Bolted and bonded FRP beam-column joints with semi-rigid end conditions

Presented are test results from eight full-scale pultruded FRP beam-to-column joint subassemblies. Moment-rotation behaviour, failure modes, joint classification and load enhancement due to semi-rigid end conditions are discussed. Testing is divided in two series: first had FRP beam-to-steel column joints and second FRP beam-to-FRP column joints. The joints are either flange and web cleated or flange cleated only. The connection method is bolting or ‘hybrid’ combining both bolting and bonding. Test parameters include effects of adhesive bonding, column flexibility, cleat material and joint configuration. Bolted and bonded joints not only increased moment resistance but stiffness as well. Using steel cleats instead of FRP resulted in a 50% increase in the moment resistance. Four failure modes, shear-out failure, adhesive debonding with shear-out failure, tensile tearing of the column flanges from the web and delamination cracking of cleats were observed. All joints were classified as semi-rigid. This semi-rigid action was used to increase the beam's load carrying capacity. For a span-to-depth ratio of 20, the increase in load was 50% for the bolted case and 70% for the bolted and bonded joints. This increase provides a design flexibility to designers, who are restricted by limited off-the-shelf FRP section sizes. © 2020 Elsevier Ltd