Analysis And Calculation Of Ultimate Strength For Ship Hulls By Direct Calculation Method

The ultimate load bearing capacity of ship hull structure is an important index expressing the safety and reliability of the structure. After many years of research work and development, many methods for the ultimate strength calculation of ship hulls are developed. But, the researches need lucubrate to acquire some analysis methods and computer programs which are mature in theory, easy in application, and accurate in results.Direct calculation method, as one of the ultimate strength calculation methods, is easy in operation, and can acquire accurate results if the assume of stress distribution for ships in the ultimate limit state is reasonable. The ultimate strength of the intact hull and the remaining strength of the damaged hull are investigated mainly based on direct calculation method in this thesis. The main content of this thesis are as follows:1. Derives the formulas for calculating the ultimate strength of stiffened plate in which the stiffener collapse with the plane together, and develops computer program based on theory, its reliability is validated, through comparing the calculation results with the ones from other papers.2. Derives the formulas for calculating the ultimate strength of ships based on direct calculation method, and develop the program to calculate the ultimate strength of intact ships and damaged ships.3. Assuming the stress distribution for single hull and double hull ships in the ultimate limit state, then calculating the ultimate strength for box girders and actual ships. The results by the thesis are compared with the ones from the progressive collapse method and other papers. It shows that the stress distribution assumed in this thesis is reasonable, and can be used in practical calculation.4. After observing the structure form and calculating the ultimate strength for the inland double-hull ships with the progressive collapse method, the thesis assumes a stress distribution for inland double-hull ships in the ultimate limit state.Through the comparisons among the results from many actual ships and models, it verifies that the stress distribution for different kinds of ships assumed in this thesis is reasonable, the developed programs are effective, and can be used to calculate the ultimate strength for these kinds of ships.