Higher-Order Effects in Biaxial Flexure of GFRP I-Section Beams


  •   Zia Razzaq

  •   Faridoon Z. Razzaq


A theoretical study of Glass Fiber Reinforced Polymer (GFRP) beams subjected to biaxial bending moments is presented with a focus on the influence of higher-order effects on maximum normal stresses. It is shown that the biaxial bending type of loading causes a dramatic increase in the maximum normal stress for a GFRP beam when induced torsional effects are included. The study demonstrates that the traditional first-order theory can grossly underestimate the maximum normal stress in a GFRP beam. Based on the numerical results presented using a higher-order theory which also accounts for induced warping normal stresses, the maximum normal stress is found to be about two to three times larger than that determined using the first-order theory.

Keywords: Biaxial Flexure, Glass Fiber Reinforced Polymer (GFRP), Higher-Order Effects, I-Section Beams


Pre-Standard for Load & Resistance Factor Design (LRFD) of Pultruded Fiber Reinforced Polymer (FRP) Structures. American Society of Civil Engineers to American Composites Manufacturers Association (ACMA); 2010. Available from: http://dev1.kreysler.com/information/specifications/specs-resources/LRFD%20PreStandard%20-%20Revised%20FINAL%20-%20Nov%209%202010.pdf.

Razzaq Z, Sirjani MB. Unsymmetric bending of FRP angle sections. Proceedings of the 11th International Conference on Composites/Nano Engineering (ICCE/11), Hilton-Head, South Carolina, 2004.

Sirjani MB, Razzaq Z. Unsymmetric and Biaxial Bending of FRP Angle Sections. Journal of Reinforced Plastics and Composites, 2005; 24(18).

Gyebi KM, Razzaq Z. Glass Fiber Reinforced Polymer (GFRP) angle-section member under biaxial flexure. Proceedings of the 2nd International Conference on Composites, Porto, Portugal; 2016.

Sirjani MB, Razzaq Z. Combined Biaxial Bending and Torsion of FRP I-Section Members at Cracking. Proceedings of the 14th International Conference on Composites/Nano Engineering (ICCE/14), Boulder, Colorado; 2006.

Galambos TV. Structural Members and Frames. Englewood Cliffs, NJ: Prentice-Hall, Inc.; 1968.

Knorowski J, Bondi SB, Razzaq Z. Lateral-torsional instability and biaxial bending of FRP I-beams. European Journal of Engineering and Technology Research, 2022;7(6):29-34.


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How to Cite
Razzaq, Z. and Razzaq, F.Z. 2023. Higher-Order Effects in Biaxial Flexure of GFRP I-Section Beams. European Journal of Engineering and Technology Research. 8, 2 (Mar. 2023), 16–18. DOI:https://doi.org/10.24018/ejeng.2023.8.2.2967.

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