• Title/Summary/Keyword: Tension Test

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A Development of Pulley-type Tensioning Device for a High Speed Railway (고속용 풀리형식 장력조정장치 개발)

  • Cho, Yong-Hyeon;Kwon, Sam-Young;Park, Young;Lee, Ki-Won
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.723-730
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    • 2006
  • In the electrical railway, the tension ascension of contact wire is essential to speed up of train and current collection performance of catenary largely depends on the tension. The tension variation rate of the tensioning device used in existing line limits within 5%, and the tension variation rate of the spring-type tensioning device installed at the section where tensioning length is short bounds within 15%. So it is urgent for us to localize it for high speed line, which the tension variation rate is limited within 3%. Therefore in this study, a pulley-type tensioning device for high speed line is developed. To verify the performance of developed device, a performance test, overload test and failure test is carried out under the code of the Kyung-Bu High Speed line. And it is secured durability performance through a fatigue test.

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Evaluation of Cumulative Damage of Pavement Concrete Using Split Tension Fatigue Test (쪼갬인장 피로시험 방법에 의한 포장용 콘크리트의 누적 손상 평가)

  • 윤병성;김동호;정원경;이봉학;윤경구
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.353-358
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    • 2002
  • The purpose of this paper was to estimate the cumulative damage of pavement concrete by split tension fatigue test. The split tension fatigue test of variable amplitude loading were performed in two and three stages. The results of the fatigue test by variable amplitude loading showed that the sums of damage were greater than 1 in the increasing sequence loading tests, and less than 1 in the decreasing sequence loading tests. The remaining life estimated by equivalent damage theory was almost similar to that of experimental results.

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Numerical simulation of tensile failure of concrete using Particle Flow Code (PFC)

  • Haeri, Hadi;Sarfarazi, Vahab
    • Computers and Concrete
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    • v.18 no.1
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    • pp.39-51
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    • 2016
  • This paper considers the tensile strength of concrete samples in direct, CTT, modified tension, splitting and ring tests using both of the experimental tests and numerical simulation (particle flow code 2D). It determined that which one of indirect tensile strength is close to direct tensile strength. Initially calibration of PFC was undertaken with respect to the data obtained from Brazilian laboratory tests to ensure the conformity of the simulated numerical models response. Furthermore, validation of the simulated models in four introduced tests was also cross checked with the results from experimental tests. By using numerical testing, the failure process was visually observed and failure patterns were watched to be reasonable in accordance with experimental results. Discrete element simulations demonstrated that the macro fractures in models are caused by microscopic tensile breakages on large numbers of bonded discs. Tensile strength of concrete in direct test was less than other tests results. Tensile strength resulted from modified tension test was close to direct test results. So modified tension test can be a proper test for determination of tensile strength of concrete in absence of direct test. Other advantages shown by modified tension tests are: (1) sample preparation is easy and (2) the use of a simple conventional compression press controlled by displacement compared with complicate device in other tests.

A Research on Dynamic Tension Response of Model Mooring Chain by Forced Oscillation Test (강제동요 시험을 이용한 모형 계류삭의 동적 응답 연구)

  • Kim, Hyun-Joe;Hong, Sa-Young;Hong, Sup;Cho, Suk-Kyu
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2002.10a
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    • pp.134-141
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    • 2002
  • A series of forced oscillation test on model mooring chain was carried out to investigate dynamic tension characteristics. The model test was conducted at two different water depth to gather basic data for 'truncated mooring test' and 'hybrid mooring test'. The truncated and hybrid mooring test are highly recommended to overcome the limitation of water depth in model test recently. The resultant tension RAO gives good possibility of approximation of dynamic tension by equivalent weight adjustment for the ratio of water depth in different water depth. Because the hybrid mooring test is the adequate combination of model test and simulation, accurate simulation model on mooring system is essential. The simulation results show good agreement with model test results.

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Field application of elasto-magnetic stress sensors for monitoring of cable tension force in cable-stayed bridges

  • Yim, Jinsuk;Wang, Ming L.;Shin, Sung Woo;Yun, Chung-Bang;Jung, Hyung-Jo;Kim, Jeong-Tae;Eem, Seung-Hyun
    • Smart Structures and Systems
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    • v.12 no.3_4
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    • pp.465-482
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    • 2013
  • Recently, a novel stress sensor, which utilizes the elasto-magnetic (EM) effect of ferromagnetic materials, has been developed to measure stress in steel cables and wires. In this study, the effectiveness of this EM based stress sensors for monitoring of the cable tension force of a real scale cable-stayed bridge was investigated. Two EM stress sensors were installed on two selected multi-strand cables in Hwa-Myung Bridge, Busan, South Korea. Conventional lift-off test was conducted to obtain reference cable tension forces of two test cables. The reference forces were used to calibrate and validate cable tension force measurements from the EM sensors. Tension force variations of two test cables during the second tensioning work on Hwa-Myung Bridge were monitored using the EM sensors. Numerical simulations were conducted to compare and verify the monitoring results. Based on the results, the effectiveness of EM sensors for accurate field monitoring of the cable tension force of cable-stayed bridge is discussed.

Extended Compliance Solution of ESET Specimen for Thermal fatigue Crack Growth Test (열피로 균열성장시험을 위한 ESET 시편의 확장된 컴플라이언스 해)

  • Lee, Ho-Jin;Kim, Maan-Won;Lee, Bong-Sang
    • Journal of the Korean Society of Safety
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    • v.20 no.1 s.69
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    • pp.62-67
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    • 2005
  • An eccentrically-loaded single edge crack tension specimen (ESET) is similar to a compact tension(CT) specimen loaded in tension-tension. The standard ESET specimen exhibits advantages over other types of cracked specimen, such as n, single-edge crack, and middle-crack tension specimen. The details of ESET specimen configuration, test procedure, and calculations are described in ASTM E647 standard. However, a difficulty in attaching COD gage to the knife-edge on the front foe of the specimen can be found when the size of ESET specimen is small for rapid cooling and heating in thermal fatigue testing. The finite element analysis is performed for the ESET specimen with projected knife-edge on the front foe and a crack-length-compliance equation is suggested for the new specimen configuration. Calibration test are conducted with 347 stainless steel to compare the measured crack length with the calculated crack length from the suggested compliance expression. The test results showed good agreements with those of analysis.

Experimental Study and Evaluation of Tension Stiffening Model in High Strength Concrete Beams (고강도 콘크리트 보에서 Tension Stiffening 모델을 이용한 실험적 연구 및 평가)

  • Shin, Dae Hwan;Jo, Eunsun;Kim, Min Sook;Kim, Heechuel;Lee, Young Hak
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.1
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    • pp.45-53
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    • 2014
  • In strength limit states design, it is assumed that after cracking, reinforcement carries all tension in the tension zone of reinforced concrete members. However, it can be seen the concrete between cracks will contribute to carrying a part of the tension stress in actual concrete members particularly at service load levels, this effect is referred as tension stiffening effect. In this study, tension stiffening models and high strength concrete beam flexural test results were verified through comparison. The relationship between moment-curvature and load-deflection was evaluated by result of tension stiffening model and test result values. The analysis results showed that ACI 318 and Owen & Damjanic generally shows good agreement.

Measurement of Retaining Tensile Load with the Relative Displacement Detector of Ground Anchors (상대변위측정기를 이용한 지반앵커의 보유인장력 측정)

  • Jeong, Hyeon-Sik;Han, Kwang-Suk;Lee, Yeong-Saeng
    • Journal of the Korean Geotechnical Society
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    • v.33 no.10
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    • pp.59-69
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    • 2017
  • The tension load of the ground anchor inserted in the ground gradually changes over time. In this regard the change of the initial tension load is primarily decreased by the fixation condition of the fixing head and the mechanical characteristics of the tensile material. The subsequent additional tension load is a time-dependent loss mostly due to the fixing conditions of the bonded length and the surrounding ground properties of the field. In this paper, therefore, a measurement system using a relative displacement detector that can relatively easily measure the change of tension load is discussed. As a result of the review, it was confirmed that the results using the relative displacement detector are similar to those of the real scale model test, and it was also confirmed that similar results were obtained with the result of the pull-out test conducted on the ground anchors fixed to weathered rocks condition. In addition, a pull-out test was conducted on the test anchors whose initial tension load loss was relatively large and through this test pull-out behavior of the tension type ground anchors was verified.

Difference of tension on mooring line by buoy type (부이 형상에 따른 부이줄 장력의 차이)

  • Lee, Gun-Ho;Kim, In-Ok;Cha, Bong-Jin;Jung, Seong-Jae
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.50 no.3
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    • pp.233-243
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    • 2014
  • The difference of mooring tension by type of buoy was investigated in the circulating water channel and the wave tank for deducting the most stable buoy from the current and the wave condition. 5 types of buoy made up of short cylinder laid vertically (CL-V), short cylinder laid horizontally (CL-H), capsule (CS), sphere (SP) and long cylinder (CL-L) were used for experiments. A mooring line and a weight were connected with each buoy. A tensile gauge was installed between a mooring line and a weight. All buoy's mooring tension was measured at the same time for the wave test with periods of 1.5~3.0 sec and wave heights of 0.1~0.3 m, and the current test with flow speeds of 0.2~1.0 m/sec. As a result, the order of tension value in the wave test was CL-H > CL-V > SP > CS > CL-L. In the current test CL-V and CL-H were recorded in the largest tension value, whereas SP has the smallest tension value. So it seems that SP buoy is the most effective in the location affected by fast current. CS is predicted to be suitable for a location that influence of wave is important more than that of current if practical use in the field is considered. And it was found that the difference of mooring tension among buoys in wave is related to the product of the cross sectional area and the drag coefficient for the buoy's bottom side in high wave height. The factor for the current condition was not found. But it was supposed to be related to complex factors like a dimension and a shape by buoy's posture to flow.

A Study on Elevated Temperature Fatigue Crack Growth Using Round Bar Specimen with a Surface Crack (표면균열을 갖는 원형봉재 시편을 이용한 고온 피로균열성장 연구)

  • So, Tae-Won;Yun, Gi-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.11
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    • pp.3415-3423
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    • 1996
  • The compact tension specimen geometry has been widely used for measuring fatigue crack growth rates at elevated temperature when the fatigue load is under tension/tension condition. However, most of the elevated temperature components which have significant crack growth life experience fatigue load under tension/compression conditions. Thus test techniques are required since the compact tension specimen cannot be used for tension/compression loading. In this paper, a simplified test procedure for measureing fatigue crack growth rates is proposed, which employs a round bar specimen with a small surface crack. Fatigue crack growth rates under tension/ tension loading conditions at elevated temperature were measured according to the proposed procedure and compared with those previously measured by C/(T) specimens. Since both the measured crack growth rates were comparable, the fatigue crack growth rates under tension/ compression load can be reliably measured by the proposed procedure. For monitoring crack depth. DC electric potential method is employed and an optimal probe location and current input conditions were proposed.