Experimental investigation of high strength reinforced concrete columns damaged by fire and retrofitted with CFRP jackets

Abstract

This paper presents the compressive behaviour of high strength circular reinforced concrete (RC) columns exposed to fire following the ISO834 standard fire curve for 1 or 2 hours, air cooled, and then retrofitted with 2 layers of transverse carbon fibre reinforced polymer (CFRP) wraps. Total 5 circular RC columns ϕ300mm x 1000mm) were tested to investigate the effects of fire duration and the effectiveness of CFRP jackets. The investigated compressive behaviour of columns included load-displacement relationship, CFRP load-strain response and failure mode. Large temperature gradient was observed when columns were exposed to fire. For the unretrofitted columns, the test results showed that the ultimate capacity and stiffness of fire-damaged RC columns was decreased due to the deterioration of concrete at elevated temperatures. Longer fire duration leads to more sever damaged on columns. CFRP jackets could effectively restore the stiffness and improve the ultimate capacity of fire-damaged circular columns.