• Title/Summary/Keyword: Shear key

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Study on the Shear Key-shaped Mold making Method utilizing 3D Printers (3D 프린터를 활용한 전단키 형상 몰드 제작 방법에 관한 연구)

  • Jang, Jong-Min;Jang, Hyeon-O;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.5-6
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    • 2016
  • Due to the construction of high-rise and long axis etc, UHPC(Ultra High Performance Concrete) has attracted attention as a material that will replace the existing concrete. In order to improve the structural performance of each member joints, after demolding the concrete, method for surface treatment of the contact surface or by modifying the mold to create a shear key will be applied. In this study, to improve the conventional shear key manufacturing process, utilizing a 3d printer to produce a shear key plate. 3D printers have advantage it is inexpensively manufactured as compared with other production methods. Therefore, this study utilizes a 3D printer, we propose the shear key-shaped mold and plate shear key production measures.

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Experimental and Analytical Evaluation of Seismic Performance of Shear-Resistance Key (전단저항키 실험 및 내진성능평가)

  • 박종철;강형택;박찬민
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.523-528
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    • 2000
  • In multi-span bridges, a shear key is often used to distribute the seismic force to the case, the shear key is sometimes required to be reinforced to withstand the seismic force. To improve the strength of shear key, the strength and failure mode of shear key have to be carefully estimated and the proper reinforcement scheme should be elaborated. The test results show that the strength of shear key is 2.5 times higher than the strength calculated by PCI design handbook. Also the strength of shear key is greatly improved by placing PT bars into shear key. In this study, the analytical method to evaluate the strength of sheat key and the reinforcement scheme are proposed.

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A Study on Shield Tunnel Assembling System Using a Cable and Island-Type Shear Key (강연선과 아일랜드타입 전단키를 이용한 쉴드터널 체결기술 연구)

  • Ma, Sang-Joon;Lee, Young-Sub;Kim, Dong-Min
    • Journal of the Korean Geotechnical Society
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    • v.31 no.3
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    • pp.17-25
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    • 2015
  • In this study, a new segment assembling method using cable tensible force and island-type shear key was developed to improve the problems of bolt assembling method of shield tunnel. The bolting system and island-type shear key system were compared to analyze the mechanical behavior that occurs in the segment. The study results obtained from structural investigation and numerical analysis technique showed that the shear strength of island-type shear key is higher than that of the bolt system. With the increase of the tensile strength, it is expected that the stability of the segment will be secured.

Shear Key Design of Concrete Track on Bridge (교량구간 콘크리트궤도의 전단키 설계)

  • Back, Hyo-Sun;Lee, Ho-Ryong;Bae, Sang-Hwan;Cho, Hyun-Cheol
    • Proceedings of the KSR Conference
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    • pp.3251-3255
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    • 2011
  • Being the concrete track laid on bridge, due to track-bridge temperature difference, traction and brake force, and nosing force, the horizontal force can be applied to the track slab. Therefore, shear key structures to resist this horizontal force should be installed. The shear key structures installed in the Kyeong-Bu high-speed line are consisted of four shear keys at every slab with the length of 6 to 8m. However, in the point of view of construction, it is more advantageous to curtail the numbers of shear keys, and thus, the numbers and spacing of the shear keys should be carefully determined. In this study, hence, the effects of slab length, the numbers and spacing of the shear keys on design of shear key and track slab are examined.

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Effect of Shear Key and U strip on Flexural Behavior of Reinforced Concrete Beams Strengthened by CFS(Carbon Fiber Sheet) (탄소섬유쉬트로 보강된 철근콘크리트 보의 휨거동에 전단키와 U 스터립이 미치는 영향)

  • Choi, Hong-Shik;Lee, Chin-Yong;Yi, Seong-Tae;Lee, Si-Woo;Heo, Gweon
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.88-91
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    • 2004
  • It is generally known that the bonding strength of RC(Reinforced Concrete) flexural members strengthened by fiber sheet composites are sufficient and the bonding failure does not occur until the sheet failed. However, many researchers have been reported that, before the failure of the sheet, the bonding failure happens even though the bonding length is sufficient. This study was carried out to evaluate the effectiveness of shear key and U strip on flexural behavior of reinforced concrete beam structures. The ply number of CFS(Carbon Fiber Sheet), location of shear key, and existence or not of U strip were selected as the main test variables. Test results show that the behavior of a beam of which shear key is located in the nearby. of support and U strip is not existent, and having CFS of 1 ply is mostly improved.

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An experimental study for shear loading capacity of segmental members depending on various types of shear connector (전단연결부 형상에 따른 분절부재의 전단내하력에 대한 실험적 연구)

  • Han, Man-Yup;Kang, Tae-Heon;Shin, Jae-Woo;Jin, Kyung-Suk;Kang, Sang-Hun
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.158-161
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    • 2006
  • The numerical analysis and the experiment was performed to investigate the influences of shear connector on shear resistance capability. The numerical analysis's results should that the H/B ratio of shear key is more effective than angle of shear key against shear strength and shear behavior, and it is more desirable to use a half of the H/B ratio of shear key. The specimen was made with same condition as AASHTO recommended. There model tests were performed under various form of shear key, number, arrangement reinforcement and condition using epoxy. As a result of the experiment, there is little difference(or there is no difference) between the case of using epoxy on shear connector and the unused case.

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An Experimental Study on the Joints in Ultra High Performance Precast Concrete Segmental Bridges (초고성능 프리캐스트 콘크리트 세그멘탈 교량 접합부에 대한 실험 연구)

  • Lee, Chang-Hong;Chin, Won-Jong;Choi, Eun-Suk;Kim, Young-Jin
    • Journal of the Korea Concrete Institute
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    • v.23 no.2
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    • pp.235-244
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    • 2011
  • Failures of segmental bridges have been attributed to the inadequate joint connection techniques, which led to corrosion of the post-tensioned tendons connecting the segmental joints. The principal objective of this study is to evaluate the performances of the in-situ cast joint and epoxy applied shear key joints as a function of shear and ultimate strengths. Furthermore, shear behavior and strength of shear key joints in ultra high performance precasted concrete segmental bridges are experimentally evaluated to understand its shear failure behavior. The test parameters of shear key shape and type, load-displacement relations, cracking behavior, concrete strength, and fracture modes are considered in the study. Also, several parameters which influence the mechanical behavior of the shear key joint are analyzed. Based on the study results, the optimal shear key shape and joint type are proposed for the joint design and analysis guidelines.

Effect of Shear Key and Edge Length of Near Surface-Mounted FRP Plate in Concrete (콘크리트에 표면매입 보강된 FRP판의 전단키 및 연단거리 효과)

  • Seo, Soo-Yeon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.1
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    • pp.41-47
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    • 2016
  • This paper presents a bond test to find the effect of shear key and edge length from the bonded FRP in near surface-mounted(NSM) retrofit using FRP plate. Main parameters in the test are the location and size of shear key and the edge length. For the test, 10 specimens were made by embedding FRP plate of $3.6mm{\times}16mm$ into $400mm{\times}200(300)mm{\times}400mm$ concrete block and fixing it by using epoxy. Tensile load was applied to the FRP of the specimens until failure and was recorded at each load increase. In addition, the bond slip and elongation of FRP were measured during the test. From the test, it was found that the further the shear key located from the loading, the higher strength we could get. The bond strength inversely depended on the size of shear key. Especially, when the size of shear key was to be lagger than certain size, the bond strength decreased to very low value; even less than that of the case without shear key. The bond strength somewhat increased corresponding to the increase of edge length from the bonded end of FRP to loading in spite of same bond length. The bond-slip between FRP and concrete governed overall deformation in the bond test of NSM FRP so that the effect of excessive slip is necessary to be considered in the design.

Effects of Base Shape of Cantilever Retaining Wall in Soil Foundation on the Sliding Behavior (토사지반에 설치된 역 T형 옹벽의 저판형상이 활동거동에 미치는 영향)

  • Yoo, Nam-Jae;Lee, Myung-Woog;Kim, Young-Gil;Lee, Jong-Ho
    • Journal of Industrial Technology
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    • v.19
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    • pp.135-145
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    • 1999
  • This thesis is to investigate the sliding behavior of cantilever retaining wall by using the commercially available program of FLAC to simulate its behavior numerically. Cantilever retaining walls with flat base, sloped base and base with shear key, uniform surcharges being applied on the surface of backfill, were investigated to figure out appropriate location of shear key beneath the base of wall and, thus, its applicability to field condition was assessed by comparing the analyzed results to each other. On the other hand, previously performed centrifuge model test results (Eum, 1996) were analyzed numerically with FLAC to compare test results with respect to characteristics of load-settlement of surcharges and load-lateral movement of wall. Based on the failure mechanism observed during centrifuge tests, limit equilibrium method of finding the ultimate load inducing the sliding failure of wall was used to compare with values of the ultimate load obtained from conventional method of limit equilibrium method. Therefore, appropriate location of shear key was determined to mobilize the maximum resistance against sliding failure of wall.

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An Experimental Study on Bending Behaviour of Steel Grid Composite Deck Joint (격자형 강합성 바닥판 이음부의 휨거동에 관한 실험적 연구)

  • Shin, Hyun Seop;Lee, Chin Hyung;Park, Ki Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.5
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    • pp.68-77
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    • 2012
  • The joint of existing steel grid composite deck is composed of lap splice of reinforcing bar with end hooks and field-placed concrete. In this study, bending tests of deck joint composed of concrete shear key and high tension bolts are carried out for the design variable, concrete shear key strengthened with steel plate or not, and test results are compared with flexural performance of the existing deck joint. Test results showed that the mechanical deck joint has about 30% ~ 60% more ultimate bending strength than the existing joint. According to analysis results of moment-curvature relationship, the initial bending stiffness of the existing deck joint is some higher than that of mechanical joint. But, after crack failure the structural performance of the existing deck joint is rapidly reduced. Furthermore, the deck joint with the strengthened shear key with steel plate has more bending moment capacity than the deck joint without strengthening. And strengthening of shear key has positive influence on the increase of bending stiffness.