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Multi-body Dynamic Analysis for Tripod Constant Velocity Joint (트라이포드 타입 등속조인트의 다물체 동역학 해석)

  • Song, Myung-Eui;Lim, Young-Hun;Cho, Hui-Je;Bae, Dae-Sung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.1
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    • pp.1-7
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    • 2010
  • The paper proposes a multi-body dynamic simulation to numerically evaluate the generated axial force(G.A.F) and plunging resistant force(P.R.F) practically related to the shudder and idling vibration of an automobile. A numerical analysis of two plunging types of CV joints, tripod joint(TJ) and very low axial tripod joint(VTJ), is conducted using the commercial program DAFUL. User-defined subroutines of a friction model illustrating the contacted parts of the outboard and inboard joint are subsequently developed to overcome the numerical instability and improve the solution performance. The Coulomb friction effect is applied to describe the contact models of the lubricated parts in the rolling and sliding mechanisms. The numerical results, in accordance with the joint articulation angle variation, are validated with experimentation. The offset between spider and tulip housing is demonstrated to be the critical role in producing the 3rd order component of the axial force that potentially causes the noise and vibration in vehicle. The VTJ shows an excellent behavior for the shudder when compared with TJ. In addition, a flexible nonlinear contact analysis coupled with rigid multi-body dynamics is also performed to show the dynamic strength characteristics of the rollers, housing, and spider.

Test Result on Embedded Steel Column-to-Foundation Connection for Modular Unit Structural System (유닛 모듈러 기둥 매입형 기초 접합부에 대한 실험 연구)

  • Lee, Sang Sup;Bae, Kyu Woong;Park, Keum Sung;Hong, Sung Yub
    • Journal of Korean Society of Steel Construction
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    • v.26 no.6
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    • pp.537-547
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    • 2014
  • A steel modular unit structural system has been used increasingly for mid and high-rise buildings, since the building can be easily constructed by assembling the pre-made modular unit structures. For this structural system, each modular unit structures have to be properly connected to the foundation to transfer the axial force and the bending moment that are generated from external load to the ground. In this study, a new type of the embedded steel column-to-foundation connection was proposed, and its flexural behavior was evaluated through a series of experimental study. Five full scale specimens for the proposed connections were constructed and tested. The effect of the main parameters that affect the flexural behavior of the proposed connection, such as embedment length and shape of end plate, were studied. From the results, it was found that the flexural stiffness of the proposed connection was higher than that of the semi-rigid connection for all test specimens, and 200 mm of embedment length was proper for the given test specimens in this study.

Parametric Design of Contact-Free Transportation System Using The Repulsive Electrodynamic Wheels (반발식 동전기 휠을 이용한 비접촉 반송 시스템의 변수 설계)

  • Jung, Kwang Suk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.3
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    • pp.310-316
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    • 2016
  • We propose a novel contact-free transportation system in which an axial electrodynamic wheel is applied as an actuator. When the electrodynamic wheel is partially overlapped by a fixed conductive plate and rotates over it, three-axis magnetic forces are generated on the wheel. Among these forces, those in the gravitational direction and the lateral direction are inherently stable. Therefore, only the force in the longitudinal direction needs to be controlled to guarantee spatial stability of the wheel. The electrodynamic wheel consists of permanent magnets that are repeated and polarized periodically along the circumferential direction. The basic geometric configuration and the pole number of the wheel influence the stability margin of a transportation system, which would include several wheels. The overlap region between the wheel and the conductive plate is a dominant factor affecting the stiffness in the lateral direction. Therefore, sensitivity analysis for the major parameters of the wheel mechanism was performed using a finite element tool. The system was manufactured based on the obtained design values, and the passive stability of a moving object with the wheels was verified experimentally.

Bending Behavior of the Mooring Chain Links Subjected to High Tensile Forces (강한 인장 상태에서의 계류 체인 링크의 휨 거동)

  • Kim, Seungjun;Won, Deok-Hee
    • Journal of Korean Society of Steel Construction
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    • v.29 no.2
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    • pp.99-110
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    • 2017
  • This paper presents the study of the bending behavior of mooring chain links for keeping the position of the offshore floating structures. In general, chain links have been thought as the axial members due to the fundamental boundary condition. But, the flexural stiffness can be induced to the contact surface between chain links when friction occurs at the surface of the chain links due to high tensile force. Especially, the mooring chains for offshore floating platforms are highly tensioned. If the floater suffers rotational motion and the mooring chain links are highly tensioned, the rotation between contact links, induced by the floater rotation, generates the bending moment and relevant stresses due to the unexpected bending stiffness. In 2005, the mooring chain links for the Girassol Buoy Platform were failed after just 5 months after facility installation, and the accident investigation research concluded the chain failure was mainly caused by the fatigue due to the unexpected bending stress fluctuation. This study investigates the pattern of the induced bending stiffness and stresses of the highly tensioned chain links by nonlinear finite element analysis.

An Analytical Study on the behavior of the Pier considering Soil Conditions (지반 조건을 고려한 잔교의 거동에 관한 해석적 연구)

  • Sin, Ha Myung;Yoon, Gi Yong;Park, Jong Sup
    • 한국방재학회:학술대회논문집
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    • 2011.02a
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    • pp.214-214
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    • 2011
  • 최근 국내 연안역에는 관광의 활성화 등의 목적으로 잔교가 많이 가설되고 있다. 그러나 잔교의 설계에 대한 규정이 없어 현재는 항만 및 어항설계기준을 준용하여 설계하고 있는 실정이며, 또한 지역적 특성을 반영하지 못하고 건설되어 과다한 단면을 사용하는 경우가 많고, 경제성이나 경관성을 갖추지 못한 경우가 많은 실정이다. 본 연구에서는 합리적인 잔교용 설계기준을 마련하기 위한 기초적인 연구로써 지반조건을 고려한 잔교의 거동특성을 분석하고자 하였다. 이를 위하여 해석모델을 개발하고, 다양한 해석조건에 대한 해석을 수행하여 그 특성을 정리하고자 하였다. 이를 통하여 잔교의 합리적인 구조시스템을 개발하고, 설계기준을 정리하는데 이바지 하고자 한다. 이 연구에서는 서해안의 연약지반을 고려하기 위해 지반스프링을 이용한 해석모델을 개발하고, 다양한 해석조건에 대한 해석을 수행하여 그 특성을 파악하고자 하였다. 조립식 잔교는 Capbeam, Wood Deck, ㄱ형강, Pile로 네 가지의 구성으로 이루어지고, 이 네 가지 요소의 재료는 강재로 사용하였으며, 하중에 대해서는 항만 및 어항설계기준을 준용하여 군중하중 $5kN/m^2$, 월파력 $20.1kN/m^2$을 사용하였고, 풍하중은 도로교 설계기준을 이용하여 산정한 $3.309kN/m^2$을 사용하였다. 재하하중 및 하중에 대한 최적단면에 대한 연구를 활용하여 본 연구에서는 지반조건의 영향, Capbeam과 Pile의 크기변화, 사항 등의 영향을 고려하였을 때 각 구성요소에서 발생하는 단면력의 변화와 축력, 접합부 모멘트 등의 외력과 내력을 정리하여 잔교의 거동특성을 파악하고자 하였다. 다양한 변수해석을 수행하기 위하여 지반조건을 고려한 2D 해석모델을 개발하였으며, 본 연구에서 고려한 군중하중, 풍하중, 월파력의 설계하중 중에서는 월파력이 지배적인 것을 알 수 있었다. Pier의 지름이 증가 하면 작용하는 월파력이 커지고 따라서 단면력이 증가하는 것을 알 수 있었다. 그러므로 합리적인 Pier의 크기 결정이 경제적이고 경관이 우수한 잔교 건설에 중요 요인임을 알 수 있다. 본 연구는 잔교의 설계기준 정립에 기초자료로 활용할 수 있을 것으로 판단되나, 보다 합리적인 잔교의 설계와 시공을 위해서는 지속적인 연구가 필요한 것으로 판단된다.

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Behavior of tunnel under the influence of pre-loading on braced wall during the adjacent ground excavation (근접굴착 시 벽체에 선행하중 재하에 따른 터널의 거동)

  • Kim, Il;Lee, Sang-Duk
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.4
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    • pp.331-341
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    • 2007
  • Pre-loads could be imposed on the braced wall to prevent the horizontal displacements during the ground excavation adjacent to the existing tunnel. For this purpose, new pre-loading system through which large pre-loads could be applied to the braced wall was used in the model tests. Large scale model tests were performed in the real scale test pit which was 2.0 m in width and 6.0 m in hight and 4.0 m in length. Test ground was constructed by sand. Model tunnel in 1.2 m diameter was constructed before test ground excavation. Test ground was excavated adjacent to existing tunnel and was braced. To investigate the effect of pre-loading, tests without pre-load were also performed. During the ground excavation were the behavior of braced wall, test tunnel, and ground measured. Model tests were also numerically analysed and their results were compared to that of the real scale tests. As a result, it was found that the stability of the existing tunnel was greatly enhanced when the horizontal displacements of braced wall was reduced by applying pre-load larger than the design load.

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An Experimental Study on Structural Performance of SFRC filled Built-up Square Columns (강섬유 콘크리트가 충전된 용접조립 각형강관 기둥의 구조성능 실험연구)

  • Kim, Sun Hee;Yom, Kong Soo;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.27 no.1
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    • pp.13-22
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    • 2015
  • This study suggests mixing steel fibers in concrete to secure the toughness of the columns. Therefore, to evaluate the structural behavior of welded built-up square columns filled with steel fiber reinforced concrete, ten stub column specimens were fabricated for compressive loading test with variables of steel fiber mixing ratio and loading condition. It is deduced that the steel fibers continue to provide tensile strength even after the concrete cracks and thus improve the strength and behavior of the column when bending moment is applied to it. A small amount of steel fibers can improve compressive strength and bending strength and thus produce economically efficient results when employed in structural design.

Development of Abutment-H pile Connection for Large Lateral Displacements of Integral Abutment Bridges (일체식 교대 교량의 대횡변위를 위한 교대와 H형 말뚝 연결부의 개발)

  • Kim, Woo Seok;Lee, Jaeha;Park, Taehyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.4
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    • pp.309-318
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    • 2013
  • Abutment-to-pile connection in an integral abutment bridge is vulnerable to lateral displacement induced by thermal movement of the superstructure. However, previous researches have merely focused on the connection. In order to improve the performance of the connection, new abutment-to-pile connection designs were proposed based on quasi-static nonlinear finite element model. The reinforcement detail specified in PennDOT DM4 and HSS tube were barely effective in controlling crack growing but spiral rebar effectively performed to delay crack growth as well as absorbing energy capacity. However, it was found that delaying cracking and strengthening the connection also caused the high lateral load in superstructures. Consequently, shape of HP pile were modified to introduce plastic hinge of the HP pile for reducing the lateral load in superstructures. Connections with modified HP pile significantly prevented crack propagations under the lateral displacement.

Simplified Moment-Curvature Relationship Model of Reinforced Concrete Columns Considering Confinement Effect (구속효과를 고려한 철근 콘크리트 기둥의 모멘트-곡률 관계 단순모델)

  • Kwak, Min-Kyoung;Yang, Keun-Hyeok
    • Journal of the Korea Concrete Institute
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    • v.28 no.3
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    • pp.279-288
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    • 2016
  • The present study simplified the moment-curvature relationship to straightforwardly determine the flexural behavior of reinforced concrete (RC) columns. For the idealized column section, moments and neutral axis depths at different stages(first flexural crack, yielding of tensile reinforcing bar, maximum strength, and 80% of the maximum strength at the descending branch) were derived on the basis of the equilibrium condition of forces and compatibility condition. Concrete strains at the extreme compression fiber beyond the maximum strength were determined using the stress-strain relationship of confined concrete, proposed by Kim et al. The lateral load-displacement curves converted from the simplified moment-curvature relationship of columns are well consistent with test results obtained from column specimens under various parameters. The moments and the corresponding neutral axis depth at different stages were formulated as a function of longitudinal reinforcement and transverse reinforcement indices and/or applied axial load index. Overall, curvature ductility of columns was significantly affected by the axial load level as well as concrete compressive strength and the amount of longitudinal and transverse reinforcing bars.

Slip Behavior of Friction Type High-Tension Bolted Joints with Oversize Hole (과대공을 갖는 고장력 볼트 마찰이음부의 미끄러짐 거동)

  • Cho, Sun Kyu
    • Journal of Korean Society of Steel Construction
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    • v.9 no.3 s.32
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    • pp.301-307
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    • 1997
  • In field fabrication of steel members, the oversize hole is frequently required due to reaming and mismatching. But, there are no provisions and investigations about oversize hole in the Korean specifications. So, in this study, the tension test of friction type high-tention bolted joints is performed with parameters of bolt hole size, surface treatment and tightening force, and investigate the effect of slip behavior with those parameters. From the results, the enough tightening force is needed to obtain some degree slip load in shot blast treatment case, although tightening force is reduced somewhat, it is no problem to guarantee slip load in zincrich primer case. The slip behavior of joints with oversize hole(26mm) is similar to the slip behavior of joints with hole of nominal size.

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