Reliability Analysis Of Spar Platform Based On Response Surface Method

Compared to other offshore platform,Spar platform owns more excellent motion performance and higher efficient economic benefits in the exploitation of oil and gas in the deep sea. With the expansion of the demand of energy, Spar platform is more and more popular in the exploitation of oil and gas in the deep sea. In the environment of deep sea, operating condition is very harsh, so the research of reliability of Spar platform in the bearing capacity limit state is very important. Take advantage of powerful finite element calculation of ANSYS, and combine the response surface method compiling procedure with MATLAB, simulate calculation of the reliability of Spar platform in different failure modes, which provides the technical reference of safety assessment of Spar platform.First of all, the paper introduce main deep-sea platform floating structure, and compare their advantages and disadvantages, at the same time, conclude and analyze accidents of platforms around the world. Introduce the development of Spar platform, elaborate the limitation and superiority of the three generations of Spar platform, the second generation Truss Spar platform is the research subject of this paper. Introduce the research status of reliability of offshore platform, stress the importance of the research of reliability of Spar platform.Secondly, compare and analysis the advantages and disadvantages of the center point methods the checking point methods Mento-Carlo method and the response surface method. For the complex structure of Spar platform, by caculating the expanding point in ANSYS, fit the response surface equation preliminary, compile procedure with MATLAB, by iteration calculation, we can get the reliability index that satisfy the accuracy requirement of engineering, at the same time provide flow diagram of the research of reliability of Spar platform.Analysis the uncertainty of wind-. wave and current, which is the elements of environment, determine the main failure modes conclude the Von Mises stress of the controlling sections exceed the allowable values, the displacement of the platform exceed the allowable values and the angle of the platform exceed the allowable values. Set up functions respectively, and calculate the reliability index and the response surface equation of the three failure modes. At last, considering cable corrosion effect on the reliability of Spar platform structure, calculate the reliability index of Spar platform which has serviced for 5 years,10 years,15years and 20 years. Conclude the rule of changes of reliability index, find the cable corrosion have less effect on the reliability of Spar platform, and analysis the reason of this phenomenon.The paper suggests some advice for design of Spar platform in terms of reliability, and also provides support for the study of safety testing and assessment for platform in service.