• 융합정보논문지
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• 제7권2호
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• pp.91-99
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• 2017

본 연구는 기본동작인 분리(isolation) 동작을 통해 K-pop과 B-boy의 동작의 특성을 생체역학적 변인(CoM, CoM velocity, planar angle, joint moment )중심으로 그 차이점을 규명하는데 목적이 있으며, spss 18.0을 이용하여 독립변인 t검증을 실시하였다. 그 결과 첫째, 국면1과 국면2에서 K-pop 댄서의 CoM 합성변위는 B-boy 보다 더 크게 나타났다(p<.05). 둘째, 국면2와 국면3에서 CoM의 이동속도는 K-pop댄서가 B-boy 보다 더 빠른 것으로 나타났다(p<.05). 셋째, 국면1에서 몸통과 골반의 수평각은 K-pop댄서의 오른쪽 수평각, 국면2와 국면3에서 B-boy의 왼쪽 수평각이 더 큰 것으로 나타났다(p<.05). 넷째, 합성모멘트는 엉덩관절의 국면1에서 B-boy가 더 크게 나타났고, 무릎 관절은 국면2, 국면3, 국면4에서 발목관절은 국면3에서 K-pop 댄서가 더 큰 회전력이 나타났다(p<.05). 따라서 동일한 분리 동작이라 할지라도, K-pop과 B-boy 댄서는 다르게 수행함을 발견하게 되었다.

• 한국강구조학회 논문집
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• 제23권3호
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• pp.377-384
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• 2011

최근에 국내의 건설현장에서는 공기단축과 시공성 향상을 위하여 구조분야에서 다양한 공법이 개발되고 있으며 HRC 공법도 그중 하나로서 주차장이나 사무소 건물에 적용이 가능하다. 이 공법은 구조적 효율성을 높이기 위하여 보의 중간에 겔버 조인트를 도입하고 있으며, 핀 접합부에는 공장에서 제작되는 HRC 복합보 내부에 스터드 볼트가 용접된 연결플레이트를 삽입하여 현장에서 철골보와 볼트접합이 가능하도록 하였다. 이 연구에서는 철골보와의 핀접합을 위해 HRC 복합보의 내부에 삽입된 연결플레이트와 콘크리트와의 일체성 확보를 검증하기 위하여 6개의 실험체에 대하여 연결플레이트의 길이와 높이, 플레이트에 용접되는 스터드 볼트의 수를 변수로 하여 실험을 실시하였다. 실험결과는 처짐과 철근의 변형도에 대하여 현행규준에 따라 비교하였다. 실험결과 주어진 하중의 범위 내에서 스터드 볼트가 용접된 연결플레이트와 철근콘크리트보는 일체성을 확보하고 있는 것으로 조사되었다.

• 소성∙가공
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• 제24권1호
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• pp.37-43
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• 2015

The purpose of the current study is to improve the clinching joint strength of aluminum and fiber metal laminates (FMLs) comprised of three layers. The joining of FML and Al 5052 by a conventional clinching joint has some disadvantages such as necking of the upper sheet, lack of interlocking, defects caused by the vertical load, and especially loss of strength of the composite material due to the low ductility. In the current study, a tapered-hole clinching method is proposed as an alternative for the joining of Al 5052 and FMLs. A hole with a tapered shape is formed before the joining process. The design parameters were evaluated using the Taguchi method for the geometry of the tapered hole in order to determine the maximum separation load. The diameter of the punch corner, clearance, punch stroke and the tapered length were used as the main variables in the Taguchi method. In conclusion, the contribution ratio for each of the fours variable examined was 35.07%, 22.44%, 21.32% and 14.11%, respectively. In addition, the appropriate combination of the design parameters can make a 5% improvement in the vertical direction joint strength.

• Steel and Composite Structures
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• 제21권5호
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• pp.963-980
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• 2016

The jib system with middle strut is widely used to achieve the large arm length in the large scale tower crane and the deployability in the mobile construction crane. In this paper, an analytical solution for the out-of-plane buckling of the jib system with middle strut is proposed. To obtain the analytical expression of the buckling characteristic equation, the method of differential equation was adopted by establishing the bending and torsional differential equation of the jib system under the instability critical state. Compared with the numerical solutions of the finite element software ANSYS, the analytical results in this work agree well with them. Therefore, the correctness of the results in this work can be confirmed. Then the influences of the lateral stiffness of the cable fixed joint, the dip angle of the strut, the inertia moment of the strut, and the horizontal position of the cable fixed joint on the out-of-plane buckling behavior of the jib system were investigated.

• Steel and Composite Structures
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• 제31권5호
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• pp.453-467
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• 2019

Portal frame structures, made up of cold-formed steel trusses, are increasingly being used for lightweight building construction. A novel pin-jointed moment connector, called the Howick Rivet Connector (HRC), was developed and tested previously in T-joints and truss assemblage to determine its reliable strength, stiffness and moment resisting capacity. This paper presents an experimental study on the HRC, in moment resisting cold-formed steel trusses. The connection method is devised where intersecting truss members are confined by a gusset connected by HRCs to create a rigid moment connection. In total, three large scale experiments were conducted to determine the elastic capacity and cyclic behaviour of the gusseted truss moment connection comprising HRC connectors. Theoretical failure loads were also calculated and compared against the experimental failure loads. Results show that the HRCs work effectively at carrying high shear loads between the members of the truss, enabling rigid behaviour to be developed and giving elastic behaviour without tilting up to a defined yield point. An extended gusset connection has been proposed to maximize the moment carrying capacity in a truss knee connection using the HRCs, in which they are aligned around the perimeter of the gusset to maximize the moment capacity and to increase the stability of the truss knee joint.

• Steel and Composite Structures
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• 제18권3호
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• pp.739-756
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• 2015

This paper presents investigations on the hysteretic behavior of concrete-filled circular tubular (CFCT) T-joints subjected to axial cyclic loading at brace end. In the experimental study, four specimens are fabricated and tested. The chord members of the tested specimens are filled with concrete along their full length and the braces are hollow section. Failure modes and load-displacement hysteretic curves of all the specimens obtained from experimental tests are given and discussed. Some indicators, in terms of stiffness deterioration, strength deterioration, ductility and energy dissipation, are analyzed to assess the seismic performance of CFCT joints. Test results indicate that the failures are primarily caused by crack cutting through the chord wall, convex deformation on the chord surface near brace/chord intersection and crushing of the core concrete. Hysteretic curves of all the specimens are plump, and no obvious pinching phenomenon is found. The energy dissipation result shows that the inelastic deformation is the main energy dissipation mechanism. It is also found from experimental results that the CFCT joints show clear and steady stiffness deterioration with the increase of displacement after yielding. However, all the specimens do not perform significant strength deterioration before failure. The effect of joint geometric parameters ${\beta}$ and ${\gamma}$ of the four specimens on hysteretic performance is also discussed.

• Steel and Composite Structures
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• 제29권5호
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• pp.635-645
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• 2018

Beam-column joints play a significant role in static and dynamic performances of reinforced concrete frame structures. This study contributes a numerical approach of topologically optimal design of carbon fiber reinforced plastics (CFRP) to retrofit existing beam-column connections with crack patterns. In recent, CFRP is used commonly in the rehabilitation and strengthening of concrete members due to the remarkable properties, such as lightweight, anti-corrosion and simplicity to execute construction. With the target to provide an optimal CFRP configuration to effectively retrofit the beam-column connection under semi-failure situation such as given cracks, extended finite element method (X-FEM) is used by combining with multi-material topology optimization (MTO) as a mechanical description approach for strong discontinuity state to mechanically model cracked structures. The well founded mathematical formulation of topology optimization problem for cracked structures by using multiple materials is described in detail in this study. In addition, moved and regularized Heaviside functions (MRHF), that have the role of a filter in multiple materials case, is also considered. The numerical example results illustrated in two cases of beam-column joints with stationary cracks verify the validity, benefit and supremacy of the proposed method.

• Steel and Composite Structures
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• 제15권5호
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• pp.507-518
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• 2013

The seismic performance of six types of weak-axis steel moment connections was investigated through cyclic testing of six full-scale specimens. These weak-axis moment connections were the column-tree type, WUF-B type, FF-W type, WFP type, BFP-B type and DST type weak-axis connections. The testing results showed that each of these weak-axis connection types achieved excellent seismic performance, except the WFP and the WUF-B types. The WFP and WUF-B connections displayed poor seismic performance because a fracture appeared prematurely at the weld joint due to stress concentrations. The column-tree type connection showed the best seismic behavior such that the story drift ratio could reach 5%.

• Steel and Composite Structures
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• 제2권6호
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• pp.411-428
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• 2002

Non-linear large-displacement elasto-plastic finite element analyses are used to propose design recommendations for the eaves bracket of a cold-formed steel portal frame. Owing to the thinness of the sheet steel used for the brackets, such a structural design problem is not trivial as the brackets need to be designed against failure through buckling; without availability of the finite element method, expensive laboratory testing would therefore be required. In this paper, the finite element method is firstly used to predict the plastic moment capacity of the eaves bracket. Parametric studies are then used to propose design recommendations for the eaves bracket against two potential buckling modes of failure: (1) buckling of the stiffened free-edge into one-half sine wave, (2) local plate buckling of the exposed triangular bracket area.The results of full-scale laboratory tests on selected geometries of eaves bracket demonstrate that the proposed design recommendations are conservative. The use of the finite element method in this way exploits modern computational techniques for an otherwise difficult structural design problem.

• 한국항공우주학회지
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• 제38권11호
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• pp.1115-1122
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• 2010

본 논문에서는 샌드위치-적층판 단일겹침 접착 조인트의 정적강도를 시험을 통해 연구하였다. 접착제의 두께(3종류 : 0.2, 2, 4 mm)와 환경조건(2가지 : 상온, 고온흡습)을 변화시키면서 총 38개의 시편을 제작하여 시험을 수행하였다. 시험 결과, 접착제의 두께가 0.2mm에서 2 mm 와 4 mm로 증가함에 따라 체결부의 파손강도가 각각 16% 와 30% 정도 감소하는 것으로 나타났다. 반면 고온흡습 환경에서의 파손강도는, 접착제의 두께가 0.2mm인 경우를 제외하면, 접착제의 열화현상이 적층판과 샌드위치 면재의 층간분리 혹은 층내분리 파손을 지연시켜, 상온건조 환경에 비해 약 12% 가량 높게 나타났다. 접착제의 두께가 얇은 0.2 mm의 경우 시험환경의 효과는 나타나지 않았다.