| China is a large maritime country with a vast maritime area.As the demand for energy increases,so does the number of offshore platforms.Offshore platform is the basic infrastructure for the exploitation of offshore oil and gas resources.Its structure is complex and its cost is expensive.How to balance the relationship between safety and economy and design a safe and economic offshore platform structure is of great significance.The function of the platform structure is different,the actual service life of the structure is different.The actual life of the structure varies with the amount of oil stored in the oil field,and the traditional structural design method cannot design the structure according to the different life of the structure,which may lead to the redundant life of the designed structure and the cost waste,and may also lead to the insufficient life of the designed structure and the security threat.Therefore,it is very necessary to establish the platform structure design method with different life.In this paper,the target reliability index of offshore platforms with different life spans are determined by quality of life criteria,and a new method of structural life design for offshore platforms is established based on this.At the same time,considering the variation of resistance with time,the life design method of offshore platform structural components based on time variation of resistance is also established,which has a very important reference value for the perfection of design code.The main research contents are as follows:1.Based on the quality of life in existing criteria to determine the target reliability index based on research,put forward by the quality of life criterion to determine offshore platform structures methods and steps of the target reliability index,which determine the different life of the target reliability index of the offshore platform structures,for the life design method of offshore platform structural components laid a foundation.2.To inherit the original design method based on the coefficient,the target reliability index into subentry coefficient form,based on the target reliability index is obtained,determines the different life of offshore platform structures design of each partial coefficient,finally get the practical design expression of offshore platform structures,provides a theoretical basis for the improvement of the design specification.3.Determine the factors that affect the resistance attenuation,build the structural resistance attenuation models under fatigue and corrosion conditions respectively,and then conduct reliability analysis on the structural components to determine the reliability index attenuation law.According to the attenuation law of the reliability index and the target reliability index of the offshore platform with different service life,the target reliability index that should be achieved in the design of the offshore platform structure is deduced,and the life design method of the offshore platform structure considering the fatigue and corrosion conditions is established. |
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