• Title, Summary, Keyword: Precast

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Crack width control of precast deck loop joints for continuous steel-concrete composite girder bridges

  • Shim, Changsu;Lee, Chidong
    • Advances in concrete construction
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    • v.10 no.1
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    • pp.21-34
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    • 2020
  • Precast deck joints have larger crack width than cast-in-place concrete decks. The initial crack typically occurs at the maximum moment but cracks on precast joints are significant and lead to failure of the deck. The present crack equation is applied to cast-in-place decks, and requires correction to calculate the crack width of precast deck joints. This research aims to study the crack width correction equation of precast decks by performing static tests using high strength and normal strength concrete. Based on experimental results, the bending strength of the structural connections of the current precast deck is satisfied. However it is not suitable to calculate and control the crack width of precast loop connections using the current design equation. A crack width calculation equation is proposed for crack control of precast deck loop joints. Also included in this paper are recommendations to improve the crack control of loop connections.

Precast Concrete Copings for Precast Segmental PSC Bridge Columns : I. Development and Verification of System (프리캐스트 세그먼트 PSC 교각의 조립식 코핑부 : I. 시스템 개발 및 검증)

  • Kim, Tae-Hoon;Park, Se-Jin;Kim, Young-Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.5A
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    • pp.463-473
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    • 2010
  • The purpose of this study was to investigate the performance of precast concrete copings for precast segmental PSC bridge columns. The proposed system can reduce work at a construction site and makes construction periods shorter. The precast concrete copings provides an alternative to current cast-in-place systems, particularly for areas where reduced construction time is desired. A model of precast concrete copings was tested under quasistatic monotonic loading. As a result, proposed precast coping system was equal to existing cast-in-place system in terms of required performance. In the companion paper, the experimental and analytical study for the performance assessment of precast concrete copings for precast segmental PSC bridge columns is performed.

Quasi-static test of the precast-concrete pile foundation for railway bridge construction

  • Zhang, Xiyin;Chen, Xingchong;Wang, Yi;Ding, Mingbo;Lu, Jinhua;Ma, Huajun
    • Advances in concrete construction
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    • v.10 no.1
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    • pp.49-59
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    • 2020
  • Precast concrete elements in accelerated bridge construction (ABC) extends from superstructure to substructure, precast pile foundation has proven a benefit for regions with fragile ecological environment and adverse geological condition. There is still a lack of knowledge of the seismic behavior and performance of the precast pile foundation. In this study, a 1/8 scaled model of precast pile foundation with elevated cap is fabricated for quasi-static test. The failure mechanism and responses of the precast pile-soil interaction system are analyzed. It is shown that damage occurs primarily in precast pile-soil interaction system and the bridge pier keeps elastic state because of its relatively large cross-section designed for railways. The vulnerable part of the precast pile with elevated cap is located at the embedded section, but no plastic hinge forms along the pile depth under cyclic loading. Hysteretic curves show no significant strength degradation but obvious stiffness degradation throughout the loading process. The energy dissipation capacity of the precast pile-soil interaction system is discussed by using index of the equivalent viscous damping ratio. It can be found that the energy dissipation capacity decreases with the increase of loading displacement due to the unyielding pile reinforcements and potential pile uplift. It is expected to promote the use of precast pile foundation in accelerated bridge construction (ABC) of railways designed in seismic regions.

Evaluation of Stiffness Structure and Grouting Efficiency beneath the Precast Slab Track by Elastic Wave Tests (탄성파시험에 의한 프리캐스트 슬래브궤도의 강성구조와 충전성능 평가)

  • Lee, Il-Wha;Joh, Sung-Ho;Jang, Seung-Yup;Kang, Youn-Suk;Han, Sung-Woo
    • Proceedings of the KSR Conference
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    • pp.1303-1308
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    • 2007
  • Recently, precast concrete tracks are replacing ballast track for efficient and economic maintenance of track. Precast concrete railroad tracks are manufactured in factory, and transported to railroad construction site for installation. Therefore, quality of precast concrete track itself should be sufficiently good. On the contrary to the convenient manufacturing of precast concrete track, the installation of a precast concrete track requires careful steps. Typically, a precast concrete track is placed on an approximately 15-cm thick lean concrete layer. A mortar is filled between lean concrete layer and precast concrete track to adjust the sloping angle of a precast concrete track for a safe train operation at a curvy section. Then, the use of filled mortarproduces a void underneath a precast concrete track, which is harmful to structural safety of a precast concrete track undercyclic loading. Therefore, it is essential to make sure that there is no void left beneath a precast concrete track after mortar filling. In the continuous resonance method, the amplitude of frequency response measured using an instrumented hammer and an accelerometer is plotted against a pseudo-depth, which is half of the wave velocity divided by frequency. The frequency response functions are measured at consecutive measurement locations, 6-cm interval between measurement points, and then combined together to generate a 2-D plot of frequency response. The sections with strong reflections or large amplitude of frequency response are suspicious areas with internal voids and unfilled areas. The 2-D frequency response plot was efficient in locating problematic sections just by examining the color shade of a visualized plot in 2-D format. Some of the problematic sections were drilled to make a visual inspection of mortar filling. The visual image of interface between mortar and precast concrete track was verified using the validity of the continuous resonance technique adopted in this research.

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Development Trends of Precast Polymer Concrete Products (프리캐스트 폴리머 콘크리트의 개발동향)

  • 연규석;이봉학;김광우;김태경;김관호
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.99-104
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    • 1992
  • There is a limit manufacturing precast products for the construction industry using conventional cement concrete and precast iron due to many reasons. Therefore, precast product technologies using polymer concrete are widely developed across the world because using polymer concrete can be over come this limitation. This study reviewed and analyzed the trends of development and practical usages of ploymer concrete precast products in foreign countries based on selected literatures. It was observed that polymer concrete precast products have been widely used as utility structures wall and slab members. decoration products, traffic products, hydraulic structures and industry equipments.

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An Experimental Study on Seismic Performance of Precast Segmental PSC Bridge Piers with Precast Footings (프리캐스트 기초부를 갖는 조립식 PSC 교각의 내진성능에 관한 실험적 연구)

  • Kim, Tae-Hoon;Park, Se-Jin;Kim, Young-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.451-452
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    • 2009
  • The purpose of this study was to investigate the seismic performance of precast segmental PSC bridge piers with precast footings. A model of precast segmental PSC bridge piers with precast footings was tested under a constant axial load and a cyclically reversed horizontal load.

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Study on Safety Evaluation of the Half-Depth Precast Deck with RC Rib Pannel for the Flexural Behavior (리브 형상을 갖는 반단면 프리캐스트 판넬의 휨 안전성 평가 연구)

  • Hwang, Hoon Hee
    • Journal of the Korean Society of Safety
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    • v.34 no.4
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    • pp.76-84
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    • 2019
  • The precast pannels are used as formwork in Half-depth precast deck systems. Therefore, it has many advantages, including safe and convenient construction and reduced construction period compared to cast-in-place construction method. In half-depth precast deck systems, the bonding of precast pannels to cast-in place concrete is very important. To enhance the performance of half-depth precast deck system, it is necessary to improve the composite efficiency of the interface or increase the stiffness of the precast pannel to reduce deformation or stress on the interface. In this study, a flexural test of half-depth precast deck system was performed, in which the shear connecting reinforcement was applied to increase the bonding performance at the interface, and the rib shape precast panels were applied to improve stiffness. In addition, the safety and serviceability of these systems were evaluated. Test results show that all of specimens have the required flexural strength under the ultimate strength limit design. It was also evaluated to have sufficient safety for the serviceability of deflection and crack under the serviceability limit design.

Development of Precast deck Joint System (새로운 형식의 Precast 바닥판 연결방법 개발)

  • 주봉철;김영진;김병석;류형근;김덕진
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.469-474
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    • 2003
  • Recently, to overcome the disadvantages of RC decks, advanced countries such as Japan and USA, and Europe are using prestressing connection precast decks and loop connection precast decks. The prestressing connection precast deck, however, has a weakness against steel corrosion, because of unreliable enforced grouting. The relatively low loading and fatigue capacities of the loop connection precast deck make it difficult to be used for the bridge that requires high fatigue resistance due to the frequent over loaded vehicles. This research proposes the improved connecting method for the precast decks to minimize its shortcomings based on both numerical analyses and full scale model tests. The proposed method maximizes the advantages of precast decks and extends it's service life.

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Evaluation on Structural Performance of Joint with Asymmetric Ribbed Connection Details used in Precast Bridge Deck (비대칭 격벽단면을 갖는 프리캐스트 바닥판 이음부의 구조성능 평가)

  • Chung, Chul-Hun;Byun, Tae-Kwan;Kim, In-Gyu;Shin, Dong-Ho;Lee, Han-Joo
    • Journal of the Korea Concrete Institute
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    • v.29 no.2
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    • pp.159-167
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    • 2017
  • A precast concrete deck system is considered an effective alternative in terms of its rapid construction and quality assurance than cast-in-place concrete deck. In precast concrete deck system, structural performance and serviceability are mostly determined by the connection methods between the precast decks. This research proposes more improved precast deck system with asymmetric ribbed connection details improving the disadvantage of previous precast deck system such as difficulties in assembling precast decks. And in this precast deck system, a separate form is not required at the site because partition wall of the precast decks serves as a form when placing non-shrinkage mortar in the connection part of the precast decks. Therefore, rapid construction is possible. Flexural performance is verified through load tests considering main parameter such as rib length in the precast deck connection. From the test results, it can be inferred that the development of the rebar and prevention of adhesion failure in the partition wall of the precast deck system are important factors in securing the flexural performance. Although the structural performance of the precast deck system with asymmetric connection details is gradually reduced as the rib length in the precast deck connection increases, the proposed precast deck system shows sufficient flexural performance and can be applied to the connection part of precast decks effectively.

Study on Hydration Properties of High Strength Mass Concrete to apply Precast Concrete (PC 적용을 위한 고강도 매스콘크리트의 수화특성에 관한 연구)

  • Park, Heung-Lee;Kim, Sung-Jin;Lee, Hoi-Keun;Lee, Seung-Hoon;Park, Byung-Keun;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.661-664
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    • 2008
  • As architectures have recently become high-risers and megastructured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but also internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete for precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

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