THE EFFECTS OF STRESS REDISTRIBUTION DUE TO MEMBER FAILURE ON STRUCTURAL RELIABILITY OF OFFSHORE STEEL JACKETS

摘要

Current practice in providing structural integrity assurance of North Sea Steel Jacket structures relies upon periodic inspection of the sub-structures, with FMD being the preferred method of inspection. The time period between inspections, when employing FMD is dependent upon the structure's level of redundancy. However, little, if any, consideration is given to the effect a failed member has on the stress distribution within the structure and the probability of a second member failing. A study has been completed that investigated the impact of stress redistribution following failure of a member. The study has considered the impact this has on fatigue lives of adjacent members/joints, and ultimately the impact on structural reliability. The findings from this study suggest that for the type of structures considered, the justification for a given inspection schedule should take due account of the impact of stress redistribution and the possibility that a structure might experience a second member failure during an inspection interval.