Experimental investigation on the structural behaviour of novel non-metallic pultruded circular tubular GFRP T-joints under axial compression

Different uniplanar T-joints made from pultruded glass-fibre reinforced polymer (GFRP) circular tubular sections (CHS) incorporating different innovative non-corrosive reinforcements with structural adhesives, carbon-fibre laminates (CFRP) and concrete-filled GFRP rods were developed, and their structural performance was tested under axial compression. The hollow T-joints without any connection reinforcements displayed brittle failure with out of plane longitudinal shear failure while the ones reinforced with CFRP and concrete-filled GFRP rods shows superior ultimate strength and ductility with diverse failure modes including interlaminar failure within the pultruded chord. With CFRP wrapping and concrete filling, increases in strength and ductility of up to eightfold and fortyfold were seen, respectively. Design oriented equations and analytical formulations were developed for the T-joints and their predictions were compared with experimental results. These novel connections presented in this study are recommended for future construction of offshore tubular structures.