Shear strengthening of reinforced concrete beams strengthened using embedded through section steel bars

A new shear strengthening technique, designated as embedded through section (ETS), has been developed to retrofit existing reinforced concrete (RC) elements. This technique calls for holes to be drilled through the beam section; then bars of steel or FRP materials are introduced into these holes and bonded with adhesives to the surrounding concrete. When concrete cover has not the bond and strength requisites to guarantee a strengthening effectiveness for the Externally Bonded and Near Surface Mounted techniques, ETS strategy can be a competitive alternative since it mobilizes the beam's concrete core which is, generally, free of damage. To explore the potentialities of the ETS technique for the shear strengthening of RC beams, an experimental program was carried out, composed of RC T-cross section beams shear strengthened by using steel bars. The influence on the shear strengthening efficiency of the inclination and shear strengthening ratio of ETS configurations was evaluated; the study also examined the interaction of ETS bars and existing steel stirrups. An increase of shear capacity up to 109% and 136% in the beams with and without internal stirrups, respectively, was obtained. Inclined ETS bars provided higher increase of shear resistance than vertical ones.