Influence of seismic duration on performance assessment: application to self-centering concrete frames

It is widely acknowledged that seismic duration has significant impacts on structural responses for traditional concrete frames. However, it still has not been comprehensively investigated towards self-centering systems, given the unique nonlinear behaviors and performance. This study investigates the influence of seismic duration on deformation responses, energy demands, damage progress and collapse capacity for self-centering concrete frames (SCCF). Six SCCFs with varying heights and structural features are designed and examined through nonlinear time history analyses utilizing two spectrally equivalent record sets with distinct durations. The results show a negligible correlation between seismic duration and peak deformations, yet earthquakes with shorter durations tend to enlarge residual deformations in SCCFs. Long-duration earthquakes impose significantly higher energy demands, negatively impacting damage development in SCCFs, while the energy distribution within structures remains consistent across the two record sets. Furthermore, SCCFs are observed to experience increased risks of collapse under earthquakes with longer durations, with the impact being more pronounced in SCCFs with larger self-centering parameters. Additionally, the duration-blind record set suggested in FEMA P695 is found to be inadequate for assessing collapse capacity for systems subjected to long-duration earthquakes. Consequently, it underscores the necessity of explicitly considering the duration effect in seismic designs and performance evaluations for SCCFs.