Behavior and Design of Concentrically Loaded Pultruded Angle Struts

Abstract

This paper presents the results of a study pertaining to the short-term behavior of concentrically loaded single angle members made of pultruded fiber-reinforced polymeric materials. Seven E-glass/polyester and 18 E-glass/vinylester angle specimens having slenderness ratios ranging from 30 to 105 and leg width-to-thickness ratios of 8, 10.7, 12, 16, and 24 were tested. Tests have shown that under compression loading, pultruded angles reinforced with E-glass roving and nonwoven E-glass strand mats buckle in either flexural or flexural-torsional modes. These experimentally observed buckling modes were also predicted analytically, based on derived mathematical models that describe the buckling behavior of a specially orthotropic, centrally loaded, equal-leg angle section. Compression and in-plane shear coupon tests were conducted to characterize the material. The results were analyzed statistically to obtain the 95% lower confidence limit on the 5th percentile strength and modulus values, which in turn were used in the analytical buckling formulae to correlate the experimental to the analytical buckling loads. Finally, load and resistance factor design equations with a target reliability index of 3 for buckling and 4 for material compressive strength limit states are proposed.