Structure Reliability Analysis Of A Single-hull And A Double-hull Bulk Carriers

For bulk carriers, the side shell is one of the weakest parts of the hull. In order to solve these problems which appear in hull structure and the process of managing, and improve the security of bulk carriers especially the senile bulk carriers, the double-hull structure of bulk carriers is put to the schedule of IMO increasingly.In this article, the distributions of still-water an wave-induced bending moments are studied. Then the ultimate collapse bending moment of the midship cross section is used as the bias for the reliability formulation. Other than before, the gradually-destroy method is used. A hybrid approach based on the combination of Monte Carlo simulation(MCS) technique and the first order reliability method(FORM) is developed to quantify the small probability of a hull girder under longitudinal bending. The probability distribution of the ultimate strength is determined by propagation of the uncertainties associated with hull geometric and material property parameters via a small number of Monte Carlo simulations. The FORM based solution module is then applied to compute the probability of failure and the reliability index.An example of a bulk carrier is given, the ultimate moment and the reliability index are calculated in two forms: a single-hull and a double-hull. The result indicate that the double-hull structure has little effects on the longitudinal strength. The sensitivity vector is also calculated, the result indicate that: in reliability calculate, the most important random variables is the ultimate moment, the following is wave-induced bending moments, and the still-water bending moments and other random variables are less important.