Dynamic responses and seismic loss assessment of self-centering frames under pulse-like ground motions

Abstract

Near-fault ground motions (NFGMs) are characterized by significant velocity pulses, which pose a heightened seismic risk to structures and have garnered increasing attention in recent years. However, quantitative research on the seismic loss of self-centering structures under NFGMs remains limited. The study systematically investigated the dynamic responses, damage states, and post-earthquake seismic loss of self-centering friction frames subjected to NFGMs with varying normalized pulse periods (T_p/T₁). A five-story self-centering friction frame is designed, and a simplified numerical analysis model is developed using the finite element software MSC.Marc. A total of 8 sets of NFGMs, with T_p/T₁ ratios ranging from 0.5 to 6, are selected for analysis. Incremental dynamic analysis is conducted to quantify the influence of T_p/T₁ on the self-centering frame’s dynamic responses, damage states, and seismic loss. The results reveal that as the intensity of ground motion increases, the normalized pulse period that most adversely affects the inter-story drift ratio and structural damage also tends to rise. Additionally, NFGMs with a T_p/T₁ ratio of 0.5 are more likely to induce higher-order vibration modes of the self-centering frame at low seismic intensity. When seismic loss is used as the seismic performance indicator, NFGMs with T_p/T₁ of between 2 and 4 are found to cause the most significant seismic loss of the self-centering frame.