Effects of ground motion duration on dynamic responses, fragility, and seismic loss of self-centering frames

This paper investigates the impact of ground motion duration on the seismic performance of a five-story self-centering friction frame (SCFF) structure. Firstly, this paper proposes and designs a five-story self-centering friction frame (SCFF) structure, subsequently establishing a numerical analysis model. Two sets of spectrally equivalent ground motion records, categorized as long- duration (LD) and short-duration (SD), are constructed. Subsequently, nonlinear incremental dynamic analysis is performed on the SCFF to quantify the impact of duration on its dynamic responses, fragility, and seismic loss. The results demonstrate that while the LD ground motion has negligible influence on peak floor acceleration, it amplifies the inter-story drift ratio of the SCFF under strong earthquakes. This amplification effect intensifies with increasing seismic intensity. Notably, the LD ground motion also reduces the collapse resistance and post-earthquake recovery capacity of SCFF by 9.5 % and 10.1 %, respectively. Furthermore, it significantly magnifies the seismic loss of SCFF when the structure enters strong nonlinear state. When the seismic intensity reaches 1.3 g, the LD ground motion amplifies the total structural seismic loss by a factor of approximately 1.8. However, when considering the expected annual loss as a metric, the LD set only increases the expected annual loss by 2.5 %.