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Fixed jacket platform is an offshore structure consists of many elements such as leg and braces. Both legs and braces play an important role to support the structure from internal and external loads like structure its self and wave loads. Especially for jacket leg, the deck load is distributed to all jacket leg to support deck structure. Besides, jacket leg also resists wave loads in horizontal direction. Due to the axial load caused by deck and horizontal load caused by wave, these loads act periodically on jacket leg. Therefore, the analysis of fatigue life to jacket leg should be performed for structural design. The present study focuses on fatigue life prediction on jacket leg under axial and wave load. The numerical method is conducted to analyze fatigue life on jacket leg. It is found that the fatigue life due to axial and wave loads are 185 and 108 years, respectively.

Many types of equipment placed at the deck structure of an offshore structure. The equipment is used as production facilities, exploitation, explorations, and so on. Besides, loads are also acting on the deck and make it becomes heavy and need to be analyzed. In this study, the main deck pipe subjected to the deaerator of the jacket structure is analyzed. The modeling and analysis are conducted using the finite element method. The deaerator is assumed as a static load acting on the pipe of the main deck. The result obtained by the finite element method is presented in terms of the stress-strain curve and deformation.

The hull girder plays an important role against those loads and to describe the structural behavior under longitudinal bending. The hull cross-sectional properties have a significant contribution to the ultimate strength investigation. Therefore, the influence of the element section properties to the ultimate hull girder strength must be evaluated. The objective of the present study is to calculate the ultimate hull girder strength considering the element section properties subjected to longitudinal bending. Two double-hull tankers are taken with the same dimension, but different from the element section properties characteristic such as number, dimension, and type of the stiffeners located on the bottom, shell and deck parts. The basic formula is adopted to calculate element section properties of the hull girder for double hull tanker. The double hull tanker is modeled as a cross-section having the stiffeners and attached plating. The stress due to the difference of the element section properties is less than allowable stress.