Jerolim Andrić

Design synthesis of complex ship structures

The paper presents the principal steps in the definition of a practical design model for multi-criteria synthesis of complex thin-walled ship structures in concept and preliminary design. It elaborates the general requirements on the design procedure, balanced and applicable combinations of design models and a practical example of the basic analysis models/IT modules within the MAESTRO/OCTOPUS design support system. System identification from the multi-stakeholder perspectives of owner and society, and the formulation and solution to the dimensionally large-scale structural designs are presented as a step towards the practical implementation of multi-criteria decision-making in ship design practice since only a joint effort could lead to the satisfaction of all stakeholders in todays challenging ship-building industry. The practical structural design procedure/methodology, capable of embedding multiple design quality criteria, is demonstrated using a benchmark case study on the innovative RoPax ship.

Structural reliability assessment of container ship at the time of accident

Hull girder reliability assessment of the MSC Napoli at the time of accident is presented. Loads considered in the study are still water bending moments, vertical wave bending moments and whipping bending moments, while structural capacity is represented by the hull girder ultimate strength. Load combination between wave and whipping bending moments is considered. The probability of failure is calculated using a first-order reliability method. Sensitivity study is performed in order to investigate influence of the pertinent random variables. The uncertainty model of the basic random variables involved is consistent with the recent proposal by the International Maritime Organization, thus enabling direct comparison of the obtained results with reliability levels proposed by International Maritime Organization.

Structural design and analysis of a large ‘open type’ livestock carrier

ABSTRACT ‘Open type’ livestock carriers are multi-deck ships characterised by the large openings in the superstructure side shell and with the absence of transverse and longitudinal bulkheads in the superstructure. The height of the superstructure is approximately equal to the height of the lower hull and the influence of hull-superstructure interaction on longitudinal strength is very important and should be taken into consideration during determination of the structural scantlings in very early design phase. This kind of ship topology generates two main structural challenges in: (1) longitudinal strength due to partially effective participation of the superstructure in global hull girder bending and (2) transverse/racking strength due to absence of transverse bulkheads in the superstructure. Since relatively small number of vessels of this kind currently exists, their specific structural aspects are poorly documented in the literature. This paper discusses and highlights basic challenges in the structural design and analysis of the ‘open type’ livestock carriers, using ULJANIK shipyard Newbuilding 526 as an example.

Optimization procedure for liquid natural gas carrier structural design

The purpose of this article is to present the design procedure and the main results of its validation through the liquid natural gas carrier structural optimization. The work has been carried out through the EU FP6 project IMPROVE. The objective of the developed optimization process was to distribute the material more effectively in order to reduce weight/cost and to improve the structural safety in the allocated time frame. A coarse mesh finite element method model (three holds) has been developed, using MAESTRO software. Strength calculation has been carried out according to the Bureau Veritas Rules for direct calculation. Sensitivity analysis has been performed to investigate the influence of web frame spacing, longitudinal stiffener spacing and material type on the specified design objectives. Design procedure applied for the structural optimization of the liquid natural gas structure (one cargo hold) resulted in mass decrease of about 424 t (after standardization of scantlings), or 10.8%; the cost of the structure was reduced by about 5%; structural safety was increased and vertical center of gravity was slightly reduced by about 20 cm compared to the prototype structure.