Significance of long-period ground motions on the seismic performance of transmission tower-line systems through multi-array shake table tests

Transmission tower-line systems (TTLSs), due to their expansive span, high rise, and significant nonlinearity, are particularly susceptible to long-period ground motions (LPGMs), which are featured by long periods and durations. The resultant resonant effect exacerbates the structural failure risk and severe functional degradation within transmission towers. However, previous studies have rarely utilized large-scale shake table tests to explore the effects of long-period characteristics, resulting in the seismic performance of TTLSs under LPGMs remaining unclear. In response, this study aims to experimentally investigate this phenomenon using multi-array shake table tests. Before this investigation, a large-scale experimental model of a TTLS was designed and fabricated, consisting of 1:20 scale transmission towers, 1:40 scale transmission lines, and mass blocks. Following the model's installation, measurement arrangement, and ground motion excitation planning, a series of shake table array tests were conducted to assess the impact of long-period characteristics on the seismic performance of the TTLS in terms of displacement, acceleration, and strain responses. The results indicate a significant amplification of the seismic responses of the TTLS by LPGMs and highlight the importance of incorporating the longperiod characteristics of ground motions in seismic analyses of TTLSs. This investigation is expected to provide valuable insights for TTLSs to effectively withstand seismic hazards.