Probabilistic Damage Stability of Ro-Ro Ships

International Journal of Technology, 2019

One of the most important criteria in ship design is strength. When a ship is under external loads such as waves, buoyancy or pressure, its internal reaction must resists those external loads. In this regard, external loads are retained by the hull girder, whose cross section is composed of plates and stiffeners, which have a significant influence on ultimate strength, especially in the longitudinal direction. Therefore, this strength must be assessed and evaluated for the ship structure and functional requirements. In this study, local elements of the ship cross section, such as plates and stiffeners, are analyzed, including their progressive collapse behavior. The example used for the calculation is a Roll-on/Roll-off (Ro-Ro) ship. The analysis is performed by assuming that the cross section remains plane and a one-frame space is considered. To calculate the ultimate strength of the Ro-Ro ship under hogging and sagging conditions, Smith's method is used and applied to an in-house program. The applied moment is given on the Multi Point Constraint (MPC) as the reference point of the neutral axis position. In this MPC position, a simple support is attached. The calculation of ultimate strength is made under hogging and sagging conditions, and the intact condition is focused on for the simple calculation. Welding residual stress, cracks, corrosion and initial deflection are not taken into account. Application of the FE method is also made to investigate the characteristics of the collapse mode for local elements and global structure, including ultimate strength.

2014

Journal of Marine Science and Technology, 2012

The time dependence of survivability of ROPAX vessels, when sustaining side collision damage in waves, is investigated herein by use of numerical simulations of ship motion and flooding. Conducted research confirms that ROPAX ships characteristically capsize fast, when sustaining damage leading to capsizing. A probabilistic analysis of the survive time after collision damage reveals that even for the most generic damage conditions assumed, the survival time in the case of capsizing remains short, which is characteristic of this type of ship design, disposing the typically large undivided deck to be subject to flooding in higher waves. In a case study, the unconditional survivability in waves, corresponding to survival s-factor of SOLAS regulations, is alternatively assessed with numerical simulations. The estimated survivability proves to be time independent in terms of practical implications. Observed deviations between current SOLAS formulation and simulations, suggest the employment of comprehensive simulation methods when more reliable estimations and assessments of survivability are required.

… on Design for Safety, Sakai-Osaka, 2004

This paper presents results of studies on the harmonization of a new probabilistic regulatory framework with the currently in-force damage stability regulations as well as their anticipated impact on the design of dry cargo and passenger ships. In particular, the scope of the ...

IOP Conference Series: Materials Science and Engineering

Ro-Ro ship has special characteristic for cargo handling because the cargo is transferred in horizontal direction. For example, cars can move by using ramp door which is located in front and/or aft of the ship. In conjunction with this, car passenger and other decks such as top including bottom part need to be investigated for local and global of Ro-Ro ship structure. In the present study, the ultimate strength investigation of Ro-Ro ship is conducted. There are three types of Ro-Ro ships are taken as the ship's subject. The cross section of Ro-Ro is considered in the analysis and it is modelled having plate and stiffened plate. The one-frame is represented in longitudinal direction. The simply supported of boundary condition is applied and the cross section is assumed to be remained plane. The calculation of the ultimate strength using in-house integrated program. The ultimate strength of Ro-Ro ship is investigated under hogging and sagging conditions. The vertical bending moment is imposed to the cross section to obtain the ultimate strength including their progressive collapse. The result obtained by in-house program for three types of Ro-Ro ships are summarized and the collapse behaviour for local and global of the decks to the ultimate strength of Ro-Ro ship are also presented in this study.

Accident Analysis & Prevention, 2013

Damaged ship stability Probabilistic assessment Goal-based design Risk-based design Passenger ship safety a b s t r a c t

Ocean Engineering, 2005

Measurements of global loads acting on a Ro-Ro model have been carried out in regular waves for intact and damaged conditions. The stationary model was tested in different wave heights and wave frequencies for the head, beam and stern quartering seas in order to explore the effect of damage and wave heights on the global loads acting on the model. The analysis of the results indicates that damage has an adverse effect on the structural loading responses of the model depending upon the directionality of the waves and frequency range applied. This effect may cause structural damage on the ship and danger the safety of the ship and passengers on board. q

The new probabilistic damaged stability regulations for dry cargo and passenger ships (SOLAS 2009), which entered into force on January 1, 2009, represent a major step forward in achieving an improved safety standard through the rationalization and harmonization of damaged stability requirements. There are, however, serious concerns regarding the adopted formulation for the calculation of the survival probability of passenger ships and the associated required subdivision indices, particularly for RoPax and large cruise ships. The present paper outlines the objectives, the methodology of work and main results of the EU-funded FP7 project GOALDS (Goal Based Damage Stability, 2009-2012), which aims to address the above shortcomings by formulating a new rational, goal-based regulatory framework, properly accounting for the damage stability properties of passenger ships and the risk to people onboard.

With the aim of analysing the current status and possible future perspectives of research in the field of ship stability, dynamics and safety, this paper deals with an extensive review of the research work presented at the International Conferences on Stability of Ships and Ocean Vehicles (STAB Conferences) and the International Ship Stability Workshops (ISSW) held during the period 2009-2014. The reviewed material is organised in different sections, corresponding to a set of identified main typical focal macro-topics of research. On the basis of the reviewed material, consolidated research topics are highlighted together with emerging topics, and ideas for possible future research and its needs and focus are provided. Discussion is also provided regarding the link between research and educational aspects.

Journal of Marine Science and Engineering

The paper complements an earlier publication by the authors addressing the probability of survival in the IMO framework for damage stability assessment, the s-factor. The focus here is on the probability of occurrence of a certain damage scenario (breach), conditional on its dimensions and location (centre and port or starboard side), the p-factor. Pertinent assumptions and limitations are explained, following its evolution for specific application to passenger ships. Attempts to provide analytical descriptions of the damage breach distributions as tetrahedra shapes positioned along the ship length whilst accounting for changes in ship geometry, structural arrangements, and subdivision for consumption by the wider profession has led to misconceptions and misunderstandings of what exactly the p-factor is in the context of probabilistic damage stability calculations. This is evidenced by the fact that the same original damage breach distributions, derived in Project HARDER, based on l...