Misalignment effect on the ultimate strength of welded stiffened panels under uniaxial compression

Abstract

Longitudinal stiffener misalignment (LSM) is inevitable in the manufacturing process of stiffened hull panels, affecting the geometric appearance and bearing capacity. However, the knowledge of the effect of LSM on the ultimate strength of stiffened panels is limited. In this paper, continuous numerical simulations are first conducted regarding forced alignment, welding process and ultimate strength analysis by using the nonlinear finite element method. A simplified model is then derived considering LSM and initial deflection based on a comparative study of the ultimate strength and collapse patterns. Influences of various combinations of LSM and initial deflection on the strength characteristics and failure behaviors are documented and discussed. According to the parametric analysis, it is found that the LSM imperfection decreases the ultimate strength, but the degree of reduction depends on the shape and amplitude of the panel initial deflection. The maximum reduction rate is 8.71% occurring in the case where the deflection shape with slight amplitude is symmetric. On the basis of 120 numerical results, an empirical formula is proposed for predicting the residual strength as a function of the dimensionless misalignment degree together with panel and column slenderness.