A new method for assessing the safety of ships damaged by collisions

ABSTRACT

The longitudinal strength of a ship decreases with the reduction in its bending moment capacity following a collision accident. Therefore, the damaged ship should be able to reach the closest harbour safely without any catastrophic hull girder collapse. This paper aims to develop a method to predict the hull girder residual strength of double-hull oil tankers by considering probabilistic collision damage scenarios. The collision damage index is defined as the reduction ratio of the vertical hull girder moment of inertia, and the residual strength index is (RSI) characterised as the reduction ratio of the hull girder ultimate bending moment. Four different as-built double-hull oil tankers were studied to demonstrate the proposed method and to formulate the collision damage index. The relationships between the residual strength index and the collision damage index are identified in the form of diagrams. The produced diagrams and regressions represent a first-cut assessment of a ship's safety immediately after taking collision damage.

KEYWORDS:

• Double-hull oil tankers
• probabilistic collision damages
• intelligent super-size finite element method
• residual longitudinal strength
• collision damage index

Acknowledgments

The present study was undertaken at the Korea Ship and Offshore Research Institute at Pusan National University which has been a Lloyd's Register Foundation Research Centre of Excellence since 2008. Lloyd's Register Foundation (LRF), a UK registered charity and sole shareholder of Lloyd's Register Group Ltd, invests in science, engineering and technology for public benefit, worldwide.

Disclosure statement

No potential conflict of interest was reported by the authors.