COMPUTATIONAL MECHANICS New Trends and Applications E. Oñate and S. R. Idelsohn (Eds.) ©CIMNE, Barcelona, Spain 1998 1 AN IMPROVED NUMERICAL MODEL FOR CALCULATING SHIP HULL FRAME TRANSVERSAL STRUCTURE Oscar B. Augusto * , Ademar A. Cardoso † * Naval Architecture and Marine Engineering Department University of Sao Paulo Sao Paulo, Brazil e-mail: obaugust@usp.br † Naval Architecture and Marine Engineering Department University of Sao Paulo Sao Paulo, Brazil e-mail: ademar@usp.br Key words: Ship Structure, Transversal Frame, Finite Elements. Abstract. Reinforced panels basically compose a ship structure like many other light structures. Nowadays the most usual method for stress calculating of these structures is the Finite Element Method, where the hull plating are modeled as shells elements and stiffener beams as membrane elements as well as beam elements with attached plate. These models are convenient when used for analysis problems where generally few simulations are done to diagnostic any structure. Nevertheless when the problem is design or synthesis high accuracy simpler models are necessary because in despite of the search or optimization algorithm used hundred of simulations are often necessary until the final design is attained. For these situations we have proposed a two dimensional simplified model to calculate stress and deflections of the transverse ring frame of a hull structure, trying to reduce the simulation time and consequently the total time in the optimizing global process. The model consists in calculating an isolated ring frame of the hull structure prescribing adequate boundary conditions that will reconstruct the main behavior of the isolated structure when it was with the whole structure. The results were compared with those obtained by three-dimensional models and the accuracy attained is compatible even for analysis problems.