Ultimate load performance of tubular composite joints under various loading conditions

This research investigates non-welded tubular composite joints, highlighting theirpotential for offshore structures, such as wind turbine supporting jackets. These jointsface complex loading from wind, waves, and tides. These forces generate axial forcesand bending moments in the joints. tubular composite joints leverage the interfacialbonding between the composite and Circular Hollow Section (CHS) members forefficient load transfer. A critical failure mode is interfacial debonding. This paperfocuses on the characterisation and resistance of interfacial debonding in tubularcomposite joints through monotonic experiments. X90-joints are subjected to axialtension, axial compression, axial tension with out-of-plane bending (Nx+Mop), axialcompression with out-of-plane bending (-Nx+Mop), axial tension with in-plane bending(Nx+Mip), and axial tension + out-of-plane bending + in-plane bending (Nx+Mop+Mip).Experiments are performed on joints scaled to 1/4th of the real size found in typicaljacket designs. Numerical models employ cohesive zone modeling (CZM) to predictdebonding failure modes. Results from the experiments reveal that debonding failure isthe predominant mode under different loading conditions. Combined loading influencesthe sequence and extent of debonding propagation, although not affecting the primaryfailure mechanism.