Multidimensional Gaidai reliability prognostics for flexible riser in the Gulf of Aqaba,accounting for dynamic memory effects

Abstract

Marine risers are widely utilized within the offshore industry; they are often being exposed to extreme in situ structural (or environmental) dynamic loads. Robust characteristic/design values assessment for marine riser dynamics, under nonstationary ocean current actions, being a nontrivial engineering task. Vortex-Induced Vibration (VIV) may pose significant safety risks for offshore and marine energy installations. During offshore field operations, excessive loadings acting on marine risers often arise, posing operational risks. In this case study, experimental test results were utilized to analyze hydrodynamic in situ loadings acting on marine deep-sea risers, under ambient in situ environmental conditions. The current case study benchmarks a novel risk evaluation method, consisting of several critical components, that can be utilized in combination to estimate the reliability of multi-modal nonlinear dynamic systems. The first component is a dynamic system risks evaluation methodology, especially suitable for multi-modal structural (or environmental) dynamical systems, that had been experimentally measured across a representative duration, resulting in a jointly quasi-ergodic input timeseries. Another component being a novel extreme value prediction method, suitable for a wide range of engineering and industrial design applications. Multi-modal Gaidai structural risk (hazard) evaluation method yielded accurate predictions of the system’s failure (damage) risks, based on lab-measured riser dynamics. This case study aims at further benchmarking of recently developed a) state-of-the-art multidimensional reliability methodology, coupled with b) novel non-parametric deconvolution scheme, using raw experimental data as an input. It is the precise combination of these two above-mentioned methods a), b) that makes this case study of practical engineering value.