الفهرس 
TYPES OF OFFSHORE STRUCTURESOnly 14 pages are availabe for public view
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Abstract
Offshore structures are very important and they are growing every day because of the lack of oil resources on the land. These important structures are subjected to random wave loads and severe environmental conditions. This research presents a review of the common types of offshore structures, detailed method used to calculate forces due to random waves, and furnish laboratory modeling of offshore structures according to modeling laws. The main goal of this dissertation is to study the behavior of these important structures under the main load which is the random waves and to identify the existence of damage in its members. Damage identification in early stage is a critical issue and allows saving human lives and tremendous money spent in the design and the construction of these structures. The author chose jacket platforms to perform his studies since they are the most common types used in offshore platforms. A scaled model structure was designed and fabricated to imitate the behavior of a real prototype structure. The model was fabricated from ABS material to a geometrical scale of 1:30. The chosen real structure is a typical four-legged jacket structure located in a water depth of 73m. The model was equipped with necessary accelerometers and strain gages. The experiments were conducted in air and in water. The in-water experiments were done in a wave tank equipped with a wave generating system. Three spectra were used in the experiments. The scaled model structure was modeled by finite element to compare the theoretical and the experimental results. A good correlation was obtained in both values and trends. The effects of different parameters on the dynamic behavior of the model structure were also studied. The thesis also provides a way to estimate reaction force and moment based on the experimental results. The random decrement technique (randomdec) was used to identify the damage in the model structure in both air and water. The method was very successful in finding out the damage in most of the cases