Analysis of existing offshore structures considering structural damage to investigate a vertical axis wind tower

The most common offshore structures are the Jackets which are tools used to extract the oil and natural gas in relative low water depth particularly exist in Adriatic Sea and a lot of them have been constructed in the last 50 years. When the offshore oil and gas resources exhaust, these structures must be replaced to another region containing underground resources or removed if reaching the design life, furthermore, another solution can be considered: changing life of the future working of these platforms by applying renewable energy and alternating them into offshore wind towers. This thesis proposes to study and examine the stiffness matrix of an existing Jacket which consider damaged components for reliability analysis of offshore installations. In this research it was used the 8-step simplified methodology which includes several step to analyze the ability of the offshore jacket structure to examine if it is tolerable to endure the effect of wind or wave loads (environmental forces) more than usual by simulating a minimizing of the stiffness matrix using several random cases which they are ten cases, firstly minimizing in the x direction ( 5 cases) and lastly in y direction and then comparing each of these cases with the original case .It was presented two of the most critical cases to show the effect of each step one in x direction and the other in y direction consequently. At the end it is showed that even the structure jacket is 50 years old it is standable and bearable to face some reduction of its stiffness