Environment Load Model of Platform Ice-Induced Fatigue Based on Ice-Induced Vibration Form

At present, it is immature to precisely evaluate the ice-induced fatigue life of platform. One of the key problems for accurate estimation of the ice-induced fatigue life is to establish the rational ice load model. A new method of establishing the environment load model to evaluate the ice-induced fatigue life is put forward based on the two basic vibration forms that are structure resonance and non-resonance existing in the ice-induced platform. Compared with the traditional classification method for ice-induced conditions, not only the ice thickness and the ice velocity of corresponding ice zone will be thought as the important influencing factors, but also the platform natural vibration characteristics will be considered in this method. Finally, based on this method, the environment load model of ice zone No.4 in China’s Bohai Sea is established to do the simulation test of node’s fatigue stress of one platform in this sea area. The results show that the bending stress can’t be ignored in the vulnerability analysis of the dynamic response of the ice-induced platform; the relation between the natural vibration frequency and the period of the ice broken must be considered to classify the work condition in the estimation of the platform ice-induced fatigue; the result can’t be guaranteed determinately more secure when the ice-induced fatigue analysis is conducted by simple amplifying the ice thickness or the ice velocity under the condition that ignores the nature frequency of the platform.