Seismic Performance And Failure Mode Of On-shore Wind Turbine Structure Under Near-fault Ground Motions Considering Vertical And Pulse Effect

As the installed capacity of wind turbines continues to increase,the scope of distribution continues to expand.A considerable number of wind turbines are inevitably established in areas with high seismic intensity.Since the beginning of this century,global seismic activity has entered a period of high incidence,and destructive strong earthquakes have occurred frequently,especially the structural damage near the near-fault area is more serious.Therefore,it is of great significance to study the dynamic response and failure mode of wind turbine structures under near-fault ground motions.At present,the study on the influence of wind turbine structures under the near-fault ground motion is in the preliminary analysis stage,mainly focusing on fling step of near-fault ground motions seismic response on the wind turbine structure.The nonlinear analysis of wind turbine structures under ground motion mainly compares the damage analysis of wind turbine structures under near-fault and far-field ground motions,and the nonlinear analysis of wind turbine structures under periodic vibration with different frequency spectrum characteristics.Few studies have been conducted on wind turbine structures built on different site types cons idering near-faults,velocity pulses and dynamic responses to far-field ground motions.Among them,the influence of the significant vertical acceleration in the near-fault ground motion on the wind turbine structure also needs to be studied.In view of this,the main content of this study consists of the following three aspects.Firstly,according to the rich velocity pulses of near-fault ground motion and the significant vertical acceleration component,the difference betw een the spectral characteristic of near-fault vertical ground motion and typical far-field ground motion is analyzed,and the design velocity response spectrum of near-fault pulsed ground motion is studied for the low damping characteristics of wind turbines.Secondly,the 2 MW three-blade horizontal axis wind turbine in a tens of mi llions of wind farms is used as the prototype,and the finite element software ANASYS is used to establish an integrated blade-nacelle-tower finite element model.According to the characteristics of shear wave velocity,cover thickness,focal distance and whether it contains velocity pulses,a total of 71 near-field non-pulse and near-field pulse-containing and far-field vibrations on class ?,? and ? sites were selected.The dynamic response of the wind turbine structure considering the site effect under different earthquake types is studied,and the effects of different ground motions on the displacement,acceleration,stress,and bending moment,shear force and torque of the wind turbine structure are determined.Finally,considering the vertical acceleration effect of near-fault ground motion and the influence of low-frequency components in far-field vibration,and analyzing the failure mode of wind turbines from the aspects of displacement time history,plastic dissipation energy and plastic hinge development process.Meanwhile,the peak acceleration of ground motion is used as the strength parameter to study the failure probability of wind turbine structures under the action of near-fault,typical far-field and ordinary far-field earthquakes.