Behaviour of carbon fiber reinforced polymer strengthened and retrofitted RC beams

Abstract

This paper deals with an experimental investigation on self-compacting concrete (SCC) reinforced concrete beams of size 150x150x700mm with externally bonded carbon fiber reinforced polymer (CFRP) composites for flexural and shear strengthening. In general, strengthening techniques aims to improve load carrying capacity. Mix proportion for M30 grade concrete was arrived by Nan Su method. The strengthening techniques included are of four types such as Beam strengthened at tension face (BST), Beam strengthened at tension face extending to half depth on two sides of the beam (BSHU), Beam strengthened with four numbers of U-strips (BSUS) and Beam strengthened with two number of U-strips with CFRP inserted in hole (BSUR). Further the failed control beams were retrofitted by similar application as adopted for strengthening and were tested for load–deflection behaviour. The results indicate that among the four configurations, the beam strengthened at tension face (BST) has better flexural response compared with beam strengthened at tension face and extended to half depth at two sides of beams. Beam strengthened with 50 mm wide U-strips with CFRP inserted in a hole exhibited significant increase in toughness. Correlation equations have been developed by using regression analysis and coefficient of correlation obtained are in the range of 0.98 to 0.99 for various applications.