Flexural strengthening of RC beams using NSM technique

Abstract

Reinforced Concrete (RC) beam elements use bending action to resist the loads imposed on them. In critical situations, ideally, an RC beam must permit ample time to the occupants to evacuate the structure prior to collapse. Structures become weak over time, owing to environmental action, change in occupancy conditions, excessive loading, etc. An effort has been made here, for flexural strengthening of pre-designed beam element, using NSM technique by adopting three types of bars as variables, and by keeping all other parameters constant. The study includes the use of Extruded Glass Fibre Reinforced Polymer (GFRP) bars, Fe-415 bars, and Pultruded Basalt Fibre Rock Polymer (BFRP) bars for strengthening. End de-bonding was observed in all three cases. However, amongst all three, the best one was selected for end confinement using 50 mm wide CFRP wrap, using U-wrap technique in order to ascertain the performance enhancement. Here, since end confinement played its role, no de-bonding was observed. Conclusions are drawn based on observations pertaining to load, deflection, strain in steel, and compressive strain in concrete and de-bonding.