• Title/Summary/Keyword: fastener

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Parametric Analysis for Up-lifting force on Slab track of Bridge under Train Load (열차하중 재하시 교량상slab궤도의 상향력 민감도분석)

  • Choi, Sung-Ki;Park, Dae-Geun;Han, Sang-Yun;Kang, Young-Jong
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.279-282
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    • 2008
  • The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of the end rotation of the overhang due to the vertical load. When the up-lifting force exceeds the clamp force of the fastener clip, the rail pad is out of fastener, which makes decrease the serviceability of the railway, such as noise and vibration. Furthermore, it is possible to reduce the safety of the track as the longitudinal resistance. This study is focused on guideline suggestion to decrease up-lifting force in the fastener adjacent to the civil joint of slab track of bridge throughout the parametric analysis between the vertical spring stiffness of the fastener as the material approach, the space of fastener adjacent to bridge transition, the rigidity of the girder as the geometrical approach and up-lifting force under the train load.

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Parameteric Analysis for Up-lifting force on Slab track of Bridge (교량상 slab궤도의 상향력 민감도분석)

  • Choi, Sung-Ki;Park, Dae-Geun;Han, Sang-Yoon;Kang, Young-Jong
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1188-1195
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    • 2007
  • The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads, the settlement of supports, and the temperature gradients. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of various load cases, such as the end rotation of the overhang due to the vertical load, the bending of pier due to acceleration/braking force and temperature deviation, the settlement of embankment and pier, the temperature deviation of up-down deck and front-back pier, and the rail deformation due to wheel loads. The analysis of the rail fastener is made to verify the superposed tension forces in the rail fastener due to various load cases, temperature gradients and settlement of supports. The potential critical fasteners with the highest uplift forces are the fastener adjacent to the civil joint. The main influence factors are the geometry of the bridge such as, the beneath length of overhang, relative position of bridge bearing and fastener, deflection of bridge and the vertical spring stiffness of the fastener.

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A study on the shape design and analysis of rail fastener (레일 체결구의 형상설계 및 해석 기술에 관한 연구)

  • 이지하;나성훈;양신추;임영락
    • Proceedings of the KSR Conference
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    • 1999.11a
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    • pp.447-454
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    • 1999
  • In this paper, a technique for the shape design and analysis of rail fastener is presented. KRRI's own 3 type fasteners are developed after due consideration for tile aspects of installation, maintenance, and cost of fastener. Numerical by using commercial FEM program COSMOS/Works are carried out to determine the optimal shape of fastener clip. Front tile manufactured models and numerical results, the developed fasteners show tile possibility to be commercialized. But in order to have their competitiveness on the markets, further studies are required for the demonstration of performance through laboratory and field tests

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Experimental investigation of a prefabricated timber-concrete composite floor structure: Notched-slab approach

  • Yilmaz, Semih;Demir, Serhat;Vural, Nilhan
    • Advances in concrete construction
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    • v.12 no.1
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    • pp.13-23
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    • 2021
  • This study presents the experimental performance of a high ductility and energy dissipation capacity connector named notched-slab fastener, which is developed for timber-concrete composite floor structures. Notched-slab fastener is unique because the notch was left in the concrete slab instead of a timber beam for the first time. In this way, cross-section loss in the timber beam is prevented. This is one of the most important benefits of the proposed connector. Experimental performance of the purposed connector was investigated with two test methods: push-out test and bending test. For comparison purposes, a notched fastener was also produced and tested as reference sample. Test results showed that notched-slab fastener has stable load carrying behavior under push-out loading with high-energy dissipation and no sudden strength degradation. In addition, notched slab design provided moment arm to the fastener and the damage is concentrated in the connector instead of concrete.

Effective Methods Reducing Joint Vibration and Elongation in High speed Rail Bridge (고속철도교 신축부의 진동 및 신축의 효율적인 저감 방안)

  • Min, Kyung-Ju;Kang, Tae-Ku;Lim, Nam-Hyoung
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.800-806
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    • 2011
  • Thermal expansion which occurs at the high speed rail joint is proportional to the free length from the point of fixity. This thermal expansion behaves similar to free expansion because the girder longitudinal stiffness is much larger than longitudinal resistance of rail pads. But the longitudinal displacement in the long rail is nominal because the longitudinal support condition of the girder is normally MFM(movable-fix-movable) system. Due to these girder expansion characteristics, there is longitudinal relative displacement at the rail pad and rail fastener spring which connects rail and girder. If the relative displacement between rail and girder is beyond the elastic limit for the rail pad, rail fastener system shall be applied using sliding fastener to prevent rail pad damage and fastener separation resulting from slip. On the other hand, train vertical vibration and tilting can occur due to the lack of fastener vertical force if the sliding fastener is applied at the girder joint. In the high speed rail bridge, vibration can occur due to the spring stiffness of the elastomeric bearing, also both vertical downward and upward displacement can occur. The elastomeric bearing vertical movement can cause rail displacement and finally the stability of the ballast is reduced because the gravel movement is induced.

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On effects of rail fastener failure on vehicle/track interactions

  • Xu, Lei;Gao, Jianmin;Zhai, Wanming
    • Structural Engineering and Mechanics
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    • v.63 no.5
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    • pp.659-667
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    • 2017
  • Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.

Seoul National University of Science and Technology (칼라 나사 검사를 위한 표면 영역 자동 검출)

  • Song, Tae-Hoon;Ha, Jong-Eun
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.1
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    • pp.107-112
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    • 2016
  • Fastener is a very important component that is used in various areas in industry. Recently, various color fasteners are introduced. According to this, online inspection is required in this area. In this paper, an algorithm for the automatic extraction of the surface of color fastener using color information and dynamic programming is presented. The outer boundary of fastener is found using the difference of color that enables robust processing. The inner boundary of fastener is found by dynamic programming that uses the difference of brightness value within fixed area after converting image to polar coordinate. Experiments are done using the same parameters.

Application of Weight Function Method to Elliptical Arc Through Cracks at Mechanical Fastener Holes (기계적 체결홀에 존재하는 타원호형 관통균열에 대한 가중함수법의 적용)

  • Heo, Sung-Pil;Yang, Won-Ho;Chung, Ki-Hyun;Hyun, Cheol-Seung
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.304-310
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    • 2001
  • Cracks at mechanical fastener holes usually nucleate as elliptical comer cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks after penetrating the opposite surface. In this study mode I, II and III stress intensity factors at two surface points of elliptical arc through cracks at mechanical fastener holes are analyzed by applying weight function method. The weight function method for two dimensional mixed-mode problem is extended to three dimensional one and it is verified.

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Rational designing of double-sided nail plate joints using the finite element method

  • Zhou, Tinozivashe;Guan, Z.W.
    • Structural Engineering and Mechanics
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    • v.28 no.2
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    • pp.239-257
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    • 2008
  • Double-sided punched metal plate timber fasteners present projections on both sides, which offer improved joint fire resistance and better joint aesthetics. In this paper, 3-D nonlinear finite element models were developed to simulate double-sided nail plate fastener timber joints. The models, incorporating orthotropic elasticity, Hill's yield criterion and elasto-plasticity and contact algorithms, are capable of simulating complex contact between the tooth and the timber and between the base plate and the timber in a fastener. Using validated models, parametric studies of the double-sided nail plate joints was undertaken to cover the tooth length and the tooth width. Optimal configuration was assumed to have been attained when increase in nail plate tooth width did not result in a raise in joint capacity, in conjunction with the optimum tooth length. This paper presents the first attempt to model and optimise tooth profile of double-sided nail plate fastener timber joints, which offers rational designs of such fasteners.

A Study on Setting Quality Level of Fastener Tape for Military Textile Products (군용 섬유제품에 적합한 파스너 테이프의 품질수준 연구)

  • Kim, Seongwook;Lee, Minhee;Hong, Seongdon;Lee, Jung-Soon
    • Textile Coloration and Finishing
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    • v.29 no.3
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    • pp.162-170
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    • 2017
  • Fastener tapes are widely used as auxiliary materials in textile products, and military textiles products are also applied. However, in Korea, the HL3-WA class of KS K 1309 was applied to military uniforms without consideration of the operating environment. Instead of adopting the standard of initial strength for Korean military uniforms, the US military applied the value after 3 washings, and presented different properties according to the items. Also in Japan, the standard was applied differently according to products in general clothing. The purpose of this study in to examine the quality level of fastener tapes used for military materials. The changes of tensile shear strength and peel strength of military and commercial fastener tape were studied after washing. As a result, the initial strength of the current military fastener tapes was higher than commercial one, but the strength retention rate was rapidly decreased as the number of washing. So it was confirmed that the decrease in strength was relatively lower than commercial one. It is necessary to improve the durability by adjusting the adhesive strength to suit the purpose of the product, and it is necessary to consider the priority of maintaining the durability according to the initial performance and repeated use according to the use environment, respectively.