Abstract

The near surface mounted (NSM) fiber reinforced polymer (FRP) reinforcement is emerging as a promising alternative strengthening technique to externally bonded reinforcement (EBR) for increasing the load carrying capacity of reinforced concrete (RC) members. NSM FRP technique has several advantages, in comparison with the EBR method, such as reducing the risk of debonding, and a better protection from the external sources of damage. In this research, the performance and effectiveness of the NSM and EBR techniques for the flexural strengthening of RC beams are compared. In order to achieve this objective, six full-scale, RC beams were strengthened with different carbon FRP (CFRP) schemes and tested. Such beams were designed to fail in a flexural mode. Test results indicated that if the same amount of CFRP is used, beams strengthened with NSM strips achieved higher ultimate load than those strengthened with EBR. Such increase in the ultimate load ratio ranged between 12% and 18%. Furthermore, a design approach for computing the moment capacity of RC flexural members strengthened with NSM CFRP strips is developed and presented in this paper.

Abstract

This paper presents the numerical analysis of reinforced concrete beams with rectangular and T sections and of steel–concrete composite beams subjected to high temperatures. To obtain the numerical results, which refer to the moment x curvature relations for different temperatures, as well as the maximum values achieved for the bending moments, it was used the fibers method or fibers model, with the constitutive relations of materials (concrete and steel) defined by the considerations of the EUROCODE 2 part 1.2 and by the ABNT NBR 15200. From the results obtained, which are compared with the responses of analytical expressions defined by ABNT NBR 6118 and by ABNT NBR 8800, it is possible to identify the residual strength of the structure as the fire exposure time increases and also demonstrate the effective reduction of its rigidity.