A design—decision support framework for evaluation of design options/proposals using a composite structure methodology based on the approximate reasoning approach and the evidential reasoning method

Abstract

Abstract

With the cost of construction, operation and maintenance estimates in the multi-millions of pounds, the offshore industry is seeking ways of reducing both the time and money spent in providing the high-quality offshore structures needed to support oil and gas extraction and production. Most real world design evaluation and risk-based decision support combine quantitative and qualitative (linguistic) variables. Decision making based on conventional mathematics that combines qualitative and quantitative concepts always exhibits difficulty in the modelling of actual problems. The successful selection process for choosing a design/procurement proposal is based on a high degree of technical integrity, safety levels and low costs in construction, corrective measures, maintenance, operation, inspection, as well as preventive measures. However, the objectives of maximizing the degree of technical performance, maximizing the safety levels and minimizing the costs incurred are usually in conflict, and the evaluation of the technical performance, safety and costs is always associated with uncertainty, especially for a novel system at the initial concept design stage. In this paper, a design—decision support framework using a composite structure methodology grounded in an approximate reasoning approach and an evidential reasoning method is suggested for design evaluation of offshore engineering products at the initial stages. It is a multiple attribute decision-making (MADM) or multiple-criteria decision-making framework, which provides a juxtaposition of cost, safety, and technical performance and other objectives of a system during evaluation to assist decision makers in selecting the winning design/procurement proposal that best satisfies the requirement in hand. It has also been shown that the formal decision-making techniques such as the Analytical Hierarchy Process (AHP) and the Delphi method can be incorporated with the proposed framework in carrying out design support evaluation. An illustrative example is used to demonstrate the application of the proposed framework.