Shaking Table Testing of a Wind Turbine Exposed to Stochastic Near-Fault Pulse-Like Ground Motions

Near-fault ground motions with strong velocity pulses can significantly influence the seismic response of wind turbine towers; however, their effects have rarely been isolated experimentally under controlled spectral conditions. This study presents shaking table tests of a scaled wind turbine subjected to stochastic nonpulse and pulse-like ground motions, including nonpulse ground motions (NPGM), single-pulse ground motions, and multipulse ground motions (MPGM), generated using the spectral representation method. By removing the pulse components from the time histories, the three categories are shown to exhibit nearly identical elastic response spectra, thereby enabling a systematic experimental comparison that isolates the effects of pulse characteristics. The simulated ground motions are applied in shaking table tests, and the dynamic properties, acceleration responses, displacement demands, and shear forces of the tower are evaluated using statistical measures, including mean values, standard deviations, and probability density distributions. The results indicate that responses induced by NPGM are consistently lower than those induced by pulse-like ground motions, while MPGM produce the largest acceleration, displacement, and shear demands. Significant drift amplification is observed in the upper portion of the tower under pulse-type excitations, particularly for multipulse ground motions. The experimental results demonstrate that pulse characteristics, especially the presence of multiple pulses, play a critical role in amplifying the seismic demands of wind turbine towers. These findings highlight the importance of explicitly considering pulse effects in the seismic assessment and design of wind energy structures.