Marine Structures 70 (2020) 102688 Available online 8 November 2019 0951-8339/© 2019 Elsevier Ltd. All rights reserved. Uncertainties estimates of hull girder still water loads of bulk and dry cargo ships through Monte Carlo simulations Tomaso Gaggero, Marco Gaiotti, Cesare Mario Rizzo * University of Genova, Polytechnic School, DITEN, Polo Navale, via Montallegro, 1, I-16145, Genova, Italy A R T I C L E INFO Keywords: Hull girder strength Still water loads Loading conditions Uncertainties Monte Carlo simulations ABSTRACT This paper deals with the estimate of uncertainties affecting still water hull girder loads of bulk and dry cargo ships. In strength assessment of ships, two main categories of acting loads are considered: still water loads and wave induced ones. While the latter are generally defned bearing in mind their stochastic nature, this is not the case for still water loads, which are basically deterministically considered. The underlying assumption is that there is an overall control of the operational profle during the service of a ship. However, this is not the case in actual fact, especially for general dry cargo ships and bulk carriers, since the loading/unloading process cannot be fully controlled by the crew, often resulting into loading conditions rather different from those planned by the designer. Based on an earlier work, where loading conditions of the above-mentioned ship types were statistically analyzed, in the present paper Monte Carlo simulations are used to estimate the uncertainties affecting the hull girder still water loads of ships in service, showing that their allowable values can be exceeded due to inaccuracies in ship and cargo management. 1. Introduction As a matter of fact, hull girder still water loads are to be provided by the designer and summed up to rule wave-induced loads in order to assess the hull girder strength according to classifcation societies rules. It is common understanding that hull girder still water loads are well known and their estimates are only marginally touched upon by uncertainties. In fact, relevant partial safety factors are generally set to unity, as e.g. γ s ¼ 1.00 in RINA rules for the classifcation of ships [1], meaning that no uncertainties are considered affecting such loading parameter and they are considered as deterministic variables. Instead, larger uncertainties are taken into account when assessing wave loads, and partial safety factors are applied accordingly. However, reality could be somewhat different, especially for a few ship types such as dry bulk carriers or general cargo ships. Indeed, the actual scenario is much more complex than that described in rules, because of the complexity of cargo loading and unloading operations. It is of interest to assess such uncertainties in order to obtain adequate knowledge of the phenomena and to reduce the gap between design assessments and reality. Hence, contributing to improve reliability and effectiveness of shipping. While loading conditions of all ships are described in their loading manuals, duly approved by the Flag Administrations or by classifcation societies on their behalf, the actual longitudinal weight distribution of a ship at departure and at arrival of a voyage leg is * Corresponding author. E-mail addresses: tomaso.gaggero@unige.it (T. Gaggero), marco.gaiotti@unige.it (M. Gaiotti), cesare.rizzo@unige.it (C.M. Rizzo). Contents lists available at ScienceDirect Marine Structures journal homepage: http://www.elsevier.com/locate/marstruc https://doi.org/10.1016/j.marstruc.2019.102688 Received 9 January 2019; Received in revised form 6 August 2019; Accepted 26 October 2019