Axial compressive performance of RC columns strengthened with prestressed CFRP fabric combined with UHPC jacket

Abstract

In this paper, a new method of strengthening RC columns combined with prestressed carbon fiber reinforced polymer (CFRP) fabric and an ultra-high performance concrete (UHPC) jacket is proposed. To study the performance of the new strengthening method, eight concrete columns strengthened with different methods and one unstrengthened column were tested under axial compression. The adopted strengthening methods included: adhesive CFRP fabric, prestressed CFRP fabric, UHPC jacket, adhesive CFRP fabric combined with UHPC jacket, and prestressed CFRP fabric combined with UHPC jacket. The effect of UHPC jacket thickness was also investigated. The results showed that the strengthening methods that utilize combined action of CFRP fabric and a UHPC jacked can substantially improve the load carrying capacity and ductility of RC columns beyond the gains offered by the individual strengthening methods using CFRP fabric or a UHPC jacket. With the increase in UHPC jacket thickness, although the specimen load carrying capacity increased significantly, the failure mode changed. The ductility increased to a lesser extent and even reduced. Strengthening that utilized the combined action effectively improved the utilization of the original column as well as the strengthening materials. Based on theoretical models for confined concrete, a unified formula for predicting the axial load carrying capacity of a strengthened column was proposed.