Journal of University of Babylon, Engineering Sciences, Vol.(26), No.(3): 2018. 13 Estimation of Maximum Shear Capacity of RC Deep Beams Strengthened by NSM Steel Bars Hayder Hussain Kammona Abdullah Sikar Hassan Al-Issawi Civil Engineering Dep., University of Kufa [email protected][email protected]AbstractThis work aims to estimate the maximum shear capacity of deep beams RC members strengthened by Near-Surface Mounted (NSM) steel bars. This is done by using an assumed semi-empirical formula that depends on experimental tests. This formula will cover many principal parameters such as shear span to effective depth ratios (a/d), orientation angle of NSM steel bars, concrete compressive strength (f′c), bar’s diameter and their spacing. So, thirteen reinforced concrete deep beams with different (a/d) ratios equals (0.85, 1.136 and 1.42) were tested. These beams are categorized into three groups depending on (a/d) ratio, which contained one unstrengthen beam as a control specimen and others strengthened beams by different schemes of NSM steel bars. A comparison between the calculated and experimental values shows good agreement with high coefficient of determination (R2=95.4%). The proposed formula is also used to estimate shear capacity of some specimens that found in some previous literatures toconfirm the validity of the formula in estimating shear capacity of different cases. Good agreement with low (COV) of the predicted shear capacity with the experimental values that found in literatures was obtained. Keywords: Shear Capacity, RC Deep Beam, Near Surface Mounted, Strengthening, Steel Rebar. a/d ratio(a/d= 0.85, 1.136 and 1.42)COV1. Introduction Shear failure is a critical approach regards to concrete members because of its brittle nature. Conventional method of strengthening include different external bonded system techniques had dominate in shear improvement field for long area. Since the concrete structures had relatively long designed life, the future load demand still increasing and structures efficiency need to meet this new standard. In other cases accident may damage important structural member and innovative repairing techniques must apply to restore original member’sperformance. Meanwhile, errors of design and construction needs urgent strengthening even though before structures using. A strengthening process carried out in case of great performance level needed to reach, which include criteria like load carrying capacity, durability, change of structural function, etc. ( Yanget.al., 2007 ). A general term maintenance cover both strengthening and repairing which becomes a common successful solution for hold on critical structures in service, especially in case of non-economical removing or replacing of infrastructures. Choosing incompetent strengthen process may damage member and worsen its efficiency level. Many
Journal of University of Babylon, Engineering Sciences, Vol.(26), No.(3): 2018.