• Title, Summary, Keyword: Slab joint

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Numerical study of stress states near construction joint in two-plate-girder bridge with cast-in-place PC slab

  • Yamaguchi, Eiki;Fukushi, Fumio;Hirayama, Naoki;Kubo, Takemi;Kubo, Yoshinobu
    • Structural Engineering and Mechanics
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    • v.19 no.2
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    • pp.173-184
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    • 2005
  • For reducing construction cost, two-plate-girder bridges are getting popular in Japan. This type of bridge employs a PC slab, which is often cast-in-place. In such a case, concrete is not usually cast over the whole slab at one time: some portions are constructed earlier than the rest. Therefore, a construction joint is inevitably created. Due to the drying shrinkage of concrete, tension stress may occur in concrete slab. High tensile stress can be expected near the construction joint where concretes with different ages meet. Moreover, prestressing is not applied over the whole length of slab at one time. This may also serve as a source of tensile stress in the slab. Thus there is a chance that cast-in-place PC slab, especially near the construction joint, may be subjected to tensile cracking. In the present study, stress states near the construction joint in the cast-in-place PC slab of a two-plate-girder bridge are investigated numerically. The finite element method is employed and the three-dimensional analysis is conducted to see the influence of dry shrinkage and prestressing. The stress states in the PC slab thus obtained are discussed. The simplified model of a plate girder for this class of analysis is also proposed.

Analysis of Slab Joint Opening Due to Temperature Drop in Continuous Precast Concrete Slab Track (연속 프리캐스트 콘크리트 슬래브궤도에서의 온도하강에 따른 슬래브 이음매 개구량 해석)

  • Jang, Seung-Yup;Lee, Jeong-Wan
    • Proceedings of the KSR Conference
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    • pp.1659-1663
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    • 2011
  • Precast concrete slab track is a track structure to be installed by transporting and assembling precast concrete slabs manufactured at the factory. This method can improve concrete quality, provide easy maintenance and reduce construction time, compared with in-situ concrete track. However, the concrete slabs being continuously connected in longitudinal direction, due to the temperature change between summer and winter, the openings at slab joints have occurred. Thus, in this study, to identify the cause of this opening of slab joint, the joint opening caused by temperature drop in the longitudinally continuous precast concrete slab track has been predicted using three-dimensional finite element analysis, and compared with field measurements. Based on the proven model, the slab joint opening, and the stress pattern of concrete slab and steel reinforcement according to concrete slab-base friction properties, concrete-reinforcement bond properties, and prestressing were analyzed.

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Analysis of the Fundamental Behaviors of the Middle Slab in a Double-Deck Tunnel for Design Guide Development (복층터널 중간슬래브 설계 기준 마련을 위한 기본 거동 특성 분석)

  • Park, Hee Beom;Cho, Young Kyo;Lee, Young Hoon;Kim, Seong-Min
    • International Journal of Highway Engineering
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    • v.19 no.1
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    • pp.63-72
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    • 2017
  • PURPOSES : The purpose of this study is to investigate the fundamental behaviors such as stresses and deflections of the middle slab in a double-deck tunnel for the development of a middle slab design guide. METHODS : The middle slab has been divided into the following three different sections as according to its structural differences: the normal section, expansion joint section, and emergency passageway section. The normal section of middle slab represents the slab supported by brackets installed continuously along the longitudinal direction of tunnel lining. The expansion joint section refers to a discontinuity of middle slab due to the existence of a transverse expansion joint. The emergency passageway section has an empty rectangular space in the middle slab that acts as an exit in an emergency. The finite element analysis models of these three sections of middle slab have been developed to analyze their respective behaviors. RESULTS : The stresses and deflections of middle slab at the three different sections decrease as the slab thickness increases. The emergency passageway section yields the largest stresses and deflections, with the normal section yielding the smallest. CONCLUSIONS : The stress concentrations at the corners of the passageway rectangular space can be reduced by creating hunch areas at the corners. The stresses and deflections in the emergency passageway section can be significantly decreased by attaching beams under the middle slab in the passageway area.

Ductility of Column-Slab eoint in R/C Flat Plate System (플랫 플레이트 구조의 기둥.슬래브 접합부 연성에 관한 연구)

  • 김형기;박복만
    • Journal of the Korea Concrete Institute
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    • v.12 no.4
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    • pp.113-119
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    • 2000
  • The R/C flat plate system provides architectural flexibility, clear space, reduced building height, simple formwork, which consequently enhance constructibility. One of the serious problems in the flat plate system is brittle punching shear failure due to transfer of shear force and unbalanced moments in column-slab joint. Recently, the flat plate system accompanied with shear walls to resist the lateral loads is applied to high-rise buidings. Although the flat plate system is not considered in design as part of the lateral load-resisting system, it is required that this system keeps the ductile behavior for the lateral displacement of the building. However, it is unclear whether the column-slab joint possesses ductility enough to survive the lateral deformation. The objective of this paper is to investigate the major parameters that influence the ductility of R/C flat plate system by examining the existing experiments on column-slab joint. The effects of gravity load and shear reinforcement on the ductility of the flat plate system are presented.

An Experimental Study on Structural Behavior of Half Slab Reinforced by Truss Mesh (트러서메쉬 보강 하프 슬래브의 구조적 거동에 관한 실험적 연구)

  • Ko, Man-Young;Kim, Yong-Boo;Park, Hyun-Soo;Chung, Lan
    • Magazine of the Korea Concrete Institute
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    • v.7 no.4
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    • pp.119-128
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    • 1995
  • This paper summarizes experimental results for studying feasibility and structural behavior of' a half slab which is getting popularity in recent building construction in favour of the savings in manpower, coats, and construction period. 17 specimens were tested to investigate and analyze the flexural strength of precast concrete slab, half slab, and half slab-wall joint. The primary variables of the testing program were: thickness of precast concrete slab, truss mesh shape, and type of loadings. Test results show that the flexural strength of precast concrete slab in reverse loading is lower than the design strength, but the flexural strength of precast concrete slab, half slab and half slab-wall joint in direct loading is higher than the design srength. No horizontal cracks were found in the connection between insitu concrete and precast concrete slab. The flexural strength of half slab and half slab-wall joint was the same as that of reinforced concrete members. This study concludes that there will not be any structural problem in using a half slab reinforced by truss mesh if props spacing of 2.0m-2.5m, cleanness, and rough finishing between precast concrete and insitu concrete slab are kept.

Investigation of Load Transfer Characteristics at Slab Joints In The Floating Slab Track by Equivalent Shear Spring Model (등가 전단 스프링 모델을 이용한 플로팅 슬래브궤도 연결부에서의 하중전달 특성 분석)

  • Jang, Seung-Yup;Ahn, Mi-Kyoung;Choi, Won-Il;Park, Man-Ho
    • Proceedings of the KSR Conference
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    • pp.2838-2843
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    • 2011
  • Recently, the floating slab track that can effectively mitigate the vibration and structure-borne noise is being discussed to be adopted. The floating slab track which is a track system isolated from the sub-structure by vibration isolators. Unsimilarly to conventional track and the slab deflection is large. Therefore, the running safety and ride comfort should be investigated. Especially at slab joint since the load cannot be transferred, the possibility that the dynamic behavior of track and train became unstable is high. Thus, in general dowel bar are often installed at slab joints. To determine the appropriate dowel ratio the load transfer characteristics should be investigated. In this study, dowel bar joint is modeled by equivalent shear spring and this model is verified by comparison with experimental results. Using the proven model, the load transfer efficiency and deflection at slab joint according to dowel ratio, and stiffness and spacing of vibration isolator were examined.

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Transverse Concinement and Slab Effect on Shear Behavior of Beam-Column Connection (보-기둥 접합부의 전단거동에 대한 슬래브 및 횡구속 영향)

  • 장극관;서대원;방세용
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.419-422
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    • 1999
  • This study was intended to investigate the cyclic behavior of high strength concrete beam-column connection. Four assemblies were designed 2/3 scale beam-column-slab joint and tested. The obtained results are follows. 1) The transverse beams increase the shear resistance and ductility of joint, 2) The slab was contributed to increase of the flexural capacity of the beam, but was not contributed to increase the joint ductility under lateral loads.

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Structural Performance of Seismic Resistance Capacity of Carbon Sheet-Angle Retrofitting Method in Wall-Slab Joint (탄소섬유와 L형강을 이용한 벽-슬래브 접합부의 보강성능)

  • Roh Gong-Ki;Park Tae-Won;Park Hyun-Soo;Chung Lan
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.65-68
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    • 2004
  • In the seismical capacity evaluation for RC structure wall-slab joint is very important factor. Because lateral load is resistance element and gravity load resistance element are acted mutually in the wall-slab joint. In this paper, to improve the seismic capacity of the wall-slab joint in the existing wall type apartments experiment which improve and retrofit a seismic capacity by unequal angle bracing and carbon sheet attachment are carried out. These methods are also economic and simple in mitigating seismic hazard, improve earthquake-resistance performance, and reduce risk level of building occupants. From the experimental results, the change of strength, degration of stiffness, and energy dissipation are evaluated. It can be concluded that these methods are effective in improving the seismic performance.

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Characteristics of Middle Slab Stresses in Double-Deck Tunnel During Maintenance (복층터널 중간슬래브 유지관리에 따른 응력분포 특성 분석)

  • Cho, Young Kyo;Lee, Young Hoon;Park, Beom Keun;Kim, Seong-Min
    • International Journal of Highway Engineering
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    • v.19 no.6
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    • pp.47-56
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    • 2017
  • PURPOSES : The purpose of this study is to investigate the stresses of the middle slab in a double-deck tunnel owing to the slab lift to replace the underlying elastic pads during maintenance work. METHODS : The middle slab was divided into three different sections: typical section, expansion joint section, and emergency passageway section. Finite element analysis models of these three sections of middle slab were developed, and the stress distribution and maximum stresses were obtained using the models when the middle slab was lifted to replace the underlying elastic pads. Various slab lifting methods were examined in this study such as one-, two-, and multiple-point lifts, distributed lifts, and one or both slab side edge lifts. RESULTS : When the slab side edge is lifted, the longitudinal stresses of the slab are almost the same as the principal stresses. This implies that the governing stresses are the longitudinal stresses. The maximum stresses with both-edge lifts are generally smaller than those with one-edge lifts at all three sections of middle slab. CONCLUSIONS : If the middle slab in a double-deck tunnel is lifted for maintenance, the slab should be lifted at multiple points along the longitudinal direction to reduce the tensile stresses.

Study on the Shape of a Longitudinal Joint of the Slab-type Precast Modular Bridges (슬래브 형식 프리캐스트 모듈러교량의 종방향 연결부 형상 결정에 관한 연구)

  • Lee, Sang Yoon;Song, Jae Joon;Kim, Hyeong Yeol;Lee, Young Ho;Lee, Jung Mi
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.5
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    • pp.98-111
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    • 2012
  • In this study, a longitudinal joint connection was proposed for the short-span slab-type precast modular bridges with rapid construction. The slab-type modular bridge consists of a number of precast slab modules and has the joint connection between the modules in the longitudinal direction of the bridge. The finite element based parameter analysis and the push-out test were conducted to design the shape and the dimensions of the longitudinal joint connection. Number of shear keys within the joint, height and depth of the shear key, tooth angle, and the spacing were considered as the design parameters. Using the local cracking load obtained from the analytical and experimental results, an efficiency factor was proposed to evaluate the effectiveness of the longitudinal joint connection. The dimensions of shear key were determined by comparing the efficiency factors.