Effects of tensile reinforcing steel ratio and Near-Surface-Mounted bar development length on the structural behavior of strengthened RC beams

Hesham EL-Emam, Alaaeldin El-Sisi, Mohamed Bneni, Seleem S. E. Ahmad, Hossam El-Din M. Sallam
2020 Latin American Journal of Solids and Structures  
The use of near-surface mounted (NSM) Glass fiber reinforced polymer (GFRP) bars is one of the most popular and effective techniques for strengthening reinforced concrete (RC) beams. This paper presents an experimental research program to study the flexural strengthening of RC beams comparing two areas of bottom tensile reinforcing steel and three development lengths of NSM GFRP bars. The beam test results indicated that the beam flexural strength increased up to 110% and 58% for the cases of
more » ... for the cases of low and high tensile reinforcing steel ratios, respectively. The effect of the tensile reinforcing steel area on the critical value of the development length of NSM GFRP bars was also investigated. It was found that decreasing the axial stiffness ratio, reduced the strengthening efficiency and the critical development length of the NSM GFRP bars. Finally, a 3D Finite Element (FE) model using ANSYS was constructed and was validated using the experimental results. Good agreement was seen between experimental and FE model results. Keywords NSM, GFRP rods, flexural strengthening, critical development length, FE analysis Graphical Abstract Effects of tensile reinforcing steel ratio and Near-Surface-Mounted bar development length on the structural behavior of strengthened RC beams Hesham EL-Emam et al. Latin American Journal of Solids and Structures, 2020, 17(6), e295 2/11 Hesham EL-Emam et al. Latin American Journal of Solids and Structures, 2020, 17(6), e295 10/11 CONCLUSION An experimental and numerical investigation was carried out to study the effects of tensile reinforcing steel ratio and the development length of the NSM GFRP bar on the efficiency of the strengthened RC beams. The experimental and numerical results indicate that increasing the GFRP development length changes a beam's mode of failure, giving it greater capacity and more ductility. The load-carrying capacity of a strengthened beam is improved by increasing the NSM GFRP bar development length. The bottom tensile reinforcing steel governs the efficiency of the strengthening by NSM GFRP bars. Decreasing the axial stiffness ratio reduces the strengthening efficiency and the critical development length of the NSM GFRP strengthening bars. Tests demonstrated that beam flexural strength increased up to 110% and 58% for low-tensile and high-tensile reinforcing steel, respectively. The developed FE models were validated using the experimental results and found to be in good agreement with those results.
doi:10.1590/1679-78255836 fatcat:7nv4czlqbrckleuefeutsbhm54