In-place and lift analysis of an offshore module: Comparative study

Abstract

Design of offshore structures involves a variety of subjects including effects of harsh environmental conditions, variable loading patterns at each stage of the work and different accident scenarios e.g. explosions and collision.

A structural engineer need to have sufficient knowledge and experience and pay due attention to each and every detail along with the general design considerations in order to overcome all design challenges and fulfill the requirements set up for structures.

The main objective of this thesis is to gain an overall understanding of diverse issues related to design and analyses of the offshore structures through a redesign and comparison work. Results from this global structural reanalysis can be used to assess and ensure the safety level of the existing structure within the assumed conditions.

Analysis and design evaluation of an existing topside module have also been the pretext for presenting some of the general design consideration within this thesis. Comparison between the old existing practice and the current practice will be made wherever possible.

This master’s thesis includes the following topics: • Study and implementation of regulations and rules for offshore construction. • In-place and lift analysis of an existing offshore module for the relevant actions in order to verify structural capacity and ensure safety of the structure. • Learning the analysis software SESAM GeniE and using it as the analysis tool. • Detail modelling of joints using plate elements and connecting the joint to the main analysis model to find the maximum stress values. • Padeye model made with plate elements for analysis of stress distribution when subjected to the maximum sling load.

The analyses done for in-place condition and lifting operation of the module verify that all engineering work complies with the given specifications, maintains the structural integrity and level of quality needed to ensure safe operation of the installation.