Enhancing flange local buckling strength of pultruded GFRP open-section beams

In this work, the use of pultruded GFRP web stiffeners to enhance the flange local buckling behavior of pultruded GFRP open-section beams was proposed and demonstrated through a numerical study. The buckling strength of the GFRP I-beam was successfully increased by up to 207% via this approach. The influences of the stiffener geometry and spacing were investigated. The buckling strength of the GFRP I-beam increased as the stiffener width increased and the stiffener spacing decreased. Epoxy adhesive was found to provide a sufficient bonding effect between the web stiffeners and the beams. In addition, a design approach was proposed to predict the increased buckling strength of GFRP I-beams strengthened with web stiffeners. A comparison with finite element analysis and experimental results showed that the design equation was able to provide uniformly conservative predictions. Additionally, practical design suggestions were provided to ensure the best performance of the web stiffeners. The strengthening approach addressed in this work could potentially permit a longer span of GFRP profiles and a wider application of GFRP structures.