Shear performance of reinforced concrete beams strengthened in shear using NSM bars and reinforced HSC layers

• Published in: Structural concrete : journal of the FIB 2023-12, Vol.24 (6), p.7295-7313
• Main Authors: Abdo, Ayman, Sharaky, Ibrahim A., Ahmed, Sayed
• Format: Article
• Language: English
• Subjects: Carbon fiber reinforced plastics; Efficiency; fiber‐reinforced polymer; Finite element method; Glass fiber reinforced plastics; High strength concretes; Mathematical models; near‐surface mounted; Reinforced concrete; reinforced high‐strength concrete layer; Reinforcing steels; Shear; shear strengthening; Stirrups; Strengthening
• ISSN: 1464-4177; 1751-7648
• DOI: 10.1002/suco.202201016

The reinforced concrete (RC) beams could be upgraded in shear using steel and fiber‐reinforced polymer (FRP) having several shapes (bars, strips, or sheets). Using near‐surface mounted (NSM) Glass FRP (GFRP) bars is still limited compared to carbon FRP (CFRP) elements as shear reinforcement. Moreover, using reinforced high‐strength concrete layers (HSCL) as NSM shear strengthening for the RC beams is still limited. Herein, three RC beams internally reinforced in shear using different shear areas (without, 100 mm stirrups apart, and 200 mm stirrups apart) were experimentally tested as reference beams (CB). Other eight beams strengthened in shear using NSM HSCL, and bars were experimentally tested. Moreover, an extended finite element (FE) simulation was implemented through a verified FE model to study the effect of other NSM aspects on shear‐strengthened beam response. The results explained that, regardless of the internal stirrups area and external NSM characteristics, the shear‐strengthened beams showed higher load efficiency than the corresponding CB. The NSM upgraded shear beam had slightly higher load efficiency than the un‐strengthened beam having the same steel area as internally shear stirrups. Moreover, increasing the internal shear stirrups decreased the total efficiency of the NSM shear strengthening and the internal stirrups regardless of the NSM characteristics. Furthermore, the NSM HSCL was more efficient than the corresponding NSM bars in increasing the load capacity and stiffness of the shear‐strengthened beams. The reported analytical model predicted well the shear capacity of the tested beams.