A finite strip method is presented for predicting local, distortional and lateral buckling of composite FRP structural plates. Each plate may be subjected to a combination of longitudinal compression, longitudinal in-plane bending and shear. A sinusoidal function assumed in the longitudinal direction for buckling mode of whatever type, and polynomial function used in the transversal direction. The critical stresess and critical moment of I-shape, Box, Channel and Monosymetric I-shape sections under bending, uniform and shear loading were obtained by solving an eigenvalue problem. Using this solution technique, simple expression for prediction of I-shape section beam’s buckling stress are presented in design curves. The critical stresses for different E x /E y are calculated using these design curves. Furthermore, bending and shear interaction evaluated by using the complex finite strip method. Critical stress of torsional and lateral buckling of I-shape sections and torsional buckling of cross sections are determined by solving the differential equation and using finite strip method. Finally the finite strip method is used to study local buckling of I-sections containing a longitudinal stiffener attached to the web. The optimum position of this stiffener is calculated to maximize the web local buckling stress.
