Reliability-based load and resistance factor design (LRFD) guidelines for stiffened panels and grillages of ship structures

Stiffened panels and grillages are very important components in ship and offshore structures, and therefore they should be designed for a set of failure modes that govern their strength. They form the backbone of most ship's structure, and they are by far the most commonly used element in a ship. They can be found in bottom structures, decks, side shell, and superstructures. To evaluate the strength of a stiffened panels or grillages, it is necessary to review various strength predicting models and to study their, biases, applicability, and limitations for different loading conditions acting on the element. In this paper, strength limit states for various failure modes of ship panels are presented. For each limit state, commonly used strength models were collected from many sources for evaluating their limitations and applicability and to study their biases and uncertainties. Wherever possible, the different types of biases resulting from these models were computed. The bias and uncertainty analyses for these strength models are needed for the development of load and resistance factor design (LRFD) guidelines for stiffened panels and grillages of ship structures. The uncertainty and biases of these models were assessed and evaluated by comparing their predictions with ones that are more accurate or real values. The objective of this paper is to develop load and resistance factor design (LRFD) for stiffened panels and grillages of ship structures. Monte Carlo simulation was used to assess the biases and uncertainties for these models. Recommendations for the use of the models and their biases in LRFD development are provided. The first-order reliability method (FORM) was used to develop the partial safety factors (PSFs) for selected limit states.