An Anchorage Technique for Shear Strengthening of RC T-Beams Using NSM-BFRP Bars and BFRP Sheet
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nternational Journal of Concrete Structures and Materials Open Access
RESEARCH
An Anchorage Technique for Shear Strengthening of RC T‑Beams Using NSM‑BFRP Bars and BFRP Sheet Hesham M. Diab1* and Ahmed M. Sayed1,2
Abstract This study presents a detailed experimental program for reinforced concrete T-beams strengthened in shear with near-surface mounted (NSM) basalt fiber-reinforced polymer (BFRP) bars. This paper aims to introduce and evaluate a nonmechanical anchorage technique for shear strengthening using NSM-BFRP bars. T-beams were strengthened using manually manufactured closed or U-shaped hybrid BFRP stirrups (BFRP bars and BFRP sheets). The experimental program was developed to study the effects of these anchorage techniques. The results showed that the shear capacity increased by 8%–46% for beams strengthened with NSM-BFRP bars without anchorage. However, the presence of the proposed anchorage system increased the shear capacity of the strengthened beams by 39.6%–81.6%. Moreover, the maximum strains induced in the BFRP bars ranged from 27 to 59% of their ultimate strains according to the spacing between the NSM and the presence of the anchorage. The proposed anchorage technique prevented the premature debonding of the NSM-BFRP bars. 1 Introduction Fiber-reinforced polymer (FRP) systems have been used worldwide for almost the last three decades and are becoming a widely accepted method for strengthening concrete structure in shear and flexure (Diab et al. 2009; Bilotta et al. 2015; Chen et al. 2018). Various experimental studies have been performed to examine the shear strengthening of concrete members using external bonding (EB) FRP sheets/strips (Kalfat et al. 2013; Shekarchi et al. 2018). However, the use of EB-FRP sheets/strips for strengthening concrete members is not entirely problem-free. The use of near-surface mounted (NSM) fiber-reinforced polymer (FRP) bars is an attractive method for increasing the shear strength of shear-deficient reinforced concrete members. Shear strengthening of *Correspondence: [email protected] 1 Civil Engineering Department, Faculty of Engineering, Assiut University, Assiut, Egypt Full list of author information is available at the end of the article Journal information: ISSN 1976-0485 / eISSN 2234-1315
reinforced concrete (RC) beams using NSM-FRP bars is more efficient than using externally bonding FRP sheets/plates (Rizzo and De Lorenzis 2009; Dias and Barros 2011). NSM-FRP bars/strips are less susceptible to damage from fire or vandalism, as they are embedded in the concrete cover. There are several types of FRP bars in the market, such as carbon (CFRP), glass (GFRP), aramid (AFRP), and basalt (BFRP) bars. Various experimental data are reported in terms of the enhancement in the shear load-carrying capacity for the strengthening of concrete beams using CFRP and GFRP with the NSM technique (Anwarul 2009; Sundarraja and Rajamohan 2009). However, the use of conventional CFRP and GFRP composite materials is hindered due to the high cost of CFRP and the poor creep
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