Detailed Finite Element Analysis of 180 M Deck Cargo / Launch Barge B42

Abstract

In this study, a detailed finite element analysis methodology of a 180 m deck cargo/launch barge B42 for 32,000 MT topside load is described and results are presented. Using Finite Element Method (FEM) for large welded steel structures such as a deck cargo/launch barge has been quite challenging in past because the engineer had to observe the balance between solution accuracy and numerical efficiency. However, recent improvements in solver algorithms in FEM packages and increasing core processor numbers in computers enable engineers to include a lot more details to their FE model so that accurate stiffness and mass of the structure can be simulated. In this study, the entire barge is modelled in ANSYS Software using shell elements including longitudinal beams, stiffeners, flanges, base plates, skid tracks and outriggers. Two most critical load cases were analyzed; the first is the maximum hogging condition which occurs in the topside loadout sequence where the topside is entirely on barge deck towards stern. The second load being the maximum sagging case where the topside is at the final location on the deck of barge for transportation. Results of the detailed FE analysis confirmed the structural integrity of the barge showing all the stresses and displacements are below allowable limits for all load cases. Two main advantages were observed through detailed modelling of the entire barge. Firstly, a faster preprocessing time is as compared to shell-beam models. Secondly, increasing the mesh density in critical locations in global FE model will be equivalent to a sub-model in this case. Thus, eliminating the need for analyzing any detail separately.