Structural Safety Assessment of a 15,000TEU Container Ship Considering an Increased Scallop Radius

Abstract

The hull structure is assembled by welding plates and stiffeners, and welding efficiency plays a critical role in ship production. Scallops are widely incorporated into hull structures to enhance welding efficiency; however, the resulting reductions in cross-sectional area and section modulus must not compromise structural integrity. In this study, a finite element structural analysis model based on the midship section of a container vessel was developed to quantitatively evaluate the structural response as a function of scallop radius. Eight load cases were analyzed with particular emphasis on stress concentration phenomena at scallop regions. At the scallop edge, both shear stress and von Mises stress exhibited a consistent increasing trend with increasing scallop radius; nevertheless, all stress values remained within the allowable design limits, even at a scallop radius of 250mm. Stress distributions were additionally examined at the girder and inner bottom, where scallops introduce geometric discontinuities. A transition in the dominant stress concentration mode was identified at a specific scallop radius threshold. The local stresses in both the girder and inner bottom were found to satisfy the prescribed design criteria, suggesting that the current conservative scallop radius design standards may have room for relaxation.