Flexural–torsional buckling of fiber-reinforced plastic composite cantilever I-beams

Department of Civil Engineering, Auburn Science and Engineering Center, The University of Akron, Akron, OH 44325-3905, USA
Composite Structures (Impact Factor: 3.32). 05/2003; 60(2):205-217. DOI: 10.1016/S0263-8223(02)00304-5

ABSTRACT A combined analytical and experimental study of flexural–torsional buckling of pultruded fiber-reinforced plastic (FRP) composite cantilever I-beams is presented. An energy method based on nonlinear plate theory is developed for instability of FRP I-beam, and the formulation includes shear effect and bending–twisting coupling. Three different types of buckling mode shape functions of transcendental function, polynomial function, and half simply supported beam function, which all satisfy the cantilever beam boundary conditions, are used to obtain the eigenvalue solution, and their accuracy in the analysis are investigated in relation to finite element results. Four different geometries of FRP I-beams with cantilever beam configurations and with varying span lengths are experimentally tested under tip loads to evaluate their flexural–torsional buckling response. The loads are applied at the centroid of the tip cross-sections, and the critical buckling loads are obtained by gradually adding weight onto a loading platform. A good agreement among the proposed analytical solutions, experimental testing, and finite element method is obtained, and simplified explicit formulas for flexural–torsional buckling of cantilever beams with applied load at the centroid of the cross-section are developed. The effects of vertical load position through the cross-section, fiber orientation and fiber volume fraction on buckling behavior are also studied. The proposed analytical solutions can be used to predict the flexural–torsional buckling loads of FRP cantilever beams and to formulate simplified design equations.

279 Reads
  • Source
    • "Some studies were performed to investigate the local buckling and lateral-torsional buckling of beams under transverse load [22] [23] [24] [25] [26] [27] [28] [29] [17] [30] [31] [32] [33] [34] [35] [36]. A study examined the shear deformability of a beam with a U-section under transverse load is found [37]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: This study investigates the replacement of traditional materials (steel, wood and concrete) in electricity transmission lines by fiber glass pultruded members. The first part of the study summarizes a comparison between different design approaches to experimental data for glass fiber pultruded sections. For this purpose, a total of fifteen specimens made of E-glass and either polyester or vinylester matrix are tested: (i) angle-section, square-section and rectangular-section specimens are subjected to axial compression; (ii) I-section and W-section specimens are tested under bending. The experimental results are summarized in terms of the failure mode, critical buckling load and load–displacement relationships. Design equations available in FRP design manuals and analytical methods proposed in the literature are used to predict the critical buckling load and compared to the experimental results. Design of various FRP pultruded sections and cost estimate are conducted for 69 kV electricity transmission portal frame and a total distance of 10 km. The significance of the present findings with regard to economic solutions is discussed.
    Composite Structures 05/2013; 105:408-421. DOI:10.1016/j.compstruct.2013.05.025 · 3.32 Impact Factor
  • Source
    • "He analysed the effect of the load position on the lateral buckling behaviour and found out that the buckling loads provided by available analytical formulae underestimate the experimentally obtained values by as much as 55% – Turvey attributed these differences to possible inaccuracies in estimating the inplane shear modulus, pre-buckling deformations and/or other geometrically nonlinear effects. Tests on I-section cantilevers with four different NF and WF cross-sections loaded at the shear centre were reported by Qiao et al. [24] – although these authors obtained a good agreement between the experimental and analytical critical loads (the latter yielded by closed formed solutions developed by themselves), the effect of the load position was never addressed experimentally. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Although fibre reinforced polymers exhibit several advantages over traditional materials, their widespread acceptance is being delayed by the lack of appropriate design codes. In fact, additional and comprehensive experimental data are needed to assess the accuracy of recently developed analytical and numerical design tools. This work reports an experimental study on the first-order, buckling and post-buckling behaviours of I-section beams made of GFRP pultruded profiles. Tests were first carried out on small-scale (coupon) specimens, in order to determine the most relevant material mechanical properties. Full-scale tests were then conducted on (i) simply supported beams with spans varying from 1.0 m to 4.0 m under 3-point bending and (ii) cantilevers with spans ranging from 2.0 m to 4.0 m subjected to a tip point load applied at the end cross-section centroid or top/bottom flange mid-point. While the first series is aimed at investigating the flexural behaviour under service and failure conditions (including the local buckling of the top flange), the objective of the second series is to study the collapse behaviour stemming from lateral-torsional buckling. The results obtained confirm that, due to the GFRP low Young’s modulus and high strength, the beam structural integrity is often governed by excessive deformation and/or local and global buckling phenomena, rather than by material strength limitations. Moreover, the low shear-to-Young’s modulus ratio implies that the role played by the shear deformation is quite relevant, particularly in stocky beams. The experimental data presented here is used to validate and assess the accuracy of numerical simulations reported in a companion paper (Part 2).
    Computers & Structures 11/2011; 89(21):2052-2064. DOI:10.1016/j.compstruc.2011.07.005 · 2.13 Impact Factor
  • Source
    • "They also succeeded in developing analytical solutions in the field of flexural–torsional buckling of composite FRP members made of I and U sections [5] [6]. Silvestre and Camotim extended GBT method to analyze the local-plate, distortional and mixed flexuraldistortional buckling modes of FRP-lipped channel members [7]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a semi-analytical finite strip method is developed for the prediction of torsional and flexural buckling stresses of composite FRP columns under pure compression. Numerical finite strip results will be compared with those obtained from closed-form equations for doubly symmetric open thin-walled FRP sections. The accuracy of the proposed finite strip method in determining critical flexural and torsional stresses of FRP columns will be assessed. Among the composite FRP columns with doubly symmetric open sections, buckling behavior of stiffened and unstiffened FRP cruciform sections will be evaluated and case studies performed. The effect of material properties and longitudinal stiffeners applied at the end of the web-plate and flange-plate on buckling modes of composite FRP cruciform sections is also reviewed.
    Composite Structures 09/2011; 93(10):2575-2586. DOI:10.1016/j.compstruct.2011.04.020 · 3.32 Impact Factor
Show more