Using NSM pre-stressed rebars for flexural strengthening of RC beams subjected to constant loading

Abstract

The present study introduces an innovative technique for flexural strengthening of reinforced concrete (RC) beams subjected to constant loading and explores its efficacy through experimental evaluation. The technique involves the application of near-surface mounted (NSM) pre-stressed rebars, which exploits the advantages of both the NSM technique, as an effective one commonly used in strengthening RC beams, and pre-stressing, as an effective technique to eliminate excessive cracking and deformation. The experimental program consists of eight identically reinforced RC beams. Before strengthening, longitudinal grooves are cut out along the tensile face of the specimens in which steel bars are placed and anchored by end plates and an epoxy adhesive. Some of the bars are pre-stressed to a predetermined level using an end bolt and a torque-meter wrench. The test results indicate that the NSM pre-stressed steel rebars lead not only to almost identical amounts of significant increases in the ultimate flexural capacity of RC beams but also to decreased initial cracking and deflection.