• Title/Summary/Keyword: 프리캐스트

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Determination Method for Longitudinal Initial Prestress in Composite Beams with Precast Decks I: Simply Supported Beams (프리캐스트 바닥판을 사용한 강합성보의 교축방향 초기 프리스트레스 산정방법 I : 단순보)

  • Cho, Sun-Kyu;Lee, Jong-Min
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1A
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    • pp.15-24
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    • 2008
  • This paper presents the analytical method for the long-term behavior of simply supported composite beams with precast decks prestressed in the longitudinal direction. The objectives of time-dependent analysis are to estimate losses of prestress on the concrete slab and long-term deflection due to creep and shrinkage of concrete, relaxation of prestressing steel. Also, the time-dependent analysis was carried out using the presented analytical method to evaluate the effects of several parameters on the long-term behavior of composite bridge with precast deck, including geometrical shapes of composite beams, compressive strength of concrete and magnitude of initial prestress. The results of the analysis indicated that, in the effects of geometrical shapes of composite beams, the main parameters affecting the losses of prestress and the long-term deflection were the cross sectional area and the moment of inertia of steel beam, respectively. Finally, the determination method for the required initial prestress was proposed by evaluation of the loss characteristics due to shrinkage and creep of concrete.

Numerical study on the structural stability of the precast joint buttress wall (프리캐스트 조인트 방법을 사용한 부벽식 옹벽의 구조적 안정성에 대한 수치해석 연구)

  • Kim, Joonseok
    • Journal of the Society of Disaster Information
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    • v.12 no.4
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    • pp.366-372
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    • 2016
  • Recently in case of the concrete retaining wall precast technological change in the field assembled by the way. A precast wall is devied into upper and lower respectively, and the way, assembled in field is being performed. But the assembled part could have been damaged by the earth pressure in a relatively high buttress wall. And, it have been pointed out that large-scale disaster can be occurred. Thus, in this thesis, a structural stability for the buttressed retaining wall with pre-cast joint method was analyzed by a numerical analysis method. The structural stability of the three height retaining wall(7.6m, 8.5m, 10m) was conducted respectively for earth pressure. The maximum principal stress applied to the concrete retaining wall was analyzed to occur locally in the vicinity of the fixing anchor as 23.3 ~ 43.2 MPa.

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.

Evaluation on Flexural Performance of Precast Bridge Decks with Ribbed Connection (요철형 이음단면을 갖는 프리캐스트 교량 바닥판의 휨성능 평가)

  • Shin, Dong-Ho;Park, Se-Jin;Oh, Hyun-Chul;Kim, In-Gyu;Kim, Young-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.3
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    • pp.1-9
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    • 2015
  • Due to the increasing number of deteriorated bridges worldwide, the importance of maintenance and replacement of existing bridges are being emphasized. Cast-in-place concrete deck which is mainly applied to deck replacement of existing bridges have problems such as deterioration concerns by initial crack, labor cost increase, difficulties of maintenance and replacement, construction time increase, and indirect cost increase by traffic congestion. On the contrary, a precast concrete deck is considered as an effective alternative because of its quality assurance and accelerated construction. The connection method ensuring the required strength and durability is especially important, because the connection part of the precast concrete deck is vulnerable to cracks and leakage. Therefore, this study proposes precast bridge decks with ribbed connection which are more improved than existing bridge deck joints, and flexural performance is verified through various parameter tests.

Reversed Cyclic Loading Tests on Precast Beam-Column Joints with Headed Reinforcement (프리캐스트 보-기둥 헤드철근 연결부 반복하중 실험)

  • Kim, In-Gyu;Yu, Sung-Yong
    • Journal of the Korea Concrete Institute
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    • v.15 no.3
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    • pp.369-376
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    • 2003
  • One of the most complex reinforcement location in the precast building frame is the beam-column joint in a prefabricated construction. It is generally resulted from the vortical bars of column, anchorage bars of beam, and bars of hoop. Particularly the hooked anchorage bars of beam are confronted with hoop and main column bars. The headed reinforcement is considered to place them easily and to reduce the anchorage length in a precast construction. Reversed cyclic loading tests are performed on four beam-column specimens to evaluate the strength and behavior of beam to column and column to column connections. The result of test shows that the headed reinforcement has a similar performance than that of hooked reinforcement in a precast specimen with strong column and weak beam joints. The splice column joints which are used frequently in the domestic fields also show reliable behaviors in those tests with strong column and weak beam joints.

Deformation and Stress Distribution of Discontinuous Precast Concrete Track Slab : II. Stress Distribution (불연속 프리캐스트 콘크리트궤도 슬래브의 변형과 응력 분포 : II. 응력 분포)

  • Lee, Dong Hoon;Kim, Ki Hyun;Jang, Seung Yup;Zi, Goangseup
    • Journal of the Korean Society for Railway
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    • v.20 no.5
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    • pp.637-648
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    • 2017
  • In this paper, the effects of initial built-in deformation and temperature deformation on the stress distribution of discontinuous precast concrete track slab under train load were examined. According to the results, when train load is put on a precast concrete slab with initial built-in deformation and deformation due to temperature gradient, the maximum tensile stresses develop at the upper side of slab in the slab center, edge center and corner of shear pocket; the stress distribution is different from that of the case under train load only. Therefore, to accurately predict the actual weak points and failure modes, one should calculate the stress under train load considering the initial built-in and temperature deformation of the slab.

Structural Performance Evaluation on Ended Block of Wide Flange PSC Girder for the Semi-Integral Bridges (광폭 플랜지 PSC 거더 단부 프리캐스트 블록을 활용한 반일체식교대교량의 구조성능 평가)

  • Ka, Hoon;Choi, Jin-Woo;Kim, Young-Ho;Park, Jong-Myen
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.42 no.1
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    • pp.1-9
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    • 2022
  • Semi-integral abutment bridges are a type of integral abutment bridges. These bridges eliminate expansion joints on the structure and can be used in situations not suitable for full-integral abutment bridge. Moreover, Semi-integral bridges have excellent maintenance and can be economically constructed. This study is about precast wall-type blocks at each end which provide lateral support for PSC girder, as well as acting as retaining walls to resist longitudinal movement of semi-integral abutment bridge. The end-diaphragm connection between ended blocks of PSC girders can be achieved by in-suit nonshrinkage concrete. The results show that 3-point experiment of end-diaphragm beam have an acceptable performance which is so better than results of structural design. Moreover, the effects of backfill soil on semi-integral abutment bridge constructed are analyzed the behavior according to the temperature changes.

Study on the Performance of New Shear Resistance Connecting Structure of Precast Member (프리캐스트 부재의 새로운 전단저항 연결체의 성능에 관한 연구)

  • Kim, Tae-Hoon;Jin, Byeong-Moo;Kim, Young-Jin;Kim, Seong-Woon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1A
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    • pp.147-154
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    • 2008
  • The purpose of this study is to critically evaluate the structural performance of an innovative new shear resistance connecting structure of precast member. Joints such as shear resistance connecting structure require special attention when designing and constructing precast segmental structures. An experimental and analytical study was conducted to quantify performance measures and examine one aspect of detailing for developed shear resistance connecting structure. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. A joint element is used to predict the inelastic behavior of the joints between segmental members. Future work by the authors will do a model test of precast segmental prestressed concrete bridge columns with this shear resistance connecting structure, and examined both the structural behavior and seismic performance.

Behavior of PSC Composite Bridge with Precast Decks (프리캐스트 바닥판 PSC 합성거더 교량의 거동)

  • Chung, Chul Hun;Hyun, Byung Hak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5A
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    • pp.873-880
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    • 2006
  • PSC composite bridge with precast decks which was designed by the proposed horizontal shear equation was fabricated. Fatigue test was performed to evaluate the endurance of shear connection and the behavior of PSC composite bridge. After all the fatigue loading were applied, no crack and no residual slip were occurred. The flexural stiffness of PSC composite bridge was maintained the initial value, and demage of shear connection was not occurred. To verify the applicability of horizontal shear equation and shear connection detail and to evaluate the strength of PSC composite bridges, static test was also executed. PSC composite bridges with precast decks had 2.08 safety factor which was the ratio of crack to serviceability load and showed ductile behavior after ultimate load. Test results showed that the proposed design equation of the shear connection gave reasonable horizontal shear connection design. Fast and easy construction would be achieved using the suggested precast system.

An Analytical Study for Structural Behaviors of Unbonded Precast Rectangular Hollow Section Concrete Piers (비부착 프리캐스트 중공 사각 단면 교각의 구조거동에 관한 해석적 연구)

  • Choi, Seung-Won;Kim, Ick-Hyun;Cho, Jae-Yeo;Chang, Sung-Pil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.1A
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    • pp.61-69
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    • 2010
  • Unbonded precast concrete piers have better seismic performances than conventional reinforced concrete piers. In this research, seismic performances of unbonded precast prestressed concrete piers are analyzed using OpenSEES. Main parameters of analysis are concrete strength, jacking force ratio, ratio of tendon, and size of precast segment. In results, as the ratio of tendon and jacking force ratio increase, the flexural strength increases at softening state and ultimate state. Concrete strength and size of precast segment are negligible. But initial jacking force ratio leads to early yielding of prestressing tendon. Since compressive strain in core concrete is much less than ultimate strain, it can be expected that the amount of transverse steel reinforcement is to be reduced in comparison with conventional reinforced concrete column.