Buckling resistance of pultruded FRP profiles under pure compression or uniform bending - numerical simulation

The buckling-mode interaction in wide-flange pultruded fibre-reinforced plastic (PFRP) columns under pure compression is investigated in the first part of the paper through a nonlinear finite element analysis. The sensitivity to straightness, flatness and angularity tolerances reported by the pultruders is analyzed. The numerical results show that the imperfection amplitude plays a crucial role. Moreover, stocky members exhibit a stable postbuckling behaviour affected by the material strength. In the second part of the paper, an incremental finite element analysis is used to investigate the response of imperfect PFRP beams under uniform bending in the major-axis plane. For low imperfection amplitudes, the buckling-mode interaction does not influence the beam response significantly. A simple closed-form expression for the rotational spring stiffness reproducing the web-flange junction is finally proposed.