Experimental and numerical investigation on low-strength RC beams strengthened with side or bottom near surface mounted FRP rods

This article examines experimentally and numerically the flexural performance of low-strength reinforced concrete (RC) beams strengthened using near-surface mounted (NSM) carbon fibre reinforced polymer (CFRP) rods. Five RC rectangular beams were tested in four-point bending until failure. Four of these beams were strengthened using Bottom NSM (BNSM) or Side NSM (SNSM) rods. The results are discussed in terms of observed damage, load capacity, and midspan deflection. It is shown that the SNSM strengthening solution enhanced the cracking load of the beams by up to 19%. Similarly, the yield and ultimate load-carrying capacities of the strengthened beams increased by up to 31% and 64%, respectively. It is also shown that moment-curvature and FE approaches predict well the deflections of the strengthened RC beams within 20% and 10% of accuracy at failure. The results from nonlinear Finite Element (FE) analyses showed a better agreement with the experimental results up to failure (within a 10% of accuracy). For the beams presented in this study, the crack widths calculated by Eurocode 2 match reasonably well the measured values.