<p>This paper presents an engineering critically assessments of a floating offshore platform structure based on time domain structural response analysis.</p><p>Demand continues to grow in the offshore industry to attain value from captured operational data for a number of purposes including the reduction of uncertainties in structural integrity assessments during design and over the operational lifetime of floating offshore platforms. Recent advances in time domain structural analysis technology demonstrate substantially more accurate assessment of non-linear platform loadings and response with enhanced computational efficiency [OMAE2019-96139, OMAE2020-18314]. The current S-N approach for fatigue design and integrity assessments calculates a fatigue damage factor that does not address how loading occurs over time [ABS Guide for Fatigue Assessment of Offshore Structures, DNVGL-RP-C203]. For the present study engineering criticality assessments (ECAs) based on fracture mechanics theory [BS 7910] is applied utilizing time-domain loading information theory. The ECA returns the smallest initial flaws that can grow to a critical size during a design lifetime, which can serve as an indicator of acceptability during design, a technical basis for in-service inspection intervals and facilitates asset integrity and life extension assessments. Critical initial flaws are calculated using the Paris Law [BS7910] and cumulative fatigue crack growth in two ways: 1) annualized fatigue loading histogram representative of the entire service life and 2) an array of fatigue loading histograms each representing a 3-hour timespan through the design lifetime. The fracture limit state is applied to check for unstable failure as an option to both. The results are compared with those from S-N fatigue analyses and recommendations for using ECAs in structural analyses are provided.</p>

Engineering Criticality Assessments of Floating Offshore Platforms Based on Time Domain Structural Response Analysis

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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