Progressive Collapse Behaviour of VLCC under Longitudinal Bending

Abstract

The aim of this study is to analyse the ultimate strength of VLCC subjected to longitudinal bending moments under hogging and sagging conditions. One-frame space in the mid-ship section of VLCC is taken to be assessed. The Nonlinear Finite-Element Analysis method (NLFEA) is adopted in this study. The boundary and loading conditions are applied on both sides of the ship cross section. The Multi Point Constraint (MPC) is imposed to the cross section based on the neutral axis references. The element type is SHELL 181 is used on the model. The meshing size is 500 mm, and the arc length method is applied to solved the load and shortening curve. The initial imperfection, cracks and welding residual stress are ignored. The result obtained by NLFEA method for ultimate strength in hogging and sagging are 10,83x1012 Nmm and -10,34x1012 Nmm, respectively. It is shown that the ultimate strength obtained by NLFEA is larger than Smith's method, and the ratios of the ultimate strength comparison are 7,71% and 11,27% for hogging and sagging conditions, respectively.