Experimental assessment of the flexural/shear strengthening effectiveness of new CFRP bars

Abstract

The potential of a new carbon fibre reinforced polymer (CFRP) bar (CutInov) is explored for the simultaneous flexural and shear strengthening of reinforced concrete (RC) beams. This bar has a stick geometric configuration, with one part applied according to the near surface mounted (NSM) technique and the other according to the embedded through section (ETS) technique, both connected with a smooth transition zone. The NSM part aims to increase the flexural capacity of the RC element, whereas the ETS part, inclined at 45° relative to the RC beam’s axis, aims to provide shear strengthening and to avoid premature end debonding and rip-off failure modes to the NSM part. To avoid premature rupture at the transition zone of this bar, CFRP fan-type anchors are applied in the critical regions of the beam. An experimental programme with almost real-scale RC beams was executed, composed of a reference beam (Ref) and two beams strengthened with CutInov bars, one with (3CI_A) and the other without CFRP anchors (3CI). Compared to the Ref beam, the 3CI beam presented an increase of 55%, 71%, and 79% in terms of load at a deflection corresponding to serviceability limit state conditions, load at yield initiation of the flexural steel reinforcement, and maximum load, while 3CI_A have even developed better indicators, 61%, 95%, and 117%, demonstrating the efficiency of the CFRP anchors.