Time-varying ultimate strength of aging tanker deck plate considering corrosion effect Jinting Guo a, b, * , Ge Wang a , Lyuben Ivanov a , Anastassios N. Perakis b a American Bureau of Shipping, 16855 Northchase Drive, Houston, TX 77060, USA b Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, MI 48109, USA article info Article history: Received 16 November 2007 Received in revised form 21 February 2008 Accepted 7 March 2008 Available online XXXX Keywords: Corrosion wastage Semi-probabilistic approach Ultimate strength Reliability-based approach Time-varying reliability Risk-based inspection Aging tankers abstract This paper presents a semi-probabilistic approach to assess the time-varying ultimate strength of aging tanker’s deck plate con- sidering corrosion wastage. The procedure includes (1) defining the limit state function of deck plate failure, (2) determining the time-varying probability density function of corrosion wastage and values for selected severity levels of corrosion, (3) calculating the time-varying ultimate strength of deck plates corresponding to the selected levels of corrosion wastage, (4) determining the time-varying maximum nominal stress, (5) calculating when the deck plate reaches the ultimate strength limit state, and (6) deter- mining the inspection intervals based on the risk of ultimate strength failure. A nonlinear corrosion model was proposed for deriving the time-varying probability density function of deck plates’ corrosion wastage. The probability density function was determined based on a statistical analysis of the American Bureau of Shipping (ABS) corrosion wastage database [Wang G, Spencer J, Sun HH. Assessment of Corrosion Risks to Aging Oil Tankers In: 22nd International Conference on Offshore Mechanics and Arctic Engineering, Cancun, Mexico, 8–13 June 2002]. To simplify the calculations of ultimate strength, a semi-probabilistic model was adopted. Three levels of corrosion severity were considered, and the corresponding values of corrosion wastage were used instead of the probability density function. The increasing nominal stresses as ships age were also taken into account considering the loss of global hull girder section modulus. The loads of still- water-induced and wave-induced bending moments were treated * Corresponding author. American Bureau of Shipping, 16855 Northchase Drive, Houston, TX 77060, USA. Tel.: þ1 281 877 6588; fax: þ1 281 877 6796. E-mail addresses: jtguo@umich.edu, jiguo@eagle.org (J. Guo). Contents lists available at ScienceDirect Marine Structures journal homepage: www.elsevier.com/locate/ marstruc ARTICLE IN PRESS 0951-8339/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.marstruc.2008.03.002 Marine Structures xxx (2008) 1–18 Please cite this article in press as: Guo J et al., Time-varying ultimate strength of aging tanker deck plate considering corrosion effect, Marine Structures (2008), doi:10.1016/j.marstruc.2008.03.002