Flexural and torsional properties of pultruded fiber reinforced plastic I-profiles

Experimental determination of the full section flexural and torsional properties of pultruded fiber reinforced plastic I-profiles is described. Based on beam theory approximations, test configurations for determining the various section properties are established. Tests were conducted on three different I-profiles with a range of span-to-depth ratios. Major and minor axis flexural rigidities and flexural moduli, determined from three- and four-point bending tests, show close correlation. Major and minor axis transverse shear rigidities and shear moduli show significant variation, due to differing effective areas of the cross section resisting transverse shear and differing fiber content and orientation in the web and flanges. St. Venant torsional shear moduli, determined from uniform torsion tests, are consistent but significantly greater than the transverse shear moduli, which may be due to variations in fiber content, orientation, and lay up. Warping torsional rigidities, determined from nonuniform torsion tests, are consistent with values deduced from minor axis flexural rigidities, indicating that the influence of shear deformation on restrained torsional warping is insignificant.