• Title/Summary/Keyword: 거더 처짐

Search Result 92, Processing Time 0.02 seconds

A Study on Static and Fatigue Behavior of Restrained Concrete Decks without Rebar by Steel Strap (Steel Strap으로 횡구속된 무철근 바닥판의 정적 및 피로거동 특성 연구)

  • Jo, Byung Wan;Kim, Cheol Hwan
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.16 no.5
    • /
    • pp.137-147
    • /
    • 2012
  • In the steel-free bridge concrete deck, steel straps are generally used instead of conventional steel rebar while laterally restrained in the perpendicular direction to the traffic in order fir the arching effect of concrete deck. In this paper, the minimum amount of FRP bar is to be suggested based on the structural strength, crack propagation, stress level and others in order to control cracks. As a result of laboratory tests, the structural strength of deck with 0.15 percentage of steel strap showed improved structural strength including ductility. The long-term serviceability of steel strap deck with FRP bar proved to satisfy the requirements and to be structurally stable while showing the amount of crack and residual vertical displacement within the allowable limits after two million cyclic loadings. The structural failure of RC bridge deck is generally caused from the punching shear rather than moment. Therefore, the ultimate load at failure could be estimated using the shear strength formula in the two-way slab based on ACI and AASHTO criteria. However the design criteria tend to underestimate the shear strength since they don't consider the arching effects and nonlinear fracture in bridge deck with lateral confinement. In this paper, an equation to estimate the punching shear strength of steel strap deck is to be developed considering the actual failure geometries and effect of lateral confinement by strap while the results are verified in accordance with laboratory tests.

Behavior of RC Beam Strengthened with Advanced Lifting Hole Anchorage System (개선된 인양홀을 이용한 정착장치로 보강된 RC 보의 거동)

  • Oh, Min-Ho;Kim, Tae-Wan;Park, Sun-Kyu
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.14 no.3
    • /
    • pp.91-99
    • /
    • 2010
  • In order to strengthen RC structures, various strengthening methods have been used. Particularly, external tendon strengthening method is very popular method to strengthen damaged structures in terms of efficiency, ease, economics. In this study, improved anchorage elements using the lifting hole were proposed to strengthen PSC or RC girder without any damage. Two types of anchorage elements were proposed and these elements were applied on six RC beams. Also, three types of existing anchorage elements were applied on three RC beams. Otherwise, any anchorage element was not applied on one RC beam to used as a control beam. To analyse behavior of these elements, static load tests were carried out. Test variables were anchorage shapes, prestressing level on the steel bar and tendon profiles. Deflections, strains and modes of failure were recorded to examine the strengthening effects of the beams. Ductility index and tendon stress were analyzed by comparing cracking load, yielding load and ultimate load. As a result, proposed anchorage elements using lifting hole were superior to existing anchorage elements in terms of strengthening effect and furthermore, they showed ductile behavior based on energy method.