Experimental and numerical study of the behaviour of heat-damaged RC circular columns confined with CFRP fabric

This paper describes an experimental and numerical study of the behaviour of RC columns, damaged by heating and subsequently wrapped by CFRP. Twenty large-scale (Ø 204. ×. 750. mm) nominally identical reinforced concrete (RC) columns were tested. Six columns were left as reference columns and 14 were heated and cooled down under 30% of maximum load at ambient temperature. Subsequently, 8 were confined with carbon fibre reinforced polymer (CFRP) fabrics. A photogrammetric method using the digital image correlation technique (DICT) was used to measure the strain variation over the surfaces of all columns. The experimental parameters included unheated and heat-damaged columns, level of heat exposure and number of CFRP fabric layers. Finite element analysis (FEA) was conducted using ATENA-GiD software, which is only applicable to RC elements. It was found that the CFRP can significantly increase the strength and ductility of unheated and heat-damaged columns. It was also noted that it is possible to repair or even restore the lost strength of columns damaged by elevated temperature, depending on the performance of the CFRP material. The finite element models (FEMs) were able to reasonably predict the experimental behaviour. The FEMs were used to undertake a parametric study to determine the influence of factors not directly considered by the experimental program.