Flexural behaviour of RC beams strengthened with near-surface-mounted BFRP bars

Abstract

Basalt-fibre-reinforced polymers (BFRPs) are promising economical materials developed in recent years for strengthening or repairing reinforced concrete (RC) structures. The effectiveness of strengthening RC beams with near-surface-mounted (NSM) BFRP reinforcement was investigated in this study. One reference beam and six beams strengthened with NSM BFRP reinforcements were tested under four-point loading. The main test variables were the NSM reinforcement ratio, the tensile reinforcement ratio and the pre-cracking load. The experimental results indicated that, compared with the control beam, both the load-carrying capacity and flexural stiffness of the strengthened concrete beams increased due to use of NSM BFRP bars. For the NSM-strengthened concrete beams, the pre-cracked specimens failed by BFRP bar end cover separation while the directly strengthened specimens (not pre-loaded) were governed by concrete crushing. Analytical models based on the section analysis method were developed to predict the maximum bending moment and ultimate deflection at mid-span of the concrete beams strengthened with NSM BFRP bars. The analytical values of maximum bending moment and ultimate mid-span deflection were in good agreement with the experimental results.