Seismic Reliability Analysis For Aged Offshore Platform

At present, in our country the service year of most offshore platforms are much long. Some of the platforms have been servicing for as long as or over their original design lifetime, and they are stepping into the later service period, and ageing trend of the platform is serious. At present, we are aimed to build the saving type society, so how to tap the later power of the existing platforms and guarantee the seismic behavior of the aged platforms have automatically become a research subject with great practical significance. The dissertation focuses on seismic reliability analysis for aged offshore platform, which is a part of the "863" High Technology Research and Development Program of China (2006AA09Z355) of "Research on Life Extension Technology for Aged Offshore Platforms" and the Shandong Natural Science Foundation Program (200637b2804040) of "Research on Virtual Safety Theory and Application for Offshore Structure".The fine finite element models for the jacket platform with different ageing features are built. The response of the aged jacket platform to the whole seismic time-process is analyzed making use of time domain analysis, and the affections of crack damage, collision damage, corruption, lost components, scour around piles foundation along with marine growth to the general rule of ageing jacket platform's seismic response are summed up. The finite element model of solid-liquid coupling on oil storage jacket platform is built, and the dynamic behavior is studied. The change for the frequency, vibration mode of the structural system under the situation with different depth in oil storage tank and the reaction of the oil storage jacket platform under the affection of seismic load are discussed, which can provide reference basis for shock absorption of oil storage jacket platform. Based on whole stepwise push method, an approximation method to evaluate the ultimate seismic capacity of aged jacket platform is proposed. The selection method for the main failure mode of aged platform under seismic load is deduced through the discussion of the structure failure modes under disaster load, and this method is verified through examples. The seismic reliability index of aged jacket platform is calculated. At the same time, the infection of corruption and oil storage depth to seismic reliability of aged platform is analyzed. The finite element model of aged jack-up drilling platform is built. The stability for spud leg of aged jack-up drilling platform is analyzed according to the CCS standard. The feature and forming reason for aging of jack-up drilling platform are explored, the seismic response analysis of jack-up drilling platform is carried out making use of the time domain method and frequency domain method, and the affection of corruption to the seismic reliability index of jack-up platform is analyzed in this paper.