• Title, Summary, Keyword: 미끄러짐 계수

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Experimental Study on the Slip Coefficient with Member Type and Dimensions of High Tension Bolt Hole (부재 및 고장력볼트 구멍치수에 따른 미끄러짐계수의 실험적 연구)

  • Yang, Seung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.9
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    • pp.4277-4283
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    • 2012
  • Slip coefficient, whose value is dependent on the condition of contact surface at the friction joint of high tension bolt, is determined by slip load. Because contact area affects slip load, contact area that varies with bolt hole size is also related to the slip coefficient. In this study, we manufactured 32 specimens and performed bending and tension tests in order to examine changes in slip coefficient and load with material type, bolt diameter, and size of bolt hole. Slip load of specimens with oversize bolt hole had strength that was more than 80% higher than the slip load of specimens with standard bolt hole, and it also exceeded the design slip strength. In addition, we observed significant correlation between net-section ratio and slip ratio of specimens with oversize and standard bolt hole. However, some differences between the specimens are thought to have been caused by reduction in initial axial force of high tension bolt, which is an important parameter of slip coefficient. It is self-evident that increased bolt hole size would lead to decrease in design strength as it reduces both slip coefficient and bolt axial force. Nevertheless, we suggest that some flexibility in regulation of bolt hole, as long as it does not threaten the structural stability, may be a positive factor in terms of workability and efficiency.

A Study on the Slip Behavior of Coated High Tension Bolted Joints (도장처리한 고장력볼트 연결부의 미끄러짐 특성에 관한 연구)

  • Kyung, Kab Soo;Lee, Seung Yong;Kim, Ki Hyun
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.5A
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    • pp.691-697
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    • 2008
  • Coating the high tension bolted frictional joint has been generally allowed for anti-corrosion purpose. However in case of painting on paying surface of the high tension bolt, the influence on a slip strength of the joint depending on precision of painting has remained controversial. The study thus was intended to identify the slip behavior on high tension bolted frictional joint when applying ceramic painting, which has been currently developed. A slip test was conducted on a high tension bolted frictional joint specimen on which ceramic painting has been applied and a slip load and slip coefficient were measured. Based on result, the safety and usability of ceramic painting-applied high tension bolted frictional joint was evaluated. As a result, a difference to some extent by specimen in terms of load-displacement when a slip occurred was observed but an average slip coefficient appeared to have exceeded 0.4, which is the design frictional coefficient set forth in the specification. To secure the safety and usability of ceramic painting-applied high tension bolted frictional joint, it's necessary to establish the standard for painting as well as to revise the relevant specification.

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Sliding Conditions at the Interface between Soil and Underground Structure (지반과 지하구조물 경계의 미끄러짐 조건에 관한 연구)

  • 김대상
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.1
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    • pp.7-11
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    • 2002
  • By focusing on the resonant vibration mode of soil-underground structure system, this paper obtained dynamic soil stiffness and easy sliding conditions at the interface between soil and underground structure. Multi-step method is employed to isolate two primary causes of soil-structure interaction. Mohr-Coulomb criterion is used to determine the threshold level of the sliding. To find out the conditions the interface slides easily, parametric studies are performed about the factors governing sliding, which are the size and location of underground structures, ground condition, the configuration of surface deposit and interface friction coefficients.

A Study on Rational Design and Construction of High-Tension-Bolt Friction Joints (고장력볼트 마찰이음의 합리적 설계 및 시공에 관한 연구)

  • Lee, Seung Yong;Kyung, Kab Soo
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.3A
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    • pp.513-521
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    • 2006
  • Many studies have been conducted on the high tension bolt friction connection in the view of the field practice. Those effort, however, unfortunately have not been appropriately applied in the design specifications. Recently, particularly for steel bridges, rationalization of design takes greater attention from designers and hence, demand on rationalization of high tension connection becomes more significant. The purpose of this study is to suggest direction for the rationalization of high tension bolt connection and to also provide fundamental information for the improvement of the design specifications. In order to accomplish the purposes, the design specifications in Korea was analyzed and compared with other specification from abroad, and was studied one of the most important factors including slip coefficient, and the specifications on the size of bolt holes. The effect of over-sized bolt hole and the reduction of axial force on bolt was evaluated through the experimental studies on the slippage of the high tension bolt connections. Other research topics included herein includes the difference of slip coefficients, the effect of over-sized bolt holes and the gap distance of members, and the application of filler plate and corrosion protected bolts. From the research results, it is known that the specifications in Korea apply a constant slip coefficient with respect to the contacted surface conditions while various coefficients are available depending on the contacted surface conditions. Therefore, it is recommended that the specifications in Korea also develop and detail the slip coefficient which can appropriately take account of the variation of the contacted surface conditions. It is also suggested that the limitation abroad on the over-sized bolt hole may be applied for enhancing the effectiveness of construction.

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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
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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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Dynamic Interface Friction Behavior Between Soils and Construction Material(Steel) (조립토와 건설재료(steel)사이의 동마찰계수)

  • Kim, Dae-Sang
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.461-468
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    • 2001
  • 지진등에 의해 유발된 동 하중에 의한 지반-구조물 계의 응답은 지반-구조물사이의 경계에서의 마찰특성과 미끄러짐에 의해 크게 영향을 받게 된다 본 논문에서는 진동대(Shaking table)를 이용하여 조립토와 건설재료(Steel)의 경계에서 지반으로부터 지중구조물에 전달되는 전단응력 의 전달정도를 파악하기 위한 실험을 실시하였다. 본 실험에서 설정한 미끌어짐속도 범위내에서는 미끄러짐속도 변화에 따른 조립토와 건설재료(Steel)사이의 동마찰계수의 변화가 작다는 사실이 관찰되었다. 그리고 조립토의 평균유효입경의 변화가 동마찰계수에 미치는 영향도 함께 조사되었다. 또한 이 동마찰계수를 같은 조립토에 대한 평면변형률시험을 통해 얻어진 최대내부마찰각으로부터 구한 마찰계수와 비교하여 정량화하였다.

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Dynamic Friction Behavior of Interfaces Between Granular Materials and Steel (조립토와 건설재료(steel)사이의 동마찰계수)

  • 김대상
    • Journal of the Korean Geotechnical Society
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    • v.17 no.3
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    • pp.33-39
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    • 2001
  • 지진 등에 의해 유발된 동 하중에 의한 지반-구조물 계의 응답은 지반-구조물사이의 경계에서의 마찰특성과 미끄러짐에 의해 크게 영향을 받게 된다. 본 논문에서는 진동대(Shaking table)를 이용하여 조립토와 건설재료(steel)와의 경계에서 지반으로부터 지중구조물에 전달되는 전단응력의 전달정도를 파악하기 위한 실험을 실시하였다. 본 실험에서 설정한 미끄러짐속도 범위 내에서는 미끄러짐속도 변화에 따른 조립토와 건설재료(steel) 사이의 동마찰계수의 변화가 작다는 사실이 관찰되었다. 그리고 조립토의 평균유효입경의 변화가 동마찰계수에 미치는 영향도 함께 조사되었으며, 이 동마찰계수를 같은 조립토에 대한 평면변형률시험을 통해 얻어진 최대내부마찰각으로부터 구한 마찰계수와 비교하여 정량화하였다.

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Estimation of Safety and Economical Efficiency of Large High Tension Bolted Joints (대직경 고장력볼트 이음부의 안전성 및 경제성 평가)

  • Sung, Ki-Tae;Kyung, Kab-Soo;Lee, Seung-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.6
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    • pp.97-105
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    • 2009
  • This study was conducted for the purpose of examinating the safety and economical efficiency of large high tension bolted joints. The specimen using F10T-M30 large high strength bolts has been selected and static tensile test has been conducted to evaluate the slip characteristics. In addition, finite element analysis has been carried out to estimate the number of required bolts. As a result, the average slip coefficient of M30 high strength bolts exceeded 0.4 - the standard in highway bridge design specification - and has satisfied the slip strength, which is the same as that of M22 high strength bolts. In addition, if F13T-M22 high strength bolts were applied, the number of required bolts decreased by 21%, and if F10T-M30 high strength bolts were applied, the number of required bolts decreased by 46%, that leads to the conclusion that the economical efficiency in accordance with diametering of high strength bolts was now verified.

A Study on the Characteristics of High-Tension Bolted Joints' Behavior due to Surface Condition (표면상태에 따른 고장력볼트 마찰이음부의 거동특성에 관한 연구)

  • Cho, Sun Kyu;Hong, Sung Wook
    • Journal of Korean Society of Steel Construction
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    • v.9 no.3
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    • pp.421-430
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    • 1997
  • In this study, the static and the fatigue tests were performed with high tension bolted joints, of which the surfaces were spread with inorganic zinc-primer after shot-blast, and milling surface, and steel-natural surface, difference of friction surface condition were examined by comparing the esults of tests. From the result of synthetical investigation of this study. it is proper that using the torque management method in order to introduce design axial force to blots, and the provision of specifications that initial axial forces must be 110% of design axial forces is proper. Decreasing ratio of axial forces to initial force is proportional to common lorgarithms of time progress, it converge constant value after 20 hours, and decreasing ratio is little related to the roughness of friction surface. Sliding coefficient of milling, spreading inorganic zinc-primer, just producting is great in order and sliding forces are dependent on the applied axial forces, but if the applied axial forces are great, sliding coefficient become small by a loss of roughness. So it is confirmed that relation between the applied axial forces and the sliding forces are not proportional linearly. From the result of estimation on fatigue strength, all specimens satisfy the specifications with B-grade and milling surface is lower than the others about 14% in fatigue strength because in milling surface lose the function of friction-types joints at lower number of cycles. From the result of eximination for the distribution area of compressive force, friction area near to inside bolt is wider in the direction of stress than near to outside. It is guessed that this situation occurs because outside bolts firstly change from the friction connection to the bearing connection.

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Geomechanical Stability Analysis of Potential Site for Domestic Pilot CCS Project (국내 이산화탄소 지중격리저장 실증실험 후보부지의 역학적 안정성 평가 기초해석)

  • Kim, A-Ram;Kim, Hyung-Mok;Kim, Hyun-Woo;Shinn, Young-Jae
    • Tunnel and Underground Space
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    • v.27 no.2
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    • pp.89-99
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    • 2017
  • For a successful performance of Carbon Capture Sequestration (CCS) projects, appropriate injection conditions should be designed to be optimized for site specific geological conditions. In this study, we built a simple 2-dimensional analysis model, based on the geology of Jang-gi basin which is one of the potential sites of domestic CCS projects. We evaluated the impact of initial stress conditions and injection rate through coupled TOUGH-FLAC simulator. From the preliminary analysis, we constructed risk scenarios with the higher potential of shear slip and performed scenario analysis. Our analysis showed that normal stress regime produced the highest potential of shear slip and stepwise increasing injection rate scenario resulted in much larger pore pressure build up and consequent higher potential of the shear slip, which was evaluated using a mobilized friction coefficient.