Failure modes of bonded wrapped composite joints for steel circular hollow sections in ultimate load experiments

The concept of an innovative bonded joining technology where welding is not required presented as alternative to traditional welded connection for steel circular hollow section (CHS). Wrapped composite joints have potential greatly improve fatigue endurance when applied in multi-membered truss structures, e.g. offshore jackets wind turbines. This paper focuses on characterization resistance and understanding failure modes wrapped static experiments, the prerequisite harvesting its high endurance. at two scales with different angles X-joint geometry are made GFRP material around sections without welding, tested 3 monotonic loading cases, tensile, compression in-plane bending, until failure. Counterpart smaller scale stiffness, elastic limit ultimate load comparisons. Two general joints, debonding fracture identified quantified by surface strain measurements through 3D digital image correlation (DIC) technique. Testing results indicate that 30% 56% larger stiffness 3% 68% compared counterparts. Debonding final pull-out brace member from wrap predominant mode tensile experiments both while cracking governing bending experiment. In compressive exceeds yield CHS indicating opportunity optimize wrapping thickness length.