Measurement of the Timoshenko Shear Stiffness. I: Effect of Warping

Fiber-reinforced polymer (FRP) composite beams are increasingly finding use in construction. Due to their lower stiffness relative to steel sections, design of FRP structures is usually deflection controlled. Furthermore, shear deformation can be significant in FRP beams, thus, requiring the use of the Timoshenko beam theory to estimate deflections. However, Timoshenko shear stiffness can be difficult to measure. Part of the measurement error is attributed to shear warping effects. It has been hypothesized that warping restrains at loading points and supports increase the apparent shear stiffness to a degree that is significant at relatively short spans. In this paper, influence of warping on short to moderate length FRP beams under various types of loading and boundary conditions is considered using finite-element analysis. In particular, a commercially available thin-walled FRP beam was studied. Results suggest that warping has a negligible effect for thin-walled beams at reasonable spans. Conversely, the effective shear stiffness is found to decrease at shorter span lengths. This is the first of 2 papers in a series.

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  • Supplemental Notes:
    • Abstract reprinted with permission from ASCE
  • Authors:
    • Hayes, Michael D
    • Lesko, John J
  • Publication Date: 2007-5


  • English

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  • Accession Number: 01051324
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 10 2007 1:17PM