RELIABILITY BASED DESIGN OF STIFFENED PANELS IN PRODUCTION SHIPS UNDER COMBINED BIAXIAL AND LATERAL LOADING

Design of the longitudinally stiffened panels of a typical North Sea production ship is addressed. The failure mode considered is collapse of stiffened bottom and deck panels resulting from combined biaxial and lateral loads. The longitudinal compressive stresses stem from hull-girder still water and wave bending moments. The transverse compressive stresses and lateral bending stresses arise from local static and dynamic pressures. The limit state function is established under the load interaction using the beam-column approach, for which the model uncertainty is estimated based on nonlinear ultimate strength analysis. Probabilistic models for the basic strength and load variables are presented accounting for stochastic load combination. Safety levels implied in a buckling design code are estimated for both hogging and sagging conditions. More consistent safety levels are obtained through calibration of rational load coefficients.