• Title/Summary/Keyword: slab deflection

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Moment curvature method for fire safety design of steel beams

  • Yu, H.X.;Richard Liew, J.Y.
    • Steel and Composite Structures
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    • v.4 no.3
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    • pp.227-246
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    • 2004
  • This paper presents a moment-curvature method that accounts for the strength deterioration of steel at elevated temperature in estimating the response of steel beams exposed to fire. A modification to the EC4 method is proposed for a better estimation of the temperature distribution in the steel beam supporting a concrete slab. The accuracy of the proposed method is verified by comparing the results with established test results and the nonlinear finite element analysis results. The beam failure criterion based on a maximum strain of 0.02 is proposed to assess the limiting temperature as compared to the traditional criteria that rely on deflection limit or deflection rate. Extensive studies carried out on steel beams with various span lengths, load ratios, beam sizes and loading types show that the proposed failure criterion gives consistent results when compared to nonlinear finite element results.

Structural Performance of Super-Deck Plate Slab System with Truss Type Bar (트러스근을 사용한 슈퍼데크 플레이트의 구조성능평가)

  • Kim, Seong-Soo;Kim, Sang-Shik;Lee, Woo-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.2
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    • pp.193-199
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    • 2003
  • This paper presents the results of an experimental research project on 7 Super Deck Plates with continuous or simple beam types. The test parameters included the distance of truss, depth of deck plate and the type of beam. The test results are as follows ; When thickness of deck plate was increased, maximum strength was improved When the distance of truss bar was reduced from 20cm to 15cm, the mean value of maximum load was increased to 1.21 times. Continuous beam shown superior to simple beam, such as 5.03 times high strength, low deflection at yield point.

Experimental Study on Behaviour of Composite Beams with Ribbed Slabs and Unreinforced Web Openings (리브형 슬래브를 갖는 유공합성보의 거동에 관한 실험적 연구)

  • 김창호;박종원;김희구;이창섭;박준용
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.10b
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    • pp.989-994
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    • 2000
  • Nine tests to failure are performed on full-scale eight composite beams with unreinforced web opening having ribbed slabs with formed deck which are perpendicular to the steel section and one steel beam. The effects of slab width, reinforcing of stud, moving of rib, moment-shear ratio are studied. At the low M/V ratio, Vierendeel action around the high moment end of the opening is occurred and the large deflection across the opening and transverse cracking are occurred with increasing of applied load. As the M/V ratio increases, the relative deflection across the opening decreases. And at failure, full tensile strain are occurred at bottom T section of steel beam, and concrete crushes at the High Moment End of the opening. With narrow slabs, diagonal tension failure at the high moment end of the opening is occurred. And with wide slabs, rib punch-through failure is occurred near the high moment end of the opening. The implications for design are discussed.

Support Deflection Effects in Slabs with Beam and Girder (보-거더 시스템 슬래브에서 지지부 처짐영향에 관한 연구)

  • 곽효경;송종영
    • Computational Structural Engineering
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    • v.11 no.1
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    • pp.237-249
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    • 1998
  • In this study the support deflection effects in beam-girder slabs which are broadly being adopted in building structures are studied for both distributed loads and concentrated vehicle loads. Taking the finite element analysis of slabs supported with one or two cross beams, the member forces of slabs including the support stiffness have been calculated. Based on the obtained numerical results and regression analysis of those, correction factors of member forces for slabs supported with girders and cross beams have been proposed. Finally, the validity of the proposed correction factors are demonstrated through a typical design example.

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A Study on Construction Sequence Optimization and Structural Analysis in consideration of Structural Concept of Hanging Structure based on the Applied Case (적용사례 중심의 매달린 구조물의 구조적 특성을 고려한 시공순서 최적화 및 시공단계별 구조해석 연구)

  • Park, Yong-Hyeon;Kim, Jong-Soo;Ju, Young-Kyu
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.7
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    • pp.147-156
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    • 2019
  • The purpose of this study is to consider structural issues and analyze construction sequences when constructing hanging floors supported by Mega truss. Since suspended structures were supported by the Mega truss, vertical load on suspended structures was needed to transfer from low to high. Deflection management of structures was the primary point under construction. The results of this study were as follows; The steel structures, which has relatively lighter self-weight, were constructed upwards after the base floor steel truss erection. Concrete Placing, which has relatively heavier self-weight, were performed in two phases to minimize structure's deflection. Slab was placed downwards from the top floor to lower floor whereas column was places upwards. Deflection measurements were carried out at every construction sequences.

Mechanical Properties of Reinforced Concrete Slabs at Early Ages (초기재령 콘크리트 슬래브의 처짐 예측)

  • 신성우;유석형;오성진;황동규;박기홍
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.397-400
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    • 2002
  • The mechanical properties of concrete such as modulus of elasticity, bond strength and shear strength are proportional to square root of compressive strength. And compressive strength of concrete is developed rapidly at early ages. Thus the relationship between compressive strength and its mechanical properties should be verified because the mechanical properties of early age concrete and hardened concrete are different. In this study, to predict the concrete slab deflection at early ages, modulus of elasticity and effective moment of inertia(Ie) are observed and compared with experimental results.

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A Study on Effect of Pre-Stressing Sequences in PSC Bridge Strengthening Method Using Continuity with External Prestressing (PSC교량 보강시 긴장력 도입순서의 영향에 관한 연구)

  • 방명석
    • Journal of the Korean Society of Safety
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    • v.16 no.4
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    • pp.123-127
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    • 2001
  • Numerous PSC bridges are stregthened by the combined use of continuity of simple spans and addition of external prestressing. In this case prestressing sequences should be carefully checked due to the effect on the stress and camber of girders and slab. Various prestressing sequences were applied in this field test and measured values were analysed. This results show that preatressing sequences affact the stress and deflection of bridge members, so the prestressing sequence should be considered at the desist and construction stages of deteriorated bridges.

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시공중인 합성바닥슬래브의 처짐보정에 대한 수치적 연구

  • 김영찬;이정헌
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 2002.05a
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    • pp.293-298
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    • 2002
  • In the composite deck system, beams and deck plates deflect during construction. This lens-shaped deflection may cause problems in the serviceability of a building. Therefore, it should be compensated to be level. Several methods for leveling of floor slab are available, such as increasing stiffness of structural members, pouring additional concrete. In this study, additional weight and volume o( concrete for level compensation are examined for various size of floors.

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Variability of Deflections for Reinforced Concrete Flat Plate (철근 콘크리트 플랫 플레이트 처짐의 변동성 평가)

  • Kim, Min Sook;Jo, Eunsun;Lee, Young Hak
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.6
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    • pp.543-549
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    • 2014
  • The deflection of reinforced concrete members can be highly variable, due to uncertainties in the characteristics of the concrete. However, current standards do not take this problem into account, instead recommending only the minimum thickness and maximum allowable deflections based on empirical data. This paper is aimed at evaluation deflection variabilities by applying a probabilistic analysis model to a finite element analysis model. To evaluate the variabilities of deflections, a Monte Carlo simulation, which incorporated the eight parameters related to concrete, reinforcement, member size, and tension stiffening. The results showed that lager spans were more sensitive to the deflection due to loads and that as the applied live loads were increases and the slab thickness were decreased, the deflection variability increased.

Evaluation Techniques for Residual Structural Performance of a Reinforced Concrete slab under Fire Damage (화재 피해를 입은 철근콘크리트 슬래브의 잔존 구조성능 평가기법)

  • Choi, Kwang-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.588-594
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    • 2020
  • This study proposes non-destructive rebound-hardness and ultrasonic testing methods to more accurately evaluate the residual structural performance of reinforced concrete structures in a fire. Techniques are also proposed to assess the stiffness used in the deflection calculation with natural frequencies obtained by vibration tests. In the compressive strength evaluation using rebound hardness, the residual compressive strength of thick specimens and a larger water/cement (W/C) ratio were shown to be large. The homogeneity of concrete at high temperature compared to ambient temperature conditions was assessed by the velocity of ultrasonic waves that penetrate the concrete, and it followed W/C or thickness of slab makes little different results. To assess the stiffness of fire-damaged slabs and increase in deflection, the natural frequency was measured by vibration tests and incorporated into the equation of the stiffness. The application of this technique to the slab experiment showed that it can be a very reasonable evaluation technique. In addition, to evaluate the residual strength of a member after fire, a test of the strength of a component was carried out during and after heating.