Study on Fatigue Reliability Analysis of Tubular Joints for Ice-resistant Offshore Platform Based on Kriging Model

Abstract: Ice load acting on the structure is the key factor of the structural design and safe operation in the high latitude waters.For the cold regions encountering frost,ice force usually has serious influence on the structure.At present,tubular joint fatigue problem for offshore platform in Bohai bay,which is induced by dynamic response of platform under ice load has becoming more and more serious.It is quite proper to study by using structural reliability theory for the fatigue of structures in ship and offshore units,which is affected by a large amount of uncertain factors.Fatigue reliability analysis for the safety of structure in the aspect of fatigue can make more reasonable estimatment than deterministic method.The ice fatigue environmental model in JZ20-2 Sea area and the ice spectrum of conical structures are established based on field data of ice condition and ice load in Bohai bay in this paper.At the same time,the ice-reduced fatigue of JZ20-2NW platform is analysed with spectral analysis method in detail.According to the fatigue environment in the ice zone and the ice-force spectrum function,this paper establishes the approximate calculation method of hot spot stress with respect to the ice velocity and thickness which is called Kriging interpolation.The nolinear implicit relationship of input parameters and responses is established based on ANSYS numerical simulation.At the precondition of keeping precision, quicker the caculate speed.Finally,the fatigue reliability of JZ20-2NW platform in Bohai bay is evaluated.The results demonstrate that the method proposed in this paper is rational and efficient…
Key words: Jacket platform; Ice-induced fatigue; spetrum analysis; Fatigue reliability; Kriging interpolation

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