Consequences of the Improved Wave Statistics on a Hull Girder Reliability of Double Hull Oil Tankers

• Published in: Journal of marine science and engineering 2024-04, Vol.12 (4), p.642
• Main Authors: Parunov, Joško, Mikulić, Antonio, Ćorak, Maro
• Format: Article
• Language: English
• Subjects: Bending moments; Classification; Committees; Comparative analysis; Computation; Container ships; Deformation; Double hulls; Energy consumption; Failure; hull girder; Load; Loads (forces); Mathematical analysis; Oil; oil tanker; Oil tankers; Oils & fats; Probability; Probability distribution; Random variables; Reliability; Reliability analysis; Safety; Safety factors; Scatter diagrams; Scattering; Ship hulls; Ship speed; Statistical analysis; Statistics; Structural reliability; Tanker ships; Tankers; ultimate bending capacity; vertical wave bending moment; Wave energy; Wave spectra; Wave statistics
• ISSN: 2077-1312; 2077-1312
• DOI: 10.3390/jmse12040642

This paper investigates the change in hull girder failure probabilities and partial safety factors caused by the implementation of the new procedure for direct computation of wave loads recommended by the International Association of Classification Societies (IACS). Differences between new and previous procedures are primarily related to the different associated scatter diagrams, and secondarily due to the assumptions on wave spectrum, wave energy spreading, and ship speed. This study performs a comparative structural reliability analysis of the global longitudinal bending of five oil tankers of different sizes between two procedures for wave load computation. Firstly, failure probabilities are compared, and secondly, modified partial safety factors are proposed, resulting in similar failure probabilities according to two separate procedures. It is found that implementation of the new revision of the IACS procedure for direct computation of wave loads results in a reduction of the minimum required ultimate vertical bending capacity of a ship hull by 10%. In addition to the novel investigation of the safety of oil tankers using a revised wave scatter diagram, this study offers a new rapid method for calculation of extreme vertical wave bending moments based on the regression of the parameters of the Weibull function, used for the long-term probability distribution of wave-induced loads.