Mainshock‐consistent ground motion record selection for aftershock sequences

Abstract

In recent years, the additional risk posed to the built environment due to aftershock sequences and triggered events has been brought to attention, and several efforts have been directed towards developing fragility functions for structures in damaged conditions. Despite this rise of interest, a rather fundamental component for such tasks, namely that of aftershock ground motion record selection, has remained under-scrutinized. Herein, we propose a pragmatic procedure that can be applied for the selection of mainshock-aftershock ground motion pairs using consistent causal parameters and accounting for the correlation between their spectral accelerations. In addition, a structural analysis strategy that can be employed for the analytical derivation of damage-dependent fragility functions is outlined and presented through a case study. A more conventional back-to-back IDA analysis is also carried out in order to compare the derived damagedependent fragility functions with the ones obtained with the proposed procedure. The results indicate that record selection remains a crucial factor even when assessing the structural vulnerability of damaged buildings, and should thus be treated cautiously. K E Y W O R D Saftershock risk, damage accumulation, damage-dependent fragility functions, ground motion record selection, mainshock-aftershock sequences

Effects of ground-motion sequences on fragility and vulnerability of case-study reinforced concrete frames

“…However, most of these studies (i.e., Raghunandan et al 2015; Burton and Sharma 2017) apply the developed artificial MS-AS sequences in conjunction with the IDA approach, implying excessive scaling on the records and related issues (e.g., Miano et al 2018). More recently, Papadopoulos et al (2020) developed an advanced strategy combining spectrally compatible ground motions into MS-AS sequences that are representative of potential rupture scenarios, by implementing the appropriate triggering mechanisms and recently-developed MS-AS spectral acceleration correlation models.…”

“…The authors showed that the median values of aftershock fragility curves are reduced by 14-46% compared to the undamaged state and the reduction is much more significant when the initial mainshock DS is large. Some studies have also focused on different aspects such as MS-AS record/sequence selection, with special focus on hazard consistency (e.g., Goda 2015;Papadopoulos et al 2020).…”

Hysteretic energy‐based state‐dependent fragility for ground‐motion sequences

“…This approach does not require a site‐specific, hazard‐consistent record selection (e.g. Papadopoulos et al 3 …”

“…state-dependent fragility). Most studies derive seismic fragility in terms of maximum interstorey drift thresholds [3][4][5] , although in some cases this is considered in conjunction with the residual drift 6 . This may create inconsistencies in the resulting statistical models due to inappropriate consideration of damage accumulation.…”

“…This approach does not require a site-specific, hazard-consistent record selection (e.g. Papadopoulos et al 3 ), and requires none-to-moderate scaling of the ground motions. It is worth mentioning that catastrophic effects due to low-cycle fatigue (e.g.…”