A novel ductile connection for FRP pultruded beam-to-column assemblies

The resistance, stiffness and ductility of the joints between Fibre Reinforced Polymer (FRP) members play a key role in ensuring the required structural performance of pultruded composite frames. Both bonded and bolted joints are characterised by poor mechanical performance due to brittle failure and low resistance respectively. Hybrid joints are stronger and more ductile, but are still affected by some criticisms such as (i) non-repairability, (ii) the presence of holes in the fibre-reinforced material, (iii) the difficulty of assembling a transverse beam into the joint, which is typically required for real 3D systems. To overcome such limitations, a novel ductile connection has been developed by combining ductile steel elements bonded to FRP members. The steel elements are bolted together and are designed to be weaker than the FRP profiles and adhesive. Experimental tests on beam-column assemblies have been carried out and the test results have shown that the investigated hybrid connection is characterised by adequate stiffness, resistance and high ductility. The damage is concentrated in the bolted steel elements, which can be easily replaced, confirming the repairability of the assembly.