Abstract

Tests and analyses were performed in this study to assess the flexural strengthening capacity of reinforced concrete (RC) members strengthened by the near surface mounted (NSM) technique, which is drawing attention as an alternative to the carbon fiber reinforced polymer (CFRP) bonding strengthening technique. Four-point bending tests were performed on 14 RC specimens. The test variables such as section geometry (250×400 and 400×200 mm), the compressive strength of concrete (27 and 34 MPa), tensile reinforcing bar ratio (0.43, 0.68, 0.98 and 1.42%), and a number of CFRP strips (one, two and three lines) were considered. Through the testing scenarios, the effect of each test variable on the failure mode and the flexural strengthening capacity of the RC members strengthened by the NSM technique were assessed. The test results show that the RC members strengthened by the NSM technique go to failure as a result of the partial CFRP fracture accompanied by crushing of the concrete in the compression zone, and that the CFRP reinforcement area as well as the section geometry have the greatest effect on the strengthening capacity. In addition, analyses confirm that the flexural strength prediction equation proposed by Yost et al.(2007) and the finite element method (FEM) analysis model proposed in this study appropriately predict the flexural strength and the load-displacement response of the RC members strengthened by the NSM technique, respectively.

Key words: Near surface mounted (NSM) technique, flexural strengthening capacity,carbon fiber reinforced polymer (CFRP) strip, four-point bending test.