Shake table test and seismic fragility analysis of transmission tower-line system considering duration effect

•Shake table tests on a TTLS subjected to LDGMs and SDGMs are conducted.•A detailed FEM of the TTLS is developed in ABAQUS and experimentally validated.•The seismic response and progressive collapse of the TTLS are investigated.•The seismic fragility and loss of the TTLS are analyzed considering duration effects. Although extensive attention has been devoted to the influence of ground motion duration on the seismic performance of various structures, the integration of the duration effect into the seismic analysis of transmission tower-line systems (TTLSs) has been rarely studied, leading to a lack of understanding regarding the relationship between the ground motion duration and the seismic response of TTLSs. This paper aims to quantify the duration effect on the structural performance and seismic fragility of a TTLS through shake table tests and numerical simulations. To achieve this goal, a reduced-scale experimental model of a TTLS is carefully designed and fabricated, and a group of ground motions with contrasting durations is chosen using a spectral matching method. Subsequently, shake table tests are conducted to examine the duration effect on the seismic responses of the TTLS. The recorded data indicates that long-duration ground motions (LDGMs) significantly amplify the seismic responses and have the potential to degrade the structural performance. Furthermore, a validated finite element model of the TTLS is employed to compute its nonlinear responses from elastic behavior to complete plasticity utilizing incremental dynamic analysis. Probabilistic assessments are also conducted to investigate the seismic fragility and loss of the TTLS. The findings reveal higher damage probabilities and more severe losses caused by LDGMs, emphasizing the importance of considering the duration effect in the seismic performance assessment of TTLSs. This investigation contributes to a meaningful exploration for reliably assessing the seismic capacity of TTLSs while accounting for the duration effects.