Seismic vulnerability assessment of ageing reinforced concrete structures under real mainshock-aftershock ground motions

Abstract

Ageing structures located in moderate to high seismicity regions are exposed to multiple natural stressors during their lifetime. Large earthquake events coupled with environmental aggressive agents increase the progressive failure probability of these structures. The accumulated damage during the main earthquake event might be exacerbated by its following aftershocks. This might result in catastrophic failure of these structures, and consequently, result in several socio-economic losses. Taking such progressive deterioration mechanism into consideration, the current study presents a framework to assess the vulnerability of ageing Reinforced Concrete (RC) frames subject to real Mainshock-Aftershock (MS-AS) ground motion sequences. Employing an advanced fibre-based finite element modelling technique, the nonlinear static and dynamic behaviour of a case-study RC frame with various ages is simulated under 48 real MS-AS record pairs. Quantifying corrosion-variant damage states, the age-specific fragility curves are developed for the considered structure under both single MS events and MS-AS sequences. It was found that the severely corroded RC frames are most likely to collapse before the second event comes up.Moreover, results show that the PGA ratio of AS to MS plays a critical role in seismic vulnerability assessment of highly corrosion-damaged RC frames.

Seismic Fragility Curves of RC Buildings Subjected to Aging

“…In the work by Dizaj et al [18], the spatial variability of pitting corrosion and the record-to-record variability on the seismic vulnerability of RC frames were investigated. Moreover, Dizaj et al [19] described the effects of chloride-induced corrosion in terms of mass loss percentage when the studied frame structure was subjected to mainshockaftershock sequences. Guidelines for modeling the effects of reinforcement corrosion on the mechanical properties of steel and concrete were provided by Dizaj et al [20].…”

Seismic vulnerability analysis of irregular multi-span concrete bridges with different corrosion damage scenarios

“…To this end, it is assumed that the bridge is in the status of 5 years after corrosion initiation (t=5 years), where using Eq. ( 5), the mass loss ratio of longitudinal and spiral reinforcement is calculated as 5.5% and 15.8%, respectively that can be considered as a slight corrosion level according to previous studies of the authors of the current paper [44]. In scenario 3, the bridge piers are considered to be in a long-time exposure to a corrosive environment, where 30 years have passed since the onset of reinforcement corrosion (t=30 years).…”

Reliability analysis of an inter-story isolated structure under a main-aftershock sequence based on the Laplace asymptotic method

“…The building model has a higher probability of overrun after considering the correlation of the two indices. Afsar Dizaj et al (2021) studied the vulnerability of aging concrete frames under the action of main-aftershocks by quantifying the damage state of corrosion variables. The PGA ratio of aftershocks to mainshocks played a key role in the assessment of the seismic vulnerability of aging in highly corroded RC frames.…”