• Title/Summary/Keyword: 전단키

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Performance Evaluation of Waveform Micropile with Different Shapes by Centrifuge Test (원심모형실험을 이용한 파형 마이크로파일 형상에 따른 성능평가)

  • Jang, Young-Eun;Han, Jin-Tae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.6
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    • pp.1049-1057
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    • 2016
  • The waveform micropile is a type of foundation that has a single or multiple shear keys on the pile shaft, and it is constructed through a jet grouting method as a way to increase the shaft resistance of the bonded area between the pile and the soil. In this paper, a geotechnical centrifuge test was performed to study the axial performance of the waveform micropile from other models. The six test models consisted of three waveform micropiles with a single shear key at three different depths, a waveform micropile with multiple shear keys, a conventional micropile, and a jet grouting micropile. Based on the test results, it was clearly shown that the waveform micropile increased in its bearing capacity compared to the other models without the shear key. Additionally, it was observed that the confining pressure for the location of a shear key is directly related to the increase of the bearing capacity.

Dynamic Analysis for Base Isolated Structure with Shear Keys (쉬어키를 가진 면진건축물의 동적해석)

  • Han, Duck-Jeon;Kim, Tae-Ho
    • Journal of Korean Association for Spatial Structures
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    • v.7 no.1
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    • pp.45-53
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    • 2007
  • Recently, high-rise base isolated building structures with shear keys are often constructed in Japan which frequently occurs earthquakes. High-rise buildings are less damaged because those buildings have longer natural period than md or low rise buildings. The shear key is device that prevents the base isolators operating by the wind loads not by the earthquake loads. In case of big base shear force acts on the shear keys by earthquake, this device is broken and base isolator is operated. Therefore, seismic intensities play a role in acting on the shear keys. If wind loads are hither than the earthquake loads, the shear keys designed by wind loads are not operated in earthquakes. So, the requirements of shear keys in high-rise base isolated building structures must be examined in Korea with moderate seismic legions. In this study shear keys are applied with 5 and 15 stories base isolated building structures and investigated their dynamic responses to original and 1/2 scale downed El Centre NS(1940) ground motions. The results show that the yield shear forces of the shear keys affect significantly the dynamic behavior of base isolated building structures

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Strength Estimation of Joints in Floating Concrete Structures Subjected to Shear (전단을 받는 부유식 콘크리트 구조물 접합부의 강도 평가)

  • Yang, In-Hwan;Kim, Kyung-Cheol
    • Journal of Navigation and Port Research
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    • v.37 no.2
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    • pp.155-163
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    • 2013
  • This study explores the structural behavior of module joints in floating concrete structures subjected to shear. Crack patterns, shear behavior and shear capacity of shear keys in joints of concrete module were investigated. Test parameters included shear key shape, or inclination of shear keys, confining stress levels and compressive strength of concrete. Test results showed that shear strength of joints increased as shear key inclination increased. Test results also showed that shear strength of concrete module joints increased with the increase of confining stress levels. The equation for predicting shear strength of joints was suggested, which was based on the test results. Shear strength prediction by using the equation suggested in this study showed good agreement with test results.

Analysis of Shear Behavior of Shear Key for Concrete Track on Railway Bridge Considering Construction Joint (타설 경계면을 고려한 철도교 콘크리트궤도 전단키의 전단 거동 해석)

  • Lee, Seong-Cheol;Kang, Yun-Suk;Jang, Seung Yup
    • Journal of the Korean Society for Railway
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    • v.19 no.3
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    • pp.341-350
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    • 2016
  • Concrete track on railway bridges should be designed to effectively respond to the movement of the superstructure of the bridge. In the design procedure, shear keys are generally placed on the protection concrete layer (PCL) before casting the concrete track so the shear force due to slip between the concrete track and the bridge super-structure can be transferred. In this paper, a nonlinear structural analysis procedure that considers the construction joint has been developed to predict the shear behavior of a shear key. With the developed analysis procedure, it was possible to predict the shear force-shear slip response at the construction joint in a shear key by considering the friction of concrete surface and the dowel action of the rebars. The analysis results showed good agreement with the test results for 4 specimens.

An Experimental Study on the Evaluation of Bearing Strength of the Vertical Joint in Precast Concrete Large Panel Structures (대형판 조립식 구조 수직접합부 지압강도 평가에 관한 연구)

  • Chung, Lan;Cho, Seung-Ho;Hwang, Min-Ha
    • Magazine of the Korea Concrete Institute
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    • v.8 no.4
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    • pp.181-189
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    • 1996
  • It is well-known that the hearing strength in vertical joints of precast concrete large panel system is affected by grout compressive strength angle of shear key and bearing area. 21 vertical joint specimens were tested to investigate the effects of these parameters The analysis of test results shows that : 1. The higher be grout compressive strength, the higher will shear strength be. And the bearing strength does not so increase in proportion of bearing area. 2. The shear key with the angle of $20^{\circ}$shows the highest bearing strength among three angle variables of $20^{\circ}$, $25^{\circ}$, $30^{\circ}$.

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.

Strength of Joint in Floating Structures Constructed with Precast Concrete Modules (프리캐스트 콘크리트 부유식 구조물의 모듈 접합부 강도)

  • Yang, In-Hwan;Kim, Kyung-Cheol
    • Journal of Navigation and Port Research
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    • v.36 no.3
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    • pp.197-204
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    • 2012
  • The behavior of floating structures constructed with precast concrete modules is dependent of the behavior of joints between the concrete modules. To accurately predict the floating structure response under the ultimate loading, knowledge of joint behavior is essential. This study aims to investigate the structural behavior of concrete module joints under various configuration of joint and confining stress levels. The shear behavior, shear capacity and crack patterns of shear keys in concrete module have been studied. Test results indicated that the shear capacity of joints increased as shear key inclination increased. In addition, shear capacity of concrete module joint increased with the increase of confining stress levels. The test results were compared with the AASHTO design recommendations. The AASHTO design recommendations underestimated the shear strength of test specimens.

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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An Approach on the Prediction of Load-Carrying Capacity of Reinforced-Precast Concrete Joint with Shear Keys (프릴캐스트 콘크리트 전단키 접합부의 극한강도 예측방법)

  • 윤재진;남정수
    • Magazine of the Korea Concrete Institute
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    • v.4 no.4
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    • pp.135-147
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    • 1992
  • 본 연구는 기존의 이론을 배경으로 전단키에 영향을 미치는 전달전달의 요소가 포함된 기본식을 산정하여, 접합부의 유형에 따라 구체적으로 전단강도를 예측하는 방법을 제안하였다. 접합부 콘크리트와 횡보강철근의 강도 및 장부호과를 고려한 프리캐스트 콘크리트 전단키 접합부의 기본극한강도식은 수정 Mohor-Coulomb의 파괴기준과 항복선의 도입에 의하여 전개하였고, 극한전단능력의 근사해는 상하계법에 의한 극치해석의 수법을 이용하여 구하고 여기에 재료의 유효강도계수를 도입하였다. 또한, 지존의 실험결과와 비교하여 그 적용성을 고찰하였다.

Study on Affecting Factors for the Segmental Joint Behavior of Spliced Girder Bridges (분절교량 접합부 거동의 영향인자에 대한 연구)

  • Nam, Jin-Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.3
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    • pp.9-16
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    • 2019
  • Recently, precast PSC girder bridges have been widely applied for short and middle span bridges. The construction of the spliced girder bridges has been increasing to overcome the length limit of girder and transportation restrictions. In case of the spliced girder, the integrity of the segmental joints is very important to secure the structural soundness of bridge because the discontinuity on the segmental joints between adjacent segments could be vulnerable point. The study of segmental joint behavior with different influence factors of joint type, shear key installation, confining force is very important. In this research, finite element analysis and scaled model test with different shear key shapes and confining forces were carried out and the comparative study was performed to evaluate the segmental joint behavior of precast spliced PSC girder bridge. It was confirmed that the installation of shear key with height and depth ratio of 1/2~1/3 and applying of confining force of 1/2 of the concrete strength at the joint was effective in improving the integrity of segmental joint. In addition, the field loading test for existed precast spliced PSC girder bridge was performed and the measurement of the difference of deflection between adjacent segments at segmental joint was proposed as the assessment solution of the integrity of segmental joint.