Experimental and numerical study on the structural behavior of eccentrically loaded GFRP columns

Glass fiber reinforced polymer (GFRP) pultruded profiles are being increasingly used in civil engineering applications. Although they offer several advantages over traditional materials, such as high strength, lightness and non-corrodibility, GFRP profiles present low elasticity and shear moduli, which together with their slender walls makes them very prone to buckling phenomena. Several previous studies addressed the global and local buckling behavior of GFRP pultruded members under concentric loading. However, little attention has been given to the effect of small eccentricities, which may arise from material geometrical imperfections or construction errors. This paper presents results of experimental and numerical investigations about the structural behavior of GFRP pultruded columns subjected to small eccentric loading about the major (strong) axis. To accomplish such goal, three series of 1.50m long GFRP I-section (120×60×6mm) columns were tested in compression applied with the three following eccentricity/height of the cross-section ratios: e/h=0.00, 0.15 and 0.30. It was found that such small eccentricities are of major importance for the behavior of GFRP pultruded columns. Although the initial axial stiffness of eccentrically loaded columns was similar to that of concentrically loaded ones, for increasing loads the stiffness considerably decreased due to bowing and second-order P–δ effects. Furthermore, results show that the load capacity of columns subjected to loads applied within the kern boundaries is reduced up to 40% at an approximately linear trend. Results obtained from the experimental campaign were compared with analytical predictions and numerical simulations using (i) the finite element method (FEM) and (ii) the generalized beam theory (GBT). In general, a very good agreement was obtained between experimental data and analytical and numerical results.