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Assessment of existing jacket type offshore platform against environmental wave loading hazard is the central component of this work. Two general approaches exist in this context, deterministic and probabilistic assessment. In this study, a new probabilistic method (reliability analysis) to assess offshore structures under environmental loading (extreme wave) is introduced. Before describing this approach, several necessary elements such as collapse analysis, sampling methods and wave hazard analysis should be investigated. First of all, deterministic assessment of SPD2 platform located in Persian Gulf, which is the case study considered in this dissertation, is conducted utilizing... 

In this thesis, multi-degree-of-freedom and finite element methods are utilized to simulate the dynamic behavior of fixed offshore structures under the wave and the earthquake excitations. In the field of seismic loading, seismic response of the platform is determined with the response spectrum analysis (RSA), time history analysis (THA) and endurance time (ET) methods. The accuracy and the computational cost of the ET method are compared with the RSA and THA methods. The results indicate that despite the RSA method, the ET method can estimate the nonlinear behavior of these types of structures. Moreover, in comparison with the THA method, the computational burden decreases to about 5% while... 

Assessment of existing jacket type offshore platforms in Persian Gulf for life extension is of great importance in the field of offshore platforms in recent years. The main question to answer is whether an existing platform is safe enough to be used beyond the design life. Evaluation of existing jacket type offshore platforms under extreme environmental (wave) loading in Persian Gulf is a part of this major assessment. Two general approaches exist in this context, deterministic and probabilistic assessment. In this thesis, a new probabilistic method (reliability analysis) to assess offshore structures under environmental loading (extreme wave) is introduced. This method is a... 

Assessment of existing jacket-type offshore platforms in Persian Gulf for life extension or operative conditions is a major concern for oil offshore companies in recent years. Significant damage to offshore platforms as well as their contents will induce significant losses such as financial losses, fatalities and casualties. On the other hand, extreme waves or earthquakes are low-probability, large-consequence and large-uncertainty hazards that can affect these critical facilities; therefore, the assessment of existing offshore platforms subjected to each of these sources can be successfully carried out by a probabilistic approach. In this dissertation, a unique probabilistic... 

Offshore platforms are one of the most important structures in oil-rich countries, so that their economic benefit makes it very expensive to stop their usage. Therefore, it is essential that their performance is not disrupted by earthquake or the tidal waves made by severe storms. According to statistics many of the offshore platforms of their design life pass and need an important loss inspection. The assessment of existing platforms is a relatively new process. The lack of comprehensive standard creates some difficulty in establishing performance requirements, on a case by case basis depending upon the risks associated with the future operations of the platform. In this study the criteria... 

Dynamic increasing amplitude and period (DIAP) [1] is a time-domain analysis methodology developed based on endurance time (ET) analysis method [2], which can be used to evaluate the response of marine structures when encounters a continuous loading, such as storm conditions. In this method, instead of using separate records with different intensities, a single loading record with an increasing intensity over time is used for structural analysis. The ability to enter spectral concepts, considering the effects of waves with different frequencies and amplitudes, taking into account the effects of randomness of waves and the possibility of short duration analysis are some of the specific... 

Nowadays, according to existence of oil resources in offshore areas and the necessity of extracting, constructing of offshore platforms is developed. The design of these structures has high effect on the cost of construction and maintenance and the performance under the loads such as wave, earthquake, impact, etc. Therefore, if the analysis of platform structure is more accurate the evaluation of the behavior and consequently the better design in different conditions is better. In this thesis, a modification of Endurance Wave Analysis (EWA) in evaluation of offshore structures is introduced in this study. EWA is a new method to predict the response of offshore structures in different sea...