Buckling and Postbuckling Finite-Element Analysis of Pultruded FRP Profiles under Pure Compression

摘要

Results of nonlinear finite-element analyses of commercial pultruded fiber-reinforced plastic (PFRP) I-section profiles subjected to pure compression are presented. One narrow flange and four wide flange shapes are analyzed for 10 values of the column slenderness, involving 50 finite-element (FE) models. The imperfection sensitivity is investigated with reference to different imperfection shapes. For wide flange columns, if the imperfection amplitudes are identified with the limiting amplitudes reported by the pultruders, extremely low ultimate axial loads are obtained, associated with unrealistic failure mechanisms and strong interaction between local and global buckling modes. In contrast, reduced imperfection amplitudes reported in the literature lead to well documented failure mechanisms and to a small influence of the buckling mode interaction. As is known, the local buckling of wide flange shapes is triggered by the flange instability. Conversely, the local buckling of narrow flange shapes generally is triggered by the web instability. Because of this property, the paper shows that at equal cross section area, the narrow flange profiles may exhibit higher ultimate loads with respect to the wide flange profiles in a broad range of column slenderness.