[en] One of the main objectives of ship design and the building is the optimization of the payload, therefore, the reduction of the structure weight is an important factor. The structural weight of the superstructure on passenger and military ships represents between 25% and 40% of the total ship structural weight. The use of composite material for the construction of the superstructure has allowed a considerable structural weight reduction, however, the dissimilar behavior on the hybrid joint between naval steel deck and the composite panels superstructure is a difficulty presented in this type of construction, for this reason, this research will present a methodology to estimate the scantling of the hybrid joint, the first natural frequency of composite panels with reinforcements and recommendations for combining reinforced fiberglass with steel structures. The scantling of composite laminates with steel stiffeners is based on the macro-structural elastic model, following the formulas proposed by the American Bureau of Shipping-ABS. Then a microstructural study of the critical layer is carried out, as recommended by Lloyd's Register-LR Society, with some modifications proposed in the present investigation. In order to know the construction benefits of a superstructure built with reinforced fiberglass, three comparative analyses have been carried out that include: Analysis of the structural weight, Global analysis of stresses and Forced Vibration Analysis by propeller excitation. To perform the cost-benefit analysis of the composite materials applied in the superstructure, four material different construction options including fiberglass and steel were studied. For the comparative analysis, the form lines of a 36.80 m passenger yacht built-in 2005, with a naval steel hull and fiberglass superstructure with tubular steel structure, have been taken as a reference. From the analysis, it is concluded that the superstructure built with completely fiberglass material would have a greater benefit in weight reduction. Finally, a study of the possible hybrid joints that can be used between the steel deck and fiberglass superstructure is presented. To select the best hybrid joint proposal, a Finite Elements analysis was carried out to estimate the forces to which the hybrid joint will be subjected, then a critical layer analysis on the laminate is performed and finally, acceptance criteria are checked on interlaminar stresses for shear and normal.

[gl] Un dos obxectivos principais do deseño e construción dun barco é a optimización da carga útil, e para iso a redución do peso estrutural é un factor importante. O peso estrutural da superestrutura nos buques de pasaxeiros e militares representa entre o 25% e o 40% do peso estrutural total. O uso de material composto para a construción da superestrutura permitiu unha redución considerable do peso estrutural, sen embargo, a dificultade xérase debido ao comportamento diferente entre a conexión híbrida da cuberta de aceiro naval e a superestrutura de paneis compostos. Por este motivo, esta investigación presentará unha metodoloxía para estimar a escala da unión híbrida, a primeira frecuencia natural dos paneis compostos con reforzos e recomendacións para combinar fibra de vidro reforzada con estruturas de aceiro. A escala de laminados compostos con estruturas de aceiro baséase no modelo elástico macro-estrutural seguindo as fórmulas propostas pola American Bureau of Shipping-ABS. A continuación realízase un estudo crítico de estrutura micro-estrutural, tal e como propón o Lloyd's Register-LR [76], com algunhas modificacións propostas nesta investigación. Para coñecer os beneficios construtivos outorgados por unha superestrutura construída con fibra de vidro reforzada, realizáronse tres análises comparativas que inclúen: Análise do peso estrutural; Análise global de tensións equivalentes e Análise da resposta de vibración obrigada por excitación da hélice. Para facer a análise custo-beneficio de materiais compostos aplicados na superestrutura, estudáronse catro opcións de materiais empregando fibra de vidro reforzada e aceiro. Para a análise comparativa tomáronse como referencia un iate de pasaxeiros de 36,80 m construído en 2005, con casco de aceiro naval e superestrutura con paneis de fibra de vidro e estrutura de aceiro tubular. Da análise realizada, conclúese que a superestrutura construída con material completamente de fibra de vidro tería un maior beneficio na redución do peso. Por último, preséntase un estudo das posibles xuntas híbridas que se poden usar entre o tellado de aceiro e a superestrutura de fibra de vidro. Para seleccionar a mellor proposta de unión híbrida, fíxose unha análise mediante elementos finitos para estimar as forzas ás que estará sometida a unión híbrida, para logo facer unha análise de capa crítica no laminado e aplicar finalmente os criterios de aceptación entre os esforzos interlaminares tanto de corte como de tensión.