• Title/Summary/Keyword: LB-DECK panel

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A Study on the Structural Behavior of LB-DECK Panel Considering Rebar-Arrangement in Site (현장 배근이 LB-DECK 패널의 구조거동에 미치는 영향)

  • Lho, Byeong-Cheol;Cho, Gyu-Dae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.3
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    • pp.167-174
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    • 2008
  • The objective of this study is to verify whether the composite action is sufficiently strong to withstand at the interface and the structural behavior of LB-DECK panel with field concrete slab strengthened with main reinforcing bars. Static and fatigue tests are performed for LB-DECK panels with varied shapes and amounts of rebars, and the results are compared with those of field concrete panel(FCP). The test results indicate that the LB-DECK panel with 1.5 times of more rebars inside significantly increase the overall stiffness. LB-DECK penel usually shows on average 52.1 percent of improved stiffness compared with the FCP. The fatigue test results also show that the LB-DECK panel can withstand two-million cycles of repeated loads without any damage.

A Study on Constructability Improvement of LB-DECK Panel (LB-DECK 패널의 시공성 향상에 관한 연구)

  • Cho, Hyun-Chul;Lho, Byeong-Cheol;Cho, Gyu-Dae;Choi, Kyu-Hyung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.2 s.54
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    • pp.122-128
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    • 2009
  • This study is to improve constructability of LB-DECK construction in site such as inconvenience of main and distribution bars in arrangements LB-DECK Panel which is work is applied to many bridges these days as a permanent formwork. So, the constructability is improved by changing the method of allocation of main reinforcing bar and distribution bar which is reviewed for improving efficiency of design and construction process among the suggested methods. The crack shapes, deflections, and strains under static load of the improvement of LB-DECK Panel are compared and analyzed to former LB-DECK Panel. As a result, 13% of strength compared to before the improvement of LB-DECK Panel, and 10% of strength is increased in the case of slab.

Experimental Study on the Cracking Loads of LB-DECKs with Varied Cross-Section Details (단면 상세가 변화된 LB-DECK의 균열하중에 대한 실험적 연구)

  • Youn, Seok-Goo;Cho, Gyu-Dae
    • Journal of the Korea Concrete Institute
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    • v.23 no.5
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    • pp.657-665
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    • 2011
  • LB-DECK, a precast concrete panel type, is a permanent concrete deck form used as a formwork for cast-in-place concrete pouring at bridge construction site. LB-DECK consists of 60 mm thick concrete slab and 125 mm height Lattice-girders partly embedded in the concrete slab. These decks have been applied to the bridges, which girder spacings are short enough to resist longitudinal cracking caused by construction loads. This paper presents experimental research work conducted to evaluate the cracking load of LB-DECKs designed for long span bridge decks. Twenty four non-composite beams and four composite beams are fabricated considering three design variables of thickness of concrete slab, height of lattice-girder, and diameter of top-bar. Static loads controlled by displacements are applied to test beams to obtain cracking and ultimate loads. Vertical displacements at the center of beams, strains of top-bar, crack propagation in concrete slab, and final failure modes are carefully monitored. The obtained cracking loads are compared to the analytical results obtained by elastic analyses. Long-term analyses using age-adjusted effective modulus method (AEMM) are also conducted to investigate the effects of concrete shrinkage on the cracking loads. Based on the test results, the tensile strength and the design details of LB-DECKs are discussed to prevent longitudinal cracking of long span bridge decks.

Micro-Cracks Control of LB-DECK Using Polymer Cement Concrete (폴리머 시멘트 콘크리트를 이용한 LB-DECK의 미소균열 제어)

  • Lho, Byeong-Cheol;Choi, Jong-Yun;Cho, Gyu-Dae;Choi, Jong-Gwon
    • Journal of the Korea Concrete Institute
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    • v.24 no.2
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    • pp.103-109
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    • 2012
  • Micro-cracks with a width less than 0.1 mm in precast concrete panels do not cause structural problem, but they can cause problems in long term durability and concrete surfaces aesthetic, requiring additional repair costs. In this paper, polymer cement concrete is used to increase flexural tensile strength and to prevent micro-cracks due to construction loads on LB-DECK panels. Using 5% polymer-cement ratio, the panel crack moment is increased by improving flexural tensile strength and controlling visible micro-cracks during construction stage of LB-DECK.

Development of Short-span Precast Concrete Panels for Railway Bridge (철도교용 단지간 프리캐스트 콘크리트패널의 개발)

  • Seol, Dae-Ho;Lee, Kyoung-Chan;Kim, Ki-Hyun;Youn, Seok-Goo
    • Journal of the Korea Concrete Institute
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    • v.28 no.5
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    • pp.545-553
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    • 2016
  • This paper presents experimental static test results of the precast concrete panels developed for short-span concrete bridge deck form. Different from LB-DECK, concrete rib attached to the bottom surface of concrete panel, and Top-bar is not used at the top surface of concrete panel. Number of concrete ribs and cross-section details of concrete rib are determined from the analytical results of parametric study considering the span length and the thickness of concrete bridge decks. Shear rebars are installed at the top surface of concrete panel for composite action between precast concrete panel and cast-in-place concrete. In order to evaluate the safety and the serviceability of the developed short-span concrete panel subjected to design load, static load test is conducted. Three test panels with span length of 1.6m are fabricated, and during the load test displacements, strains and cracks of test panels are measured and final failure modes are investigated. Serviceability of the test panels is evaluated based on the results of displacements, cracking load, and crack width at the design load level. Safety is also evaluated based on the comparison of the ultimate strength and the factored design load of test panels. Based on the test results, it is confirmed the short-span precast concrete panel satisfies the serviceability and safety regulated in design codes. In addition, the range of span length of concrete bridge decks for the short-span concrete panel is discussed.