The aim of the present paper is to establish a procedure of Structural Reliability Analysis (SRA) for the assessment of Ultimate Limit State (ULS) of ship's hull. A refined probabilistic models of both load (Wave-induced bending moment) and capacity (hull girder ultimate strength) have been derived by using direct calculation methods based on the latest analyzing techniques. An implemental procedure of SRA for estimating the ULS of typical merchant ships has been proposed. As application examples, a series of SRA by using First Order Reliability Method (FORM) has been performed and the annual failure probability of tanker, bulk carrier and container carrier for hull girder ULS has been calculated. It is found from the SRA results that the most dominant condition of tanker (VLCC) is full loading and sagging condition and the other conditions seem to be negligible. In case of large bulk carrier, hogging condition is also important because of the local load effect by sea and cargo pressures together with sagging condition. Contrary to the previous two cases, full loading and hogging condition is much influential in large container carrier. Based on the obtained failure probabilities of the applied ships, a reference value of the target failure probability for ULS assessment by using SRA has been mentioned.
Recently, Goal-Based new ship construction Standards (GBS) has been discussed in IMO (International Maritime Organization). Under such a situation, IACS (International Association of Classification Society) will also come to consider the development of a set of more refined Rule formulation based on GBS by using structural reliability analysis (SRA) in future. The aim of the present paper is to establish a procedure of SRA for the limit state assessment of ship's hull. Regarding the limit states to be considered for the assessment of ship structural safety, there are four important limit states for ship structural safety, namely, Serviceability Limit State (SLS), Ultimate Limit State (ULS), Fatigue Limit State (FLS) and Accidental Limit State (ALS).
