Welding residual stress of curved plate: Development of empirical formula for predicting ultimate compressive strength

This study presents an empirical formula for predicting the ultimate compressive strength of curved plates incorporating welding-induced defects, with the objective of enhancing structural design for Ocean Mobility applications. The proposed formula uniquely considers both initial deflection and welding residual stress, two major sources of imperfection. It introduces the plate slenderness ratio (β) and the flank angle (θ, in radians) as internal variables. It enables the prediction of ultimate strength across eight representative scenarios, defined by combinations of welding direction, loading condition, initial deflection level, and residual stress distribution. The results indicate that welding residual stress can reduce the ultimate strength by up to 10 %, and the proposed formula demonstrates high accuracy with an average deviation within 0.1 % from FEM results. This research improves existing design equations by systematically incorporating the effects of welding defects, and the proposed formula may serve as a reliable tool for accurate ultimate strength assessment in the structural design of welded curved plates.