<p>This study investigates the ultimate strength and deformation behaviour of tubular T-joints, often used in offshore structures, reinforced with collar plates and external ring stiffeners. The nine T-joints for three different β values, 0.25, 0.5 and 0.75 and with two different strengthening techniques (1) external ring stiffeners and (2) collar plate, were studied under brace compression. The effects of key parameters such as β (brace-to-chord diameter ratio), γ (chord slenderness ratio), and stiffener configurations on joint performance were analysed. Finite Element Analysis (FEA) results demonstrated close agreement with experimental data, showing a variation of less than 4%. Reinforcements significantly enhanced load-carrying capacity, with ring stiffeners increasing strength by up to 36% and collar plates by 39%. The optimal parameters, including β = 0.75 and γ = 20, improved stiffness and minimised deformation. Finite Element Analysis (FEA), and EC3 code predictions were compared, demonstrating close agreement with R² values of 0.9726 and 0.9577 for collar plate and ring-stiffened joints, respectively. These findings highlight the effectiveness of reinforcements in improving joint strength and structural integrity of offshore platform.</p>