Assessment of the effectiveness of the embedded through-section technique for the shear strengthening of RC beams

Embedded Through-Section (ETS) technique is a relatively recent shear strengthening strategy for reinforced concrete (RC) beams, and consists on opening holes across the depth of the beam’s cross section, with the desired inclinations, where bars are introduced and are bonded to the concrete substrate with adhesive materials. To assess the effectiveness of this technique, a comprehensive experimental program composed of 14 RC beams was carried out, and the obtained results confirm the feasibility of the ETS method and revealed that: (i) inclined ETS strengthening bars were more effective than vertical ETS bars, and the shear capacity of the beams has increased with the decrease of the spacing between bars; (ii) brittle shear failure was converted in ductile flexural failure, and (iii) the contribution of the ETS strengthening bars for the beam shear resistance was limited by the concrete crushing or due to the yielding of the longitudinal reinforcement. The applicability of the ACI 318 (2008) and Eurocode 2 (2004) standard specifications for shear resistance was examined and a good agreement between the experimental and analytical results was obtained.The study reported in this article is part of the research project 'DURCOST', PTDC/ECM/105700/2008, supported by FCT. The authors wish to acknowledge the support provided by the 'Casais', Secil (Unibetao, Braga) and Sika Portugal Companies. The first author acknowledges the National Council for Scientific and Technological Development (CNPq), Brazil, for financial support for scholarship (GDE 200953/2007-9)