Abstract
After a major earthquake, multiple aftershocks often occur, and there is typically insufficient time to repair or reinforce structures between these events. Consequently, structures damaged in the mainshock may suffer greater damage or even collapse during subsequent aftershocks. Evaluating the seismic performance of reinforced concrete TV (RC-TV) towers is essential due to their critical role in signal propagation. Currently, the seismic design code and structural performance evaluation for RC-TV towers focus only on a single earthquake, overestimating the structure's seismic capacity during continuous seismic events. Because the mechanisms of mainshock and aftershock differ, the characteristics of aftershock can vary significantly from those of the mainshock. Therefore, this paper proposes an analytical framework to study the effects of mainshock-aftershock (MS-AS) sequence characteristics—such as ground motion magnitude, rupture distance, duration, and frequency content—on the aftershock fragility of RC-TV towers. A series of nonlinear time history analyses were conducted using real MS-AS sequence records, and the fragility curves of aftershocks following different mainshocks were obtained. The results show that the aftershock fragility of the structure is more affected by MS-AS sequences with large magnitude, distant fault, long duration and low frequency. As the degree of structural damage from the mainshock increases, the influence of aftershock fragility becomes more pronounced. This study comprehensively and reliably analyzes and evaluates the seismic performance of RC-TV towers under MS-AS sequences with different ground motion characteristics, providing valuable references for designers in safety design and managers in daily maintenance.