Flexural behaviour of concrete beams strengthened with near surface mounted fibre reinforced polymer bars

Abstract

Fibre reinforced polymer (FRP) composite materials have been used as internal and external reinforcement for concrete structures. Flexural strengthening of concrete elements using near surface mounted (NSM)–FRP materials are a promising technology. This research is designed to investigate the behaviour of reinforced concrete beams strengthened in flexure with NSM–FRP bars. A total of 20 reinforced concrete beams were tested. Different parameters including internal steel reinforcement ratio, type of NSM–FRP bars, FRP bar diameter, bonded length, and groove size were investigated in this research. Test results showed that the use of NSM–FRP bars is effective in increasing the flexural capacity of concrete beams. In addition, a nonlinear 3D finite element (FE) analysis was used to numerically simulate the behaviour of the test beams. Comparisons between the FE predictions and experimental results showed very good agreement in terms of the load−deflection and load−strain relationships, ultimate capacities, and modes of failure for the tested beams.

Experimental and analytical investigation into the flexural performance of RC beams with partially and fully bonded NSM FRP bars/strips

“…The results reported in [23] suggested that a bond length greater than 80 times the bar diameter had a significant effect on strengthening the NSM reinforcement. In contrast, according to the results stated in [24], there was only an insignificant increase in the load capacity of the beams strengthened with NSM bars when the bond length exceeded48 times the bar diameter.…”

“…These have shown that the technique is greatly affected by bond behavior mainly depending on FRP properties, groove surface and dimensions, adhesive and concrete properties and the position of the FRP reinforcement. The technique has been used to increase the flexural and shear capacities of concrete members [1,[14][15][16][17][18][19][20][21][22][23][24]. In [22], the effect of filling material, concrete properties and bond length on the flexural behavior of RC beams strengthened by NSM reinforcement under a four-point load test was studied.…”

Flexural behavior of hybrid FRP/steel reinforced concrete beams

“…It is based on gluing FRP bars to the concrete near the external surfaces of the tensile zone by mounting the FRP bars in groves cut in the concrete surface [16,17]. Several experimental investigations have been reported on the bond behavior and flexural strengthening of concrete members with NSM FRP reinforcement [18][19][20][21][22][23][24][25][26][27][28][29]. Most of these studies have shown that the technique is greatly influenced by bond between FRP bars and concrete, mainly depending on FRP properties, groove surface and dimensions, adhesive and concrete properties and the position of the FRP reinforcement [21][22][23][24][25][26][27].…”

Effect of adhesive replacement with cement mortar on NSM strengthened RC Beam

“…Most of experimental study was conducted to investigate the flexural behavior of reinforced concrete beam with NSM-FRP bar (AlMahmoud, Castel, François, & Tourneur, 2009;Badawi & Soudki, 2009;De Lorenzis, Nanni, & Tegola, 2000;El-Hacha & Gaafar, 2011;El-Hacha & Rizkalla, 2004;Soliman, El-Salakawy, & Benmokrane, 2010) or strip (El-Hacha and Rizkalla, 2004). The test results confirm that NSM FRP rods can be used to significantly increase the flexural capacity of RC elements.…”