Ships and Offshore Structures
Vol.1,  Issue 3, pp.235-247


Idealized structural unit method and its application to progressive hull girder collapse analysis of ships


J.K.Paik, J.K.Seo and D.M.Kim


Abstract:
Idealized structural unit method (ISUM) is now well recognized as one of the most efficient methods to analyze nonlinear behavior of large-sized structures under extreme or even accidental actions. This paper presents some techniques of ISUM modeling and surveys the literature on the ultimate limit state assessment of ship structures using ISUM. Theoretical formulations of ISUM elements for the progressive hull girder collapse analysis of ships that were implemented into ALPS/HULL computer code are outlined. Some benchmark studies are made by a comparison with physical test data and ALPS/HULL analyses on a frigate ship hull model under sagging moment tested by UK royal Navy and on two double-skin tanker hull models under sagging or hogging moments tested by US Navy. Some ALPS/HULL application examples to progressive collapse analysis of a double-skin shuttle tanker hull under combined vertical and horizontal bending moments are then demonstrated. It is concluded that ISUM is very useful for the progressive hull girder collapse analysis of ships because it provides very accurate results while the computing time is very short.