Parametric Investigation of Composite Reinforcement for Repairing Fatigue-Cracked Tubular T-Joints

For offshore jacket constructions, circular hollow sections (CHS) have been widely used due to their exceptional performance in compression and high torsional resistance. Specifically, CHS have direction-independent stiffness and drag characteristics, which provide the structure with added stability under various marine environments. Hence, CHS are commonly chosen and welded to form tubular joints. Due to the complex geometry of the joints, the environmental loads, and the corrosion and aging of the structure, the joints are prone to fatigue cracks which can lead to crack propagation. The fatigue cracks and crack propagation can be investigated by analyzing the stress intensity factor (SIF) of the crack. If the SIF exceeds the fracture toughness of the joint, the crack will propagate. To alleviate this issue and prevent crack propagation, the application of composite reinforcement has been receiving traction in the industry due to its ability to provide in-service maintenance windows, besides its renowned capability to enhance the structural integrity of affected offshore structures. However, the effect of composite reinforcement on the SIF of fatigue-cracked tubular T-joints has been insufficiently explored. Therefore, this study aims to conduct a numerical parametric study on a semi-elliptical cracked tubular T-joint to investigate the effect of crack size, crack location, and composite reinforcement on the SIF under various basic loadings.