الفهرس 
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Abstract
Ships are usually designed by using the deterministic approach such as given by the classifications societies ,which ensure that the ships are built with an acceptable level of safety.
One of the catastrophic events of ships is collapse of the hull girder . Such an event will imply a risk of loss of human lives and a risk of polluting the environment dependent on ship type.
In order to avoid collapse of the hull , the deterministic design rules prescribe the maximum stress level., which not be exceeded under a prescribed bending moment. The seems to be inaccurate way to avoid on extremely complex event, since it cannot consider the interdependency of the possible modes of failures .. Moreover this approach cannot take into account the uncertainties involved in structural design . Such uncertainties may be due to simplified assumptions used in predicting the behavior of the structure under randomness of loading inability to determine the material properties . etc
In order to evaluate the reliability of hull collapse , however . it is necessary to have a tool which can accurately calculate the ultimate strength of the bull and furthermore , to have a probabilistic approach for evaluation the probability that the loading on the hull exceeds its strength.
An integrated method , which calculation the safety level of the hull exposed to vertical bending moment and considers the uncertainties mentioned above is then developed in the present study . This suggested method links between two methods , as follows:
1- The idealized Structure Unit Method is used to describe the non-linear behavior of the structural elements and to calculate the ultimate strength of the ship structure
2- The first order Reliability Method is used to determine the safety indices of structures for different modes of failure .