Human and Organizational Factors in Reliability and Design of ‘Minimum’ Offshore Structures

‘Minimum’ offshore structures represent a class of structures that have been optimized to deliver minimum Capital Expenditures. This paper summarizes a part of the work done for a Joint Industry –Government sponsored project to study the reliability characteristics of minimum offshore structures for the North Sea [1 ]. Three minimum structures were compared with a conventional 4-leg jacket structure. These structures all were designed for specific conditions at a site in the North Sea using current design and engineering criteria appropriate for these structures. The reliability characteristics of these structures were evaluated for in-place operating conditions considering strength — extreme storm conditions, fatigue conditions, and accidental – boat collision conditions. This paper addresses and summarizes the reliability characteristics of these structures evaluated for defect and damage states due to Human and Organizational Factors (HOF) that developed during design, construction, maintenance, and operation. The HOF based defect and damage states were based on information gathered from designers, builders, and owner – operators of similar structures and from databases that contain information on HOF based defects and damage in offshore structures. An advanced reliability formulation was developed and applied that allowed integration of the intrinsic (natural) and extrinsic (HOF) hazards. This paper summarizes the advanced reliability formulation that was applied, the processes used to define and evaluate the HOF defect and damage scenarios, the results from evaluations of the scenarios with conventional and advanced QA/QC (Quality Assurance/Quality Control) processes, and the results of platform structure system analyses with and without recognition of the HOF effects.