Elsevier

Ocean Engineering

Volume 63, 1 May 2013, Pages 112-121
Ocean Engineering

Lateral pressure effects on the progressive hull collapse behaviour of a Suezmax-class tanker under vertical bending moments

https://doi.org/10.1016/j.oceaneng.2012.12.040Get rights and content

Abstract

This paper presents the results of an investigation of the effect of lateral pressure on the progressive hull collapse behaviour of a double-hull oil tanker subject to vertical bending moments in both the sagging and hogging conditions. As an illustrative example, a Suezmax-class double-hull oil tanker designed by the Common Structural Rules (CSR) method is considered. The ANSYS nonlinear finite element method (NLFEM) is employed for the progressive hull collapse analysis. The effects of lateral pressure – static (anchored condition) and dynamic (operating condition) – are investigated in both the full-load and ballast conditions. To check the accuracy of ultimate hull girder strength analysis methods, Dow's test hull is also applied together with Suezmax class oil tanker under conditions of vertical bending moment but without lateral pressure loads. In this regards, the NLFEM method is compared with ALPS/HULL intelligent supersize finite element method (ISFEM) programs and International Association of Classification Societies (IACS) CSR method, which applies the idealized structural unit method (ISUM) (also called the Smith method). The important insights developed from the present study are documented.

Highlights

► Analysis results obtained with the three methods are in reasonably good agreement with one another. ► Applied model (1 sliced hull) is not relevant when combined hull girder loads are applied. ► The effect of lateral pressure loads on progressive hull collapse behaviour is relatively small.

Introduction

It is well-recognised that limit states-based methods are superior to allowable working stress-based methods for the structural design and strength assessment of ships and offshore structures. International organisations such as the International Association of Classification Societies (IACS), International Maritime Organization (IMO) and International Organization for Standardization (ISO) have developed new international rules and guidelines for structural design and strength assessment by applying first principles-based approaches, limit states-based approaches and risk-based approaches (IACS, 2006a, IACS, 2006b, IMO, 2010, ISO, 2007).

Since early 2006, Common Structural Rules (CSR) are specified by IACS for double-hull oil tankers (IACS, 2006a) and bulk carriers (IACS, 2006b), which make more extensive use of the ultimate strength method than do the pre-CSR methods in terms of the structural scantling. Abovementioned CSR suggested new design rules based on Ultimate Limit State (ULS) to improve the structural safety in both double-hull oil tankers and bulk carriers. However, there is little research in connection with a lateral pressure effect in terms of ultimate hull girder strength behaviour. On the other hand, CSR has only specified the specific procedures for analysing the ultimate vertical bending moment of double-hull oil tanker structures. Actually, the effect of lateral pressure on the ultimate hull girder strength is not taken into account in the CSR procedures. Based on the various research results from other researchers (Paik and Thayamballi, 2003; Paik et al., 2012a,b), it is also recognised that the effect of lateral pressure on plate ultimate strength cannot be neglected for analysis purpose.

Therefore based on that recognition, it is essential to investigate the effect of lateral pressure on the ultimate hull girder strengths. In this regards, this paper presents the investigation outcomes of the progressive hull collapse behaviour of a Suezmax-class double-hull oil tanker subject to vertical bending moments, with a focus on the effect of lateral pressure loads. The two types of lateral pressure effects are mainly considered; static pressure and static+dynamic pressure.

Section snippets

Methods applied to the progressive hull collapse analysis

Three methods were employed to analyse the progressive hull collapse behaviour of the object ship, namely, the ANSYS (2012) nonlinear finite element method (NLFEM), the ALPS/HULL (2012) intelligent supersize finite element method (ISFEM) and the IACS CSR method using the idealized structural unit method (ISUM) (also called the Smith method) (IACS, 2006a, IACS, 2006b).

To validate the three methods, Paik et al. (2013) were also employed to analyse progressive hull collapse in the face of vertical

Object ship: Suezmax-class double-hull oil tanker

The Suezmax-class double-hull tanker considered herein was designed by the CSR method. Its principal dimensions are given in Table 1.

Fig. 14 shows a schematic of the mid-ship section, together with the ship's deck and bottom panel scantlings, for comparison with a pre-CSR design (Paik et al., 2009). Table 2 presents the hull cross-sectional data of the object ship.

The bracketed digits indicate the net scantlings, excluding the corrosion margin values (unit: mm). T=tee-type stiffener, and

Progressive hull collapse analysis with vertical bending moments

Fig. 10 shows the vertical bending moments and bending curvature curves of the Dow test hull model in the sagging condition obtained using the three aforementioned methods. The solutions of two analytical methods, namely, the simple-beam theory method and the presumed stress distribution-based method, are also compared. It can be seen that the ANSYS finite element analysis overestimates the ultimate hull girder strength relative to the test results, whereas both the ALPS/HULL and CSR method

Progressive hull collapse analysis with vertical bending moments and lateral pressure

To investigate the effect of lateral pressure loads, two typical loading conditions, namely, the full-load and ballast conditions, were considered and also two types of ship condition such as anchored (static lateral pressure) and operating conditions (static+dynamic lateral pressure) were taken into account based on CSR (IACS, 2006a) as shown in Figs. 16 and 17. The progressive hull collapse analysis taking into account the effect of lateral pressure was performed only with the ANSYS NLFEM.

Conclusions

The aim of the study reported herein was to investigate the effect of lateral pressure loads on the progressive collapse behaviour of a hull subject to vertical bending moments in the full-load and ballast conditions. The ANSYS nonlinear finite element method (NLFEM) was mainly applied to perform the progressive hull collapse analysis taking into account the effect of lateral pressure loads. The IACS CSR method and ALPS/HULL intelligent supersize finite element method (ISFEM) were also employed

Acknowledgements

The work reported herein was undertaken at The Ship and Offshore Research Institute (Lloyd's Register Foundation Research Centre of Excellence at Pusan National University, Korea). Lloyd's Register Foundation supports the advancement of engineering-related education, and funds research and development that enhances safety of life at sea, on land and in the air. The research was supported by the Basic Science Research Programe through the National Research Foundation of Korea (NRF) and funded by

References (18)

  • ALPS/HULL, 2012. A Computer Program for Progressive Collapse Analysis of Ship Hulls. Advanced Technology Center, DRS C3...
  • ANSYS

    User's Manual (version 14.0)

    (2012)
  • Dow, R.S., 1991. Testing and analysis of a 1/3-scale welded steel frigate model, 2nd International Conference on...
  • O.F. Hughes et al.

    Ship Structural Analysis and Design

    (2010)
  • IACS, 2006a. Common Structural Rules for Double Hull Oil Tankers. International Association of Classification...
  • IACS, 2006b. Common Structural Rules for Bulk Carriers. International Association of Classification Societies, London,...
  • IMO, 2012. Harmonised Common Structural Rules (HCSR) for Oil Tankers and Bulk Carriers, Submitted by the International...
  • IMO

    Goal-based Standards

    (2010)
  • ISO, 2007. International Standards ISO 18072-1. Ships and Marine Technology – Ship structures – Part 1: General...
There are more references available in the full text version of this article.

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