Vector Form Intrinsic Finite Element Analysis Of Offshore Substation Based On Plate-beam Structure

The safety of offshore substation affects the operation of the whole wind farm,so it is of great engineering significance to analyze the characteristics of offshore substation under multiple operating conditions.In this paper,based on the VFIFE method,combined with the specific marine environmental conditions,the VFIFE calculation method of offshore substation under various working conditions was established,and its calculation and analysis were carried out.This paper based on the theory of VFIFE beam element and thin plate element,the internal force solving process of them was deduced,and the coupling algorithm of thin plate element and beam element was proposed.At the same time,the elastic-plastic fiber beam element and elastic-plastic plate element were introduced,and the stressstrain relationship was deduced.The problems of geometric nonlinearity and material nonlinearity in structural analysis when plate-beam elements coexist were solved.This paper the VFIFE model of offshore substation of pure beam system and platebeam system was established,and it was calculated,compared and verified.The results of the VFIFE program were in good agreement with those of the marine structure analysis software,and the most relative error was less than 5%,absolute error was 2mm,which proved the applicability and accuracy of the VFIFE method.The plate-beam coupling model can better reflect the real structure of the offshore substation.The storm surge condition was calculated by using the offshore substation model based on the plate-beam structure,the internal force distribution and motion response of the offshore substation were analyzed,and the influence of different environmental load incident angle on the structure was explored.When the load incident angle is 90 °,the displacement and stress of the offshore substation structure reached max value,and the element is prone to plastic deformation,so the member of the wave face should be paid attention to and strengthened in the design.This paper combined with the incremental dynamic analysis method,the seismic collapse of the offshore substation was studied.The effects of different seismic loading control modes on the structural response were explored and compared with the traditional finite element method.At the same time,the top displacement of substation,the deformation of each deck and the mode of inter-story displacement were analyzed.The calculated results were in good agreement with the results of marine structure analysis software,which showed the effectiveness of the proposed method.The upper part of the offshore substation is relatively special,and its inter-story displacement mode is different from that of the traditional multi-story steel structure,so fine modeling should be carried out in the analysis of seismic collapse.