Lateral torsional buckling and section distortion of pultruded GFRP I-sections subject to flexure

摘要

Lateral torsional buckling (LTB) and local section distortion of pultruded glass fiber reinforced polymer (GFRP) I-sections subject to flexure are investigated. LTB behavior will dominate longitudinally slender beams having low flange slenderness. However, as the flange becomes more slender and/or the beam shorter, the effects of local section distortion (LSD) become significant, reducing the LTB capacity of the member. Using the energy method, an analytical study was conducted and explicit equations for predicting the critical LTB buckling moments of GFRP I-sections accounting for the effects of LSD are proposed. The proposed LTB equation was validated using experimental results and finite element analysis. Excellent agreement was observed between the proposed LTB equation and experimental results for sections expected to be dominated by LTB behavior. Extending the study using the same approach, an equation predicting LTB capacity as it is affected by LSD was also validated using experimental results. It is found that the proposed LTB equation captures the capacity reduction due to LSD and therefore, provides more accurate predictions for sections expected to be dominated by LSD behavior; those having small slenderness ratios and large flange slenderness ratios.