• 한국산학기술학회논문지
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• 제16권11호
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• pp.7870-7877
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• 2015

장대레일 궤도가 철도교량 상에 위치하는 경우, 교량과 궤도의 상호작용에 의해 레일에 발생하는 축력분포가 복잡해지며 부가축력이 발생하여 토노반상 장대레일에 비해 큰 축력이 레일에 발생된다. 이로 인해 교량상에 부설되는 궤도는 교량과의 상호작용 영향을 최소화하여 궤도와 주행열차의 안전성을 추가로 확보하여야 한다. 국내 철도설계지침 및 편람 KRC-08080(궤도-교량 종방향 상호작용 해석)에서는 상호작용의 주요 변수인 레일체결장치의 종방향 저항(마찰거동) 물성치가 유럽기준을 적용하여 특정 수치로 규정되어 있으나, 국내 철도에 적용하기 위해서는 실제 사용되는 체결장치의 성능 특성을 반영한 검토가 필요하다. 본 논문에서는 국내 교량상 콘크리트 궤도에 적용되는 레일체결장치의 마찰거동 실험을 수행하였으며, 이로부터 체결장치의 물성치에 대한 통계적 특성을 분석하였다.

• Steel and Composite Structures
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• 제20권2호
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• pp.251-266
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• 2016

The paper combines two distinct parts. First the behavior of welded headed studs with small diameters of 10 and 13 mm acting as shear connectors (which are not embraced in current standards) is studied. Based on standard push tests the load-slip relationships and strengths are evaluated. While the current standard (Eurocode 4 and AISC) formulas used for such studs give reasonable but too conservative strengths, less conservative and full load-slip rigidities are evaluated and recommended for a subsequent investigation or design. In the second part of the paper the partially encased beams under bending are analyzed. Following former experiments showing rather indistinct role of studs used for shear connection in such beams their role is studied. Numerical model employing ANSYS software is presented and validated using former experimental data. Subsequent parametric studies investigate the longitudinal shear between steel and concrete parts of the beams with respect to friction at the steel and concrete interface and contribution of studs with small diameters required predominantly for assembly stages (concreting). Substantial influence of the friction and effect of concrete confinement was observed with rather less noticeable contribution of the studs. Distribution of the longitudinal shear and its sharing between friction and studs is presented with concluding remarks.

• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.39-46
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• 2023

이 연구에서는 차세대 고속철의 증가하는 주행속도에 따라 600 km/h 까지 10 km/h 간격으로 고속철 PSC 박스 연속교량의 교량받 침에 대한 동적거동을 수치해석하였다. 경부 고속철 구간의 40미터 단경간과 2경간 연속 PSC 박스교를 연구대상으로 프레임모형을 구성하였 으며, 38자유도의 관성질량 차량모형 및 교량과 궤도의 불규칙성을 포함한 상호작용력을 고려하였다. 주행속도별 교량받침의 종방향 변위와 누적이동거리와 변위속도를 산정하여 교량의 동적거동 추이분석과 비교하였다. 또한 마찰판의 내구성능평가를 위한 장기마찰시험 기준을 적 용하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.483-491
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• 1997

The purpose of this study id to define the behavior of the girder ledge of precast girder-beam joint in Frame Type Precast Concrete Construction Method. And in behavior, girder ledge is different with bracket, because of longitudinal effective width and longitudinal bending. specif c objectives of this study are followed: $\circled1$ To investigate the effects of concrete compressive strength on the maximum shear strength of girder ledge, $\circled2$ To investigate the effects of the shear-span ratio and effective area on behavior of girder ledge, $\circled3$ To investigate the effects of the types of reinforcement on behavior and maximum shear strength of girder ledge, $\circled4$ To study the applicable possibility of the suggested shear friction formulas to estimating the shear strength of girder ledge.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.103-109
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• 2008

Semi-spherical CVT(SS-CVT) is one of friction drives, which transmits power via the friction force between a spherical shaped variator and output disks. The variator varies the speed ratio of SS-CVT continuously as well as transmits input power into the output shaft. Therefore two friction forces are normally applied on the variator; one is the longitudinal friction force for power transmission and the other is the lateral for shifting. In order to investigate the dynamic behavior of SS-CVT, we introduced a numerical model of 2-dimensional friction force using a function of slip ratio and slip angle. And a dynamic model, which describes the shifting mechanism of SS-CVT, is developed through 3-dimensional vector analysis. Finally we presented numerical results of the shift characteristics focused on the transient behavior of the variator's slip ratio and slip angle. The numerical results also show the typical CVT shifting characteristics of SS-CVT and stable shifting behaviors of the variator.

• Tribology and Lubricants
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• 제5권2호
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• pp.94-100
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• 1989

Friction and Wear behavior of continuous graphite fiber composites was studied for different fiber orientations against the sliding direction. The effect of fiber orientation on friction and wear of the composite and on the deformation of the counterface was investigated experimentally. Pin on disk type testing machine was built and employed to generate the friction and wear data. A graphite fiber composite plate was produced by the bleeder ply molding in an autoclave and machined into rectangular pin specimens with specific fiber orientations, i.e., normal, transverse, and longitudinal directions. Three different wear conditions were employed for two different periods of time, 24 and 48 hours. The wear track of the worn specimens and the metal counterface was examined with a scanning electron microscope (SEM) to observe the damaged fibers on the surface and wear film generation on the counterface. Wear mechanism of the composite during sliding wear is proposed based on the experimental results.

• Journal of Welding and Joining
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• 제30권2호
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• pp.47-53
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• 2012

This paper aimed to study and understand the mechanical phenomena of thermal elasto-plastic behavior on the dissimilar butt joint (Al 6061-T6 and STS304) by TIG assisted Friction Stir Welding. Heat conduction and residual stress analysis is carried out using in-house solver. Two-dimensional results of the heat distribution and residual stresses in dissimilar joint for particular tool geometry and material properties are presented. The predicted stress along longitudinal direction in Al 6061-T6 and STS304 are approximately between 12-15% of their respective yield strengths. A comparison is made between experimentally measured and numerically predicted equivalent residual stress values.

• 한국도로학회논문집
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• 제12권3호
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• pp.139-146
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• 2010

본 연구는 포스트텐션 콘크리트 포장(PTCP: Post-Tensioned Concrete Pavement)에 고속축중계(WIM: Weigh-in-Motion)를 설치한 포장 시스템의 거동을 분석하기 위하여 수행되었다. PTCP는 일차로 폭으로 기존의 아스팔트 포장을 절삭하여 제거한 후에 시공되었다. PTCP는 슬래브의 연장이 길기 때문에 긴장을 통해 프리스트레스를 적절히 작용시키기 위해서는 슬래브와 하부층과의 마찰이 적어야 하며 이러한 영향을 시험시공을 통해 우선적으로 분석하였으며, 환경하중에 따른 슬래브의 종방향 거동도 분석하였다. 시험시공을 통해 얻은 결과를 바탕으로 공용중인 도로에 WIM 센서를 설치한 PTCP를 시공하였으며 이러한 포장체가 환경하중을 받을 때의 컬링 거동을 측정하여 특성을 분석하였다. 연구결과 PTCP 슬래브 상부의 일부를 절삭하여 WIM 센서를 설치하더라도 PTCP의 거동은 이에 영향을 받지 않는 것을 알 수 있었으며, WIM 센서의 정밀 측정에 부합되는 PTCP 시스템을 시공할 수 있는 기반을 마련하였다.

• Smart Structures and Systems
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• 제30권5호
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• pp.479-500
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• 2022

In this study, a new type of isolation bearing is proposed by combining S-shaped steel plate dampers (SSDs) with a spherical steel bearing, and the seismic control effect of a five-span standard high-speed railway bridge is investigated. The advantages of the proposed S-shaped steel damping friction bearing (SSDFB) are that it cannot only lengthen the structural periods, dissipate the seismic energy, but also prevent bridge unseating due to the restraint effectiveness of SSDs in the large relative displacements between the girders and piers. This study first presents a detailed description and working principle of the SSDFB. Then, mechanical modeling of the SSDFB was derived to fundamentally define its cyclic behavior and obtain key mechanical parameters. The numerical model of the SSDFB's critical component SSD was verified by comparing it with the experimental results. After that, parameter studies of the dimensions and number of SSDs, the friction coefficient, and the gap length of the SSDFBs were conducted. Finally, the longitudinal seismic responses of the bridge with SSDFBs were compared with the bridge with spherical bearing and spherical bearing with strengthened shear keys. The results showed that the SSDFB can not only significantly mitigate the shear force responses and residual displacement in bridge substructures but also can effectively reduce girder displacement and prevent bridge unseating, at a cost of inelastic deformation of the SSDs, which is easy to replace. In conclusion, the SSDFB is expected to be a cost-effective option with both multi-stage energy dissipation and restraint capacity, making it particularly suitable for seismic isolation application to high-speed railway bridges.

• Structural Engineering and Mechanics
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• 제78권2호
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• pp.163-174
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• 2021

Track-bridge interaction has become an essential part in the design of bridges and rails in terms of modern railways. As a unique ballastless slab track, the longitudinal continuous slab track (LCST) or referred to as the China railway track system Type-II (CRTS II) slab track, demonstrates a complex force mechanism. Therefore, a comprehensive track-bridge interaction study between multi-span simply supported beam bridges and the LCST is presented in this work. In specific, we have developed an integrated finite element model to investigate the overall interaction effects of the LCST-bridge system subjected to the actions of temperature changes, traffic loads, and braking forces. In that place, the deformation patterns of the track and bridge, and the distributions of longitudinal forces and the interfacial shear stress are studied. Our results show that the additional rail stress has been reduced under various loads and the rail's deformation has become much smoother after the transition of the two continuous structural layers of the LCST. However, the influence of the temperature difference of bridges is significant and cannot be ignored as this action can bend the bridge like the traffic load. The uniform temperature change causes the tensile stress of the concrete track structure and further induce cracks in them. Additionally, the influences of the friction coefficient of the sliding layer and the interfacial bond characteristics on the LCST's performance are discussed. The systematic study presented in this work may have some potential impacts on the understanding of the overall mechanical behavior of the LCST-bridge system.