RELIABILITY BASED FATIGUE SAFETY ASSESSMENT OF OFFSHORE STRUCTURES IN ICE ZONE

摘要

The paper presents a probabilistic fatigue safety assessment procedure for offshore structures in ice zone, including establishing fatigue reliability model, determining fatigue loading probabilistic parameters, modeling fatigue resistance parameters and digital assessment on fatigue reliability. A new fatigue model based on random fatigue crack growth experiment is proposed to deal with loading interaction under stochastic ice force. There exists great probabilistic scatter in describing the fatigue loading and stress of structural member under ice loading. The paper investigates the statistical properties of annual ice term and ice strength. The normal distribution is used to describe the statistical model of ice term. The fatigue resistance parameters are discussed by presenting the experiment results of crack propagation under random ice loading history. Two digital evaluation approaches, i.e. distribution fitness method and life distribution method, are introduced to determine fatigue reliability of offshore structures under ice loading. Several engineering application examples are given.