Postbuckling failure analysis of pultruded FRP beams under uniform bending

Abstract

The postbuckling behaviour of Pultruded Fibre-Reinforced Plastic (PFRP) beams in uniform major-axis bending is analysed through a nonlinear finite element (FE) analysis including initial out-of-straightness. Two wide-flange shapes by two pultruders are analysed for six values of the beam slenderness, involving 24 FE models. The limiting imperfection amplitudes reported by the pultruders are shown to yield extremely low ultimate bending moments, associated with unrealistic failure mechanisms and strong interaction between local and flexural–torsional buckling modes. Conversely, reduced imperfection amplitudes reported in the literature are found to lead to well documented failure mechanisms and to a small influence of the buckling mode interaction. The influence of the warping restraints at the beam end sections is also discussed.