Explicit equation for critical local buckling of thin walled FRP I-sections subjected to combined axial compression and bending

Abstract

Explicit equation for the local buckling critical stress of fibre reinforced polymer (FRP) structural profiles under combined axial compression and bending moment is proposed in this paper. The proposed equation is obtained by choosing suitable cross-sectional shape functions considering the compatibility of rotation between web and flange and by using the Rayleigh Quotient energy method. The obtained equation accounts for the difference of widths and thicknesses between web and flange and it allows to consider various orthotropy ratios. Results obtained with the analytical approach are compared with Generalized Beam Theory (GBT) for different orthotropic FRP structural I-sections. A comparison of the proposed analytical approach with respect to the finite element method was also made. From all comparisons made, for the different cases studied, the proposed equation seems to be reliable.