Uncertainty Analysis of Load Combination Factors for Global Longitudinal Bending Moments of Double-hull Tankers

Author: Teixeira Angelo P.   Guedes Soares C.   Chen Nian-Zhong   Wang Ge  

Publisher: Society of Naval Architects and Marine Engineers (SNAME)

ISSN: 0022-4502

Source: Journal of Ship Research, Vol.57, Iss.1, 2013-03, pp. : 42-58

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Abstract

The present article aims at assessing the probabilistic characteristics of the load combination factors for global longitudinal bending moments of double-hull tankers. The calculations are performed based on a sample of oil tankers representative of the range of application of the Association of Classification Societies' (IACS)-Common Structural Rules (CSR) design rules. The article starts by reviewing the probabilistic models that have been proposed to model stillwater and wave-induced loads and their characteristic extreme values. Different load combination methods are also reviewed including an analytical method that provides the combined characteristic value of stillwater and wave-induced bending moments based on the Poisson assumption for upcrossing events and using the first-order reliability method in combination with the point-crossing method. The predictions of the different load combination methods are assessed on the basis of a sample of five oil tankers adopted during the IACS-CSR design rules development process. A parametric and an uncertainty propagation study are then performed to identify the range of variation and the probabilistic models of the load combination factors that are applicable to double-hull tankers.