Novel joint for pultruded FRP beams and concrete-filled FRP columns: Conceptual and experimental investigations

A novel joint, inspired by ancient mortise-and-tenon joints in timber structures, was proposed for pultruded FRP beams and concrete-filled FRP columns. FRP structures are widely known to lack appropriate joint solutions. In this regard, the proposed joint effectively provides a feasible solution for FRP frame structures. In this work, the conceptual development of this joint was first addressed. Then, the construction schemes were presented in detail, and a total of four full-scale joints were tested. To assess the structural behavior of the proposed joint, experiments including four specimens were conducted under symmetric and anti-symmetric load, i.e. the loading conditions in sway and non-sway frames. The typical failure modes were identified, including pull-out or tensile fracture of the tensile flanges and end crushing of the compressive flange. Additionally, an analytical study is carried out to develop the design method for this joint. The predicted moment capacity is found to have an excellent accuracy as compared to the experimental results. Moreover, the proposed joint can be classified as the rigid and full-strength joint based on the classifications prescribed by the European design code. It is noted that the proposed joint is completely composed of FRP composites and concrete (i.e., a steel-free joint). Thus, the joint is expected to exhibit excellent corrosion resistance, which is of particular interest for marine structures on/near oceans.