LOCAL BUCKLING OF FRP STRUCTURAL SHAPES - EXPLICIT ANALYSES

摘要

Pultruded Fiber-reinforced plastic (FRP) structural shapes (beams and columns) are thin-walledrnopen or closed sections consisting of assemblies of flat panels and commonly made of E-glass fibers andrnpolyester or vinylester resin. Due to the high strength-to-stiffness ratio of composites and thin-walledrnsectional geometry of FRP shapes, buckling is the most likely mode of failure before material failure. Inrnthis paper, explicit analyses of local buckling of rectangular composite plates with various unloadedrnedge boundary conditions (i.e., (1) rotationally restrained elastically along both unloaded edges and (2)rnone rotationally restrained and other free along the unloaded edges) and subjected to uniform in-planernaxial action at simply supported loaded edges are presented. A variational formulation of the Ritzrnmethod is used to establish an eigenvalue problem, and by using combined harmonic and polynomialrnbuckling deformation functions for box section and linearly combining the displacement fields of twornextreme cases of simply-free and clamped-free boundary conditions for I-section, explicit solutions ofrnplate local buckling coefficients are obtained. The two cases of elastically rotationally restrained platesrnare further treated as discrete plates or panels of fiber-reinforced plastic (FRP) closed and open sections,rnand by considering the effect of elastic restraints at the joint connections of flanges and webs, the localrnbuckling strength of FRP shapes is predicted. The theoretical predictions are in good agreements withrntranscendental solutions and finite element eigenvalue analyses for local buckling of FRP columns. Thernpresent explicit formulation can be applied to determine local buckling capacities of composite platesrnwith elastic restraints along the unloaded edges and can be further used to predict the local bucklingrnstrength of FRP shapes.