ASSESSMENT OF THE EFFECTIVENESS OF THE EMBEDDED THROUGH-SECTION TECHNIQUE FOR 1 THE SHEAR STRENGTHENING OF RC BEAMS 2 3 J. A. O. Barros 1 and G. M. Dalfré 2 4 1 Full Prof., ISISE, Dep. of Civil Eng., Univ. of Minho, Azurém, 4810-058 Guimarães, Portugal 5 2 PhD Candidate, ISISE, Dep. of Civil Eng., Univ. of Minho, Azurém, 4810-058 Guimarães, Portugal 6 7 8 Abstract 9 10 Embedded Through-Section (ETS) technique is a relatively recent shear strengthening strategy for reinforced 11 concrete (RC) beams, and consists on opening holes across the depth of the beam’s cross section, with the desired 12 inclinations, where bars are introduced and are bonded to the concrete substrate with adhesive materials. To assess 13 the effectiveness of this technique, a comprehensive experimental program composed of 14 RC beams was carried 14 out, and the obtained results confirm the feasibility of the ETS method and revealed that: (i) inclined ETS 15 strengthening bars were more effective than vertical ETS bars, and the shear capacity of the beams has increased 16 with the decrease of the spacing between bars; (ii) brittle shear failure was converted in ductile flexural failure, and 17 (iii) the contribution of the ETS strengthening bars for the beam shear resistance was limited by the concrete 18 crushing or due to the yielding of the longitudinal reinforcement. The applicability of the ACI 318 (2008) and 19 Eurocode 2 (2004) standard specifications for shear resistance was examined and a good agreement between 20 the experimental and analytical results was obtained. 21 22 1. Introduction 23 24 This paper reports the relevant results obtained from an experimental program carried out to assess the 25 effectiveness of the Embedded Through-Section (ETS) technique for the shear strengthening of RC beams. The 26 ETS shear strengthening concept is schematically represented in Figure 1. According to the this technique, holes 27 are opened across the thickness of the beam’s cross section, with the desired inclinations, and steel or FRP bars are 28 introduced into these holes and bonded to the concrete substrate with adhesive materials. Since the strengthening 29 1 Author to whom the correspondence should be sent (barros@civil.uminho.pt).