Fire performance of aged and corroded reinforced concrete columns

Abstract

The existing guidelines for determining the fire ratings of reinforced concrete (RC) columns only take into account undamaged components, without considering any deterioration caused by age or corrosion. An experimental study was conducted to examine the effect of corrosion on the fire performance of RC columns. In this study, six full-scale RC column specimens were cast, corroded, and tested in fire conditions, consisting of two made of normal strength concrete (NSC) and four made of high-strength concrete (HSC). Out of these six, three RC columns (1-NSC and 2-HSC) were corroded using a specifically designed accelerated corrosion setup for a target mass loss of 30 %. After the completion of the accelerated corrosion exposure time, these three corroded column specimens, along with three other non-corroded control column specimens, were tested in a fire furnace, simulating the ISO-834 fire curve. It was found that due to corrosion exposure, the steel reinforcement underwent significant mass loss, and severe corrosion cracks were observed. These cracks were discovered to serve as convenient channels for heat transfer. This facilitated the earlier and more severe spalling of the concrete cover, ultimately leading to premature deterioration in the strength of the corroded RC columns during the fire. Consequently, this contributed to the catastrophic failure of the corroded RC columns, with a significant reduction in fire ratings- 44 % for NSC columns and 40.49 % for HSC columns. This paper also addresses the spalling characteristics of the corroded columns and their structural responses, including axial deformations, lateral deformations, and load variations.