Torsional and flexural buckling of composite FRP columns with cruciform sections considering local instabilities

In this paper, a semi-analytical finite strip method is developed for the prediction of torsional and flexural buckling stresses of composite FRP columns under pure compression. Numerical finite strip results will be compared with those obtained from closed-form equations for doubly symmetric open thin-walled FRP sections. The accuracy of the proposed finite strip method in determining critical flexural and torsional stresses of FRP columns will be assessed. Among the composite FRP columns with doubly symmetric open sections, buckling behavior of stiffened and unstiffened FRP cruciform sections will be evaluated and case studies performed. The effect of material properties and longitudinal stiffeners applied at the end of the web-plate and flange-plate on buckling modes of composite FRP cruciform sections is also reviewed.