Generating an ensemble of mutually exclusive and exhaustive waves targeted for extreme responses

Abstract

To examine the reliability or performance of marine systems related to dynamic time-varying responses, time domain simulation may be required. But for long durations, brute-force simulation is clearly not feasible from a computational point of view to examine converged extreme value statistics. An additional challenge is defining a set of mutually exclusive and exhaustive wave excitation records which excite the desired extreme response(s). To address these challenges, this work develops a non-linear Design Loads Generator (NL-DLG) process which links wave profiles targeted for extreme responses generated via response-conditioning wave techniques to a probabilistic framework which examines the possible correlation or mutual exclusivity between those wave profiles. The end result is an ensemble of short targeted wave profiles which excite converged extreme value return-period statistics of a defined response that may be excited by multiple correlated processes. The method of the NL-DLG process is explained by applying it towards rare wave groups, where the result is an ensemble of short wave profiles which contain extreme occurrences of different wave groups targeted for the defined exposure duration. These generated wave excitation profiles are compared to physical data from the Pt. Reyes buoy and then numerical simulations are employed to consider rarer events.