Ultimate shear strength of intact and cracked stiffened panels

• Crack is considered as a parameter affecting the strength of stiffened panels and the ultimate shear strength characteristics of intact and cracked stiffened panels are investigated based on parametric analysis.
• Three types of cracks are considered, namely vertical crack, horizontal crack and angular crack.
• The formula for the ultimate shear strength of cracked stiffened panels is derived, which can be valuable for life assessment of aged ship structures.

The present paper focuses on the ultimate shear strength analysis of intact and cracked stiffened panels. Several potential parameters influencing the ultimate shear strength of intact panels are discussed, including the patterns and amplitudes of initial deflection, the slenderness and aspect ratios of the plates, and the boundary conditions defined by the torsional stiffness of support members. An empirical formula for the ultimate shear strength of intact stiffened panels is proposed based on parametric nonlinear finite element analyses in ANSYS. Furthermore, the ultimate shear strength characteristics of cracked stiffened panels are investigated in LS-DYNA with the implicit method. Three types of cracks are considered, namely vertical crack, horizontal crack and angular crack. A simplified method is put forward to calculate the equivalent crack length. And the formula for the ultimate shear strength of cracked stiffened panels is derived on the basis of the formula for intact stiffened panels.