SAMPLE-SPECIFIC LINEARIZATION IN RELIABILITY-ANALYSIS OF OFFSHORE STRUCTURES

The reliability analysis of off-shore structures under dynamic non-Gau ssian wave, wind and water current loading is considered using an outc rossing approach and directional simulation in the space of the load p rocesses. To circumvent the non-Gaussianity of the load processes for which results for mean outcrossing rate are not generally available, t he ''sample-specific linearization method'' is proposed. This method i s based on well-known results for Gaussian processes and uses the func tional relationships between the non-Gaussian wave, wind and water cur rent loads and the corresponding velocities. The proposed method is ap plied to a simple model off-shore structure. The structure is analyzed also to obtain probability of failure by means of Monte Carlo simulat ion and using time domain simulation of the load processes. This was f ound to be extremely expensive of computer time. The results were foun d to compare very favourably with those obtained by the proposed metho d, both in terms of accuracy and computation required. Copyright (C) 1 996 Elsevier Science Ltd.