• pp.507-519
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• 2020

Double skin composite walls are increasingly popular and have been applied to many safety-related facilities. They come from the concept of composite slabs. Conventional connectors such as shear studs and binding bars were used in previous studies to act as the internal mechanical connectors to lock the external steel faceplates to the concrete core. However, the restraint effects of these connectors were sometimes not strong enough. In this research, a recently proposed unique type of steel truss was employed along the wall height to enhance the composite action between the two materials. Concrete-filled tube columns were used as the boundary elements. Due to the existence of boundary columns, the restraints of steel faceplates to the concrete differ significantly for the walls with different widths. Therefore, there is a need to explore the effect of height-to-width ratio on the structural behavior of the wall. In the test program, three specimens were designed with the height of 3000 mm, the thickness of 150 mm, and different widths, to simulate the real walls in practice. Axial compression was applied by two actuators on the tested walls. The axial behavior of the walls was evaluated based on the analysis of test results. The influences of height-to-width ratio on structural performance were evaluated. Finally, discussion was made on code-based design.

• 대한의생명과학회지
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• 제7권4호
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• pp.211-216
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• 2001

This studs was carried out to evaluate KBrO$_3$-induced acute toxicity by clinical pathological parameters in rats. Fourty rats were divided into 4 groups including normal group and three KBrO$_3$-treated groups with doses of 200, 300, and 400 mg/kg, p. o., respectively. Creatinine and BUN were increased remarkably by KBrO$_3$ at 400 mg/kg, respectively (p<0.05, p<0.01). Phosphorus content increased two times the control at 400 mg/kg (p<0.05). Osmolarity was increased, whereas $CO_2$ content showed decrease at 400 mg/kg, respectively (p<0.01, p<0.05). Histopathological findings also showed dose-dependent renal failure. On the other hand, AST was increased three times the control at 400 mg/kg (p<0.01). WBC was increased by KBrO$_3$ depending on the dosage. Platelet was decreased at 200 mg/kg, whereas it was increased at 400 mg/kg (p<0.05). The results above suggest that clinical pathological parameters could be used as indices for the evaluation of KBrO$_3$-induced acute toxic reponse occuring in not only kidney but other organs including liver, when the dosage is as high as 400 mg/kg.

• Steel and Composite Structures
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• 제49권2호
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• pp.215-230
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• 2023

Cable-girder anchorage joint is the critical part of cable-supported bridges. Tensile-plate anchorage (TPA) is one of the most commonly used types of cable-girder anchorage joints in steel girder cable-supported bridges. In recent years, it has been proposed by bridge designers to apply TPA to concrete girder cable-supported bridges to form composite cable-girder anchorage joint (CCGAJ). In this paper, the mechanical performance of CCGAJ under tensile force is studied through experimental and numerical analyses. Firstly, the effects of the external prestressing (EP) and the bearing plate (BP) on the mechanical performance of CCGAJ were investigated through three tests. Then, finite element model was established for parametrical study, and was verified by the experimental results. Then, the effects of shear connector forms, EP, BP, vertical rebar rate, and perforated rebar rate on the tensile capacity of CCGAJ were investigated through numerical analyses. The results show that the tensile capacity of CCGAJ depends on the first row of PR. The failure mode of CCGAJ using headed stud connectors is to form a shear failure surface at the end of the studs while the failure mode using PBLs is similar to the bending of a deep girder. Finally, based on the strut-and-tie model (STM), a calculation method for CCGAJ tensile capacity was proposed, which has a high accuracy and can be used to calculate the tensile capacity of CCGAJ.

• 한국가금학회지
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• 제29권1호
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• pp.25-35
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• 2002

조기제한사양의 강도(정도)와 시기 및 기간이 육계의 보상성장과 사료효율 및 복강지방 축적에 미치는 영향을 구명하기 위해 2개의 실험을 실시하였는데, 실험 1에서는 7일령된 무감별 육계 240수를 4처리 3반복에 반복당 20수씩 공시하여 7일령에서부터 49일령까지 실시하였다. 대조구(C)는 7일령부터 49일령까지 전기간 육계 전기사료와 후기사료를 자유채식을 시켰으며, 시험구(T1,T2 및 T3)들은 각각 1일 0.75 kcal ME/9B $W^{0.67}$로 7일령부터 9일령까지 3일간, 1.50 kcal ME/gB $W^{0.67}$로 7일령부터 11일령까지 5일간 및 2.25 kcal ME/gB\$^{0.67}$로 7일령부터 13일령까지 7일간 육계전기사료를 제한급여하였다. 실험 2는 4일령된 무감별 육계 420수를 7처리 3반복, 반복당 20수씩 공시하여 4일령에서부터 49일령까지 실시하였는데 대조구(C)는 4일령부터 49일령까지 전기간 육계 전기사료와 후기사료를 자유채식을 시켰으며, 시험구(T1~T6)들은 모두 1일 0.75kcal ME/gB $W^{0.67}$로 4,7일 및 10일령에 3일간 또는 5일간육계전기사료를 제한급여하였으며, 제한사양이 끝난 시험구들은 전기사료 및 후기사료를 자유채식시켰다. 실험 1에서 제한사양기간을 포함한 21일령가지의 증체량은 대조구에 비해 시험구들이 유의적으로 적었으나(P<0.05), 22일령부터 49일령까지의 증체량은 대조구에 비해 시험구들이 유의적으로 높았으며(P<0.05), 전기간인 7일령부터 49일령까지의 증체량과 49일령 체중은 처리간에 유의적 차이가 없었다. 제한사양후부터 21일령까지의 사료섭취량은 T1구를 제외한 나머지 시험구에서는 대조구와 유의적인 차이를 보이지 않았으며, 22~47일령의 사료섭취량은 처리간에 유의적인 차이가 없었으나, 전기간 섭취량은 대조구에 비해 시험구들이 유의적으로 적게 섭취하였다 (P<0.05). 제한사양기간을 포함한 7일령부터 21일령까지의 사료요구율은 T1구만 유의적으로 낮았으며(P<0.05), 22일령부터 49일령가지의 사료요구율과 전기간동안의 사료요구율은 대조구에 비해서 시험구들이 유의적으로 낮았다(P<0.05) , 복강내지방함량 및 전기간 폐사율은 처리간에 유의적 차이가 없었다.