Efficiency of innovative strengthening techniques and anchorage systems using different materials on flexure performance of R.C beams

Abstract

This research offers an experimental program that investigates the flexural performance of strengthened reinforced concrete (RC) beams using various techniques. To delay the onset de-bonding of the strengthening system, the novel anchorage system is proposed and examined. Innovative Externally Bonded in Groove technique (EBIG) was introduced to protect the FRP strips from exposure to vandalism, damage, and temperature. Ten half-scale RC beams were cast, a reference beam in addition to nine RC strengthened beams. Strengthened beams were fortified utilizing either Near Surface Mounted (NSM) system or Externally reinforced Bonded (EB) technique using glass fiber at the bottom face of the strengthened beams, whereas one of those beams was strengthened by Externally Bonded in Groove (EBIG). Five test parameters were considered in this research; the strengthening technique used, type of NSM bars, amount of steel bars used, proposed end anchors of steel bars, and the wrapping configurations. The results included the capacity, first cracking load, deflection at different loading levels, cracking pattern, and mode of failure. The stiffness and ductility of strengthened beams were offered and compared. In comparison to the control beam, the strengthened beams with different systems displayed a gain in capacity that ranged from 42% to 105%. Additionally, results demonstrated the superiority of the NSM as a strengthening technique over any other technique, especially the NSM-steel bar which had an innovative end anchorage. An analytical study was applied using the ACI 440.2R-17 design guidelines to compare with the experimental results, the analytical results showed a good prediction. As well, nonlinear finite element models of the tested beams were created using the ANSYS-V22 to validate the structural behavior of those beams according to their capacities, fracture patterns, and deflection characteristics. A good accord between numerical and experimental results was achieved.