RESIDUAL HULL GIRDER ULTIMATE STRENGTH OF DOUBLE HULL OIL TANKERS

Within the scope of the presented work a hull girder ultimate strength analyses of the double hull oil tanker structures damaged by the collision or grounding is performed. An incremental-iterative progressive collapse analysis method prescribed by the forthcoming IACS Harmonized Common Structural Rules (H-CSR) is used for determination of the ultimate vertical bending moment and collapse sequence of the considered structures. Three characteristic variants of the oil tanker main frame cross sections of a different geometry and size (Aframax, Suezmax and VLCC) are considered. The position of a ship's side and/or bottom damage is defined in accordance with the IACS H-CSR. Proposed analytical formulations of the relationship between reduction of the hull girder ultimate vertical bending moment (with respect to the undamaged state) and damage size are based on the results of a systematic variation of a ship's side or bottom damage size. Finally, comparison of the collapse sequences determined for the undamaged and damaged state in upright position (defined by IACS H-CSR) of the considered structure of the Aframax ship example is performed.