• Title, Summary, Keyword: composite beams

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A simplified approach for fire-resistance design of steel-concrete composite beams

  • Li, Guo-Qiang;Wang, Wei-Yong
    • Steel and Composite Structures
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    • v.14 no.3
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    • pp.295-312
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    • 2013
  • In this paper, a simplified approach based on critical temperature for fire resistance design of steel-concrete composite beams is proposed. The method for determining the critical temperature and fire protection of the composite beams is developed on the basis of load-bearing limit state method employed in current Chinese Technical Code for Fire safety of Steel Structure in Buildings. Parameters affecting the critical temperature of the composite beams are analysed. The results show that at a definite load level, section shape of steel beams, material properties, effective width of concrete slab and concrete property model have little influence on the critical temperature of composite beams. However, the fire duration and depth of concrete slab have significant influence on the critical temperature. The critical temperatures for commonly used composite beams, at various depth of concrete and fire duration, are given to provide a reference for engineers. The validity of the practical approach for predicting the critical temperature of the composite beams is conducted by comparing the prediction of a composite beam with the results from some fire design codes and full scale fire resistance tests on the composite beam.

Analysis of Structural Performance of Wood Composite I and Box Beam on Cross Section Component (II) - Calculation and Analysis of Ultimate Loads - (단면구성요소(斷面構成要素)에 관(關)한 목질복합(木質複合) I 및 Box형(形) 보의 구조적(構造的) 성능(性能) 분석(分析) (II) - 최대하중(最大荷重)의 계산(計算) 및 해석(解析) -)

  • Oh, Sei-Chang;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.19 no.3
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    • pp.62-71
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    • 1991
  • An evaluation of bending test of composite I and Box beams for determining the ultimate strength limit design criteria was presented. Maxium loads of composite I beams were found in beams composed of thicker upper flanges and/or vertical LVL flanges. These loads of plywood web beams were greater than those of PB web beams. Maximum loads of unsymmetrical box beams were less than those of symmetrical box beams. Thus, it took on different phase in box type beams. Ultimate loads of composite beams were greater than those of solid. The failure of composite beams were abrupt and failure mode was classified into following categories; Edgewise shear failure in web, delamination in flange-web joint, tension failure and tearing in LVL flanges, and web delamination. These failures of composite beams were appeared at the mixed mode. The influence factor affecting the performance of tested composite beams was shear strength of PB-web composite beams and compressive strength in plywood-web composite beams. It was also assumed that the influence factors on structural performance on composite beams were flange quality, web material and geometry of cross section. As one of the design methods resisting to compressive stress that was required in the case of small span to depth ratio and deep beams. composite I-beams composed of thicker upper flanges comparing to lower flanges were very effective in structural performance.

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Analysis of Structural Performance of Wood Composite I and Box Beam on Cross Section Component (I) - Calculation and Analysis of Flexural Rigidity and Deflection - (단면구성요소(斷面構成要素)에 관(關)한 목질복합(木質複合) I및 Box형 보의 구조적(構造的) 성능(性能) 분석(分析) (I))

  • Oh, Sei-Chang;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.19 no.2
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    • pp.40-55
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    • 1991
  • To investigate the influence of cross section geometries on the behavior of composite beams in the case of small span to depth ratio and deep beams. the static flexural behavior of composite I-beams and Box- beams was evaluated. 12 types of composite I -beams composed of LVL flanges and particleboard or plywood web and 3 types of composite Box-beams composed of LVL flanges and plywood web were tested under one-point loading. The load-deflection curves were almost linear to failure, therefore, the behavior of tested composite beams was elastic. The theoretical flexural rigidity of composite beams was calculated and compared with observed flexural rigidity. The highest value was found in I-W type beams and the lowest value was found in G-P type beams. The difference between theoretical and observed flexural rigidity was small. Theoretical total deflection of tested composite beams was calculated using flexural rigidity and compared with actual deflection. Shear deflection of these beams was evaluated by the approximation method, solid crosss section method and elementary method. The difference between actual deflection and expected deflection was not found in D, E and F type beams. This defference was small in G, H and I type beams or Box-beam.

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Behaviors of CAD and CUS Thick-walled Composite I-Beam Under Torsional Load (비틀림 하중을 받는 두꺼운 복합재료 빔의 거동)

  • Park, Mi-Jung;Chun, Heoung-Jae;Byun, Jun-Hyung
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.202-206
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    • 2005
  • Most of studies on the open section composite beams are confined to the thin composite beams. There are some works focused on the thick composite beams but they are limited only to closed section beams. Therefore, it is required to develop an appropriate model to analyze the thick open section composite beams. In this study, the cantilever beams of two specific lay-up configurations are considered which are the circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) beams. Under the torsional loading, loading induced deformations are obtained for the thick beams using the suggested model. The model includes coupled stiffness and secondary warping effects. The results are compared with those obtained using thin beam model to observe the thickness effects. Those results are also compared with the finite element analysis results.

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Experimental study of moment redistribution and load carrying capacity of externally prestressed continuous composite beams

  • Chen, Shiming;Jia, Yuanlin;Wang, Xindi
    • Structural Engineering and Mechanics
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    • v.31 no.5
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    • pp.605-619
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    • 2009
  • A comparative experimental study of prestressed continuous steel-concrete composite beams was carried out. Two continuous composite beams were tested, one of which was plain continuous steel-concrete composite beam, while the other was a composite beam prestressed with external tendons. Cracking behavior and the load carrying capacity of the beams were investigated experimentally. Full plasticity was developed in the mid-span section each beam, the maximum moments attained at the internal support sections however were governed by local buckling which was related to the slenderness of composite section. It was found that in hogging moment regions, the ultimate resistance of an externally prestressed composite beam would be governed by either distortional lateral buckling or local buckling, or interactive mode of these two buckling patterns. The results show that exerting prestressing on a continuous composite beam with external tendons will increase the extent of internal force and moment redistribution in the beam. The influences of local and distortional buckling on the behaviors of the composite continuous beams are discussed. The Moment redistribution and the load carrying capacity of the prestressed continuous composite beams are evaluated, and it is found that at the ultimate state, the moment redistribution in the prestrssed continuous composite beams is greater than that in non-prestressed composite beams.

Flexural behavior of cold-formed steel concrete composite beams

  • Valsa Ipe, T.;Sharada Bai, H.;Manjula Vani, K.;Zafar Iqbal, Merchant Mohd
    • Steel and Composite Structures
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    • v.14 no.2
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    • pp.105-120
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    • 2013
  • Flexural behavior of thin walled steel-concrete composite sections as cross sections for beams is investigated by conducting an experimental study supported by applicable analytical predictions. The experimental study consists of testing up to failure, simply supported beams of effective span 1440 mm under two point loading. The test specimens consisted of composite box and channel (with lip placed on tension side and compression side) sections, the behavior of which was compared with companion empty sections. To understand the role of shear connectors in developing the composite action, some of the composite sections were provided with novel simple bar type and conventional bolt type shear connectors in the shear zone of beams. Two RCC beams having equivalent ultimate moment carrying capacities as that of composite channel and box sections were also considered in the study. The study showed that the strength to weight ratio of composite beams is much higher than RCC beams and ductility index is also more than RCC and empty beams. The analytical predictions were found to compare fairly well with the experimental results, thereby validating the applicability of rigid plastic theory to cold-formed steel concrete composite beams.

Study on stiffness deterioration in steel-concrete composite beams under fatigue loading

  • Wang, Bing;Huang, Qiao;Liu, Xiaoling;Ding, Yong
    • Steel and Composite Structures
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    • v.34 no.4
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    • pp.499-509
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    • 2020
  • The purpose of this paper is to investigate the degradation law of stiffness of steel-concrete composite beams after certain fatigue loads. First, six test beams with stud connectors were designed and fabricated for static and fatigue tests. The resultant failure modes under different fatigue loading cycles were compared. And an analysis was performed for the variations in the load-deflection curves, residual deflections and relative slips of the composite beams during fatigue loading. Then, the correlations among the stiffness degradation of each test beam, the residual deflection and relative slip growth during the fatigue test were investigated, in order to clarify the primary reasons for the stiffness degradation of the composite beams. Finally, based on the stiffness degradation function under fatigue loading, a calculation model for the residual stiffness of composite beams in response to fatigue loading cycles was established by parameter fitting. The results show that the stiffness of composite beams undergoes irreversible degradation under fatigue loading. And stiffness degradation is associated with the macrobehavior of material fatigue damage and shear connection degradation. In addition, the stiffness degradation of the composite beams exhibit S-shaped monotonic decreasing trends with fatigue cycles. The general agreement between the calculation model and experiment shows good applicability of the proposed model for specific beam size and fatigue load parameters. Moreover, the research results provide a method for establishing a stiffness degradation model for composite beams after fatigue loading.

Shear lag effect in steel-concrete composite beam in hogging moment

  • Luo, Da;Zhang, Zhongwen;Li, Bing
    • Steel and Composite Structures
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    • v.31 no.1
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    • pp.27-41
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    • 2019
  • Shear lag effect can be an important phenomenon to consider in design of the steel-concrete composite beams. Researchers have found that the effect can be strongly related with the moment distribution, the stiffness and the ductility of the composite beams. For continuous composite beams expected to sustain hogging moment, the shear lag effect can be more distinct as cracking of the concrete slab reduces its shear stiffness. Despite its influences on behaviour of the steel-concrete composite beams, a method for calculating the shear lag effect in steel-concrete composite beams sustaining hogging moment is still not available. Shear lag effect in steel-concrete composite beams sustaining hogging moment is investigated in this paper. A method was proposed specifically for predicting the effect in the cracked part of the steel-concrete composite beam. The method is validated against available experimental data. At last, FE studies are conducted for steel-concrete composite beams with different design parameters, loading conditions and boundary conditions to further investigate the shear lag effect and compare with the proposed method.

Experimental study on flexural strength of modular composite profile beams

  • Ahn, Hyung-Joon;Ryu, Soo-Hyun
    • Steel and Composite Structures
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    • v.7 no.1
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    • pp.71-85
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    • 2007
  • This study suggests modular composite profile beams, where the prefab concept is applied to existing composite profile beams. The prefab concept produces a beam of desired size having two types of profile: side module and bottom module. Module section will improve construction efforts because it offers several benefits : reduction of deflections due to creep and shrinkage, which might be found in existing composite profile beams; increase in span/depth ratio; and free prefabrication of any required beams. Based on the established analysis theory of composite profile beams, an analysis theory of modular composite profile beams was suggested, and analysis values were compared with experimental ones. The behavior of individual modules with increase of load was measured with a strain gauge, and the shear connection ratio between modules was analyzed by using the measured values. As a result of experiment, it was found that theoretical flexural strength on condition of full connection was 57%-80% by connection of modules for each specimen, and it is expected that flexural strength will approximate the theoretical levels through further module improvement.

Experimental studies on composite beams with high-strength steel and concrete

  • Zhao, Huiling;Yuan, Yong
    • Steel and Composite Structures
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    • v.10 no.5
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    • pp.373-383
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    • 2010
  • This paper presents the experimental studies of the flexural behavior of steel-concrete composite beams. Herein, steel-concrete composite beams were constructed with a welded steel I section beam and concrete slab with different material strength. Four simply supported composite beams subjected to two-point concentrated loads were tested and compared to investigate the effect of high strength engineering materials on the overall flexural response, including failure modes, load deflection behavior, strain response and interface slip. The experimental results show that the moment capacity of composite beams has been improved effectively when high-strength steel and concrete are used. Comparisons of the ultimate flexural strength of beams tested are then made with the calculated results according to the methods specified in guideline Eurocode 4. The ultimate flexural strength based on current codes may be slightly unconservative for predicating the moment capacity of composite beams with high-strength steel or concrete.