Effect of GFRP bar length on the flexural behavior of hybrid concrete beams strengthened with NSM bars

Abstract

This project aims to investigate the effect of near-surface-mounted glass fiber reinforced polymer (GFRP) bars strengthening on the flexural behavior of hybrid reinforced concrete beams. Seven beams were made; one of these specimens had no strengthening and is considered as a reference beam. The other models were strengthened using near-surface-mounted GFRP bars at the bottom of beams with different lengths (0.5, 0.75, and 1) of effective span beams and diameters (8 and 12 mm) of GFRP bars. The beam length was 2,200 mm with 150 mm width and 240 mm depth. The flexural reinforcement consists of 2 φ12 steel bars at the tension zone and 2 φ12 at the compression zone for all beams. Furthermore, to resist shear forces, φ12 steel bars were used, distributed along the length of the beams spaced at 125 mm c/c; two-point loads on the beams with 500 mm between them were applied at the mid-span. The investigated characteristics were cracking and failure load, crack width, deflection, and failure patterns. By examining the models, it was found that there is an improvement in failure load range from 11.54 to 53.84% relative to the control.

Keywords

• hybrid concrete
• bar diameter
• near surface
• flexural strength
• glass fiber reinforced polymer (gfrp) bars