• Title, Summary, Keyword: Expansion anchor

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Dynamic Resistance of Anchor using Blasting Test and Numerical analysis for Earthquake (발파실험과 내진해석을 통한 Anchor의 동적 저항성에 관한 연구)

  • Choi, Kyung-Jip;Cho, Kook-Hwan
    • Journal of the Korean Society for Railway
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    • v.20 no.4
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    • pp.500-511
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    • 2017
  • Recently, as earthquakes have occurred in Gyeongju, interest in the stability of structures against vibration from earthquakes has increased. In Korea, the capacity of load resistance is mainly considered in the design of anchors. However, the vibration resistance characteristics of anchors have not been fully elucidated. The traditional type of anchor, which is a frictional resistance anchor, is often reported to fail due to vibration in construction procedures, such as blasting. The expansion type of anchor, on the other hand, could have more resistance to vibration but its capability of demonstrating vibratory resistance has to be investigated. In order to verify the vibratory resistance characteristics of expansion anchors against blasting and earthquake vibration, field tests and numerical analyses for seismic wave were performed. Field blasting test results show that the expansion anchor has better capability against vibratory load than does the frictional type anchor. Numerical analysis to earthquake also show that the expansion type anchor provides more resistance than does the frictional type anchor.

Development of an ACL Anchor: Effects of the Design Parameters on the Performance of a New Anterior Cruciate Ligament Fixation Device

  • Kim, Jong-Dae;Oh, Chae-Youn;Kim, Cheol-Sang
    • Journal of Biomedical Engineering Research
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    • v.29 no.2
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    • pp.132-138
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    • 2008
  • We investigated the biomechanical properties of a newly designed self-expansion type anterior cruciate ligament (ACL) anchor. The ACL anchor consists of the ring section giving the elastic force, the wedge for maintaining in contact with the femur tunnel wall and the link suspending hamstring graft or artificial ligament. The main design parameters that determine the performance of this device were the expansion angle (${\theta}$) and the thickness ($t_R$). The Ti6Al4V anchors were heated after inserting in a jig for 1 hour at $800^{\circ}C$ in a protective argon gas atmosphere and allowed to cool to room temperature in the furnace. In order to investigate the influence of the expansion angle and the thickness of the ring on the biomechanical properties of the anchor, the maximum pull-out load, stiffness and slippage of the ACL anchor were measured using the pull-out tester, and statistical analyses were also executed. The present results showed that the design parameters gave a significant effect on the performance of the self- expansion type of anchor. The pull-out load of the ACL anchors significantly increased as the thickness of the ring section was increased, having a similar trend for both expansion angles. The ACL anchor showed about 2.5 times higher values of the pull-out load than that of the minimum load (500N)required for the "accelerated rehabilitation". The optimum ${\theta}$ and $t_R$ values of this ACL anchor were suggested to have sufficient resistance against the pull-out force, high stiffness and relatively low slippage after ACL reconstruction.

Expansion Ratio of Pulse Power Underreamed Anchor (펄스방전 그라운드 앵커의 확공 특성에 관한 연구)

  • Kim, Nak-Kyung;Ju, Yonh-Sun;Kim, Sung-Kyu;Seo, Hyo-Kyun;Kim, Sun-Ju
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1107-1112
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    • 2009
  • Ground anchor should not be used in soft clay, because anchor resistance can not be guaranteed. However, there is a way to increase the capacity of anchors. The pulse powered anchor is an underreamed anchor by using high voltage electrokinetic pulse energy. In this study, a series of field test were carried out in order to find expansion rate related in number of pulse charge. and Anchor pull-out tests were performed at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. Data were analyzed in order to define a relation between expansion rate and ultimate pullout load.

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Pullout capacity Evaluation of anchor and anchor system development to prevent release of anchors in expansion joint (신축이음장치의 앵커 인발성능 평가 및 나사 풀림 방지를 위한 앵커시스템 개발)

  • Ha, Sang-Su
    • Journal of the Korea Institute of Building Construction
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    • v.10 no.1
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    • pp.65-72
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    • 2010
  • The failure of expansion joints for bridges generally occurs in non-shrinkage mortar another problem is the release of anchors in expansion joints due to the impact and vibration that occurs when cars are driving over a bridge. In this study, to overcome the failure of expansion joints that is related to the failure of non-shrinkage mortar, an elastomeric mortar has been developed. The elastomeric mortar has a highly developed pull-out capacity compared with that of non-shrinkage mortar. Moreover, an anchor system that can be changed easily and prevent the fracture of expansion joints has been developed.

The Study of Pullout-Behavior Characteristics of The Ground Anchor Using Expanded Hole (확공을 이용한 지압형 앵커의 인발거동 특성 연구)

  • Min, Kyong-Nam;Jung, Chan-Mook;Jung, Dae-Ho
    • Proceedings of the KSR Conference
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    • pp.1502-1508
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    • 2011
  • Ground anchor expands the hollow wall of settled part and has the structure which resists the designed tensile load by the bearing pressure generated by the wedge of the anchor body pressing in the expanded part. Such ground anchor has been recognized for stability and economicality since 1960s in technologically advanced nations such as Japan and Europe, and in 1970s, the Japan Society of Soil Engineering has established and announced the anchor concept map. The ground anchor introduced in Korea, however, has the structural problem where the tensile strength is comes only from the ground frictional force due to expansion of the wedge body. In an interval where the ground strength is locally reduced due to fault, discontinuation or such, this is pointed out as a critical weakness where the anchor body of around 1.0m must resist the tensile load. Also, in the installation of concrete block, the concentrated stress of concrete block constructed on the uneven rock surface causes damage, and many such issues in the anchor head have been reported. Thus, in this study, by using the expanded bit for precise expansion of settled part, the ground anchor system was completed so that the bearing pressure of ground anchor can be expressed as much as possible, and the bearing plate was inserted into the ground to resolve the existing issues of concrete block. Through numerical analysis and pullout test executed for verification of site applicability, the pullout-behavior characteristics of anchor was analyzed.

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Evaluation of Concrete Cone Breakout Strength of Expansion Anchors (익스팬션 앵커의 콘크리트 콘 파괴강도 평가)

  • Kim, Sung Yong;Kim, Kyu Suk
    • Journal of Korean Society of Steel Construction
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    • v.15 no.6
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    • pp.649-660
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    • 2003
  • The paper presents an evaluation of the tensile strength of the expansion anchor that can cause failure in the concrete based on the design of the anchorage. Tests of the heavy-duty anchor and the wedge anchor that are domestically manufactured and installed in plain concrete members are conducted to probe the effects of the embedded depth, concrete strength, and anchors spacing. The design of post-installed steel anchors is presented using the Concrete Capacity Design (CCD) approach. The CCD method is applied to predict the concrete failure load of the expansion anchor in plain concrete under monotonic loading for important applications. The concrete tension capacity of the fastenings with heavy-duty anchors and wedge anchors in plain concrete predicted using the CCD method is compared with the test results. For the CCD method, a normalization coefficient of 9.94 is appropriale for the nominal concrete breakout strength of an anchor or a group of wedge anchors in tension. On the other hand, a normalization coefficient of 11.50 is appropriate for the nominal concrete breakout strength of an anchor or a group of heavy-duty anchors in tension.

Expansion Ratio and Ultimate Load of Pulse-Discharge Bulbed Anchors (펄스방전 그라운드 앵커의 확공특성 및 극한인발력에 관한 연구)

  • Kim, Nak-Kyung;Kim, Sung-Kyu;Joo, Yong-Sun;Seo, Hyo-Kyun;Kim, Sun-Ju
    • Journal of the Korean Geotechnical Society
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    • v.25 no.7
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    • pp.5-10
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    • 2009
  • The ground anchor is not usually used in soft clay and loose sand, because the pullout resistance of anchors can not be guaranteed. However, there is a method to increase the capacity of anchors using electric discharge geotechnical technologies, which are also known as pulse discharge and electric-spark technologies. The pulse-discharge anchor has a bulbed (or underreamed) bond length that is expanded by high voltage electrokinetic pulse energy. 24 anchors were installed in the weathered soil and sandy clay at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. In this study, in order to define a relation between expansion rate of the anchor diameter and ultimate load, anchor load tests were carried out in accordance with testing procedures by AASHTO (AASHTO 1990) and FHWA (Weatheb 1998). And then several anchors were exhumed to measure the diameter of the pulse discharge anchors.

Cyclic Load Testing of Concrete Expansion Anchors

  • Gary L. Barnes;Lee, Sang-Myung
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.404-404
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    • 1996
  • In order to ensure a concrete expansion anchor is suitable for a given application, the load resistance behavior of the anchor must be known. ASTM E488 provides a standard method of testing expansion anchors for static and dynamic loads. Due to the many types of anchors available commercially and the large variability of applications, the ASTM does not delineate all details or requirements necessary to comprehensively determine the dynamic load behavior of concrete expansion anchors. A test program is presented in this paper which was developed and implemented to determine the cyclic load behavior of wedge-type concrete expansion anchors. Test results are also presented along with a discussion of the behavior of anchors, and their suitability for use.

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Anchor system in order not to Unscrew of Expansion Joint for Bridge (신축이음장치에서 나사 풀림을 방지하기 위한 앵커시스템)

  • Ha, Sang-Su;Choi, Dong-Uk;Lee, Chin-Yong
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.793-796
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    • 2008
  • The failure of expansion joint for bridge is generally occurred on the non-shrinkage mortar and other problem is the release of anchors in expansion joint due to the impact and vibration during the driven car on the bridge. In this study, to overcome the failure of expansion joint by the failure of non-shrinkage, the elastomeric mortar is developed. The pull-out capacity developed elastomeric mortar compared with that of non-shrinkage mortar. Moreover the anchor system which can be change easily and prevent a fracture of expansion joint is developed.

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A Case Study of Applicability of Machines of Pulse Powered Underreamed Anchors (펄스방전 확공형 앵커용 시공 장비의 적용성 검토)

  • Kang, Kum-Sik;Kim, Jae-Hyung;Cho, Gyu-Yeon;Kim, Tae-Hoon;Kim, Sun-Ju
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1100-1106
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    • 2009
  • This study intends to develop a pulse discharge device to strengthen the pushing power by expanding the cavity of the anchor settlement to form a spheric root for the purpose of constructing the economical and stable anchor. and, a series of field test were carried out in order to check applicability of machines of pulse powered underreamed anchors. Through the experiments, the electrical characteristics of the pulse power equipment had been identified it and the dynamic pressure generated from the subsequent change had been measured. Here, the measured dynamic pressure is the cavity expansion pressure to impact on the ground around the anchor settlement. Since this pressure has effects of cavity expansion and bored surface hardening with dynamic hardening effects on the anchor settlement, it is expected that it will largely contribute the increase of pushing power with a strong frictional resistance.

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