Experiments on strengthened concrete beams with hybrid steel-grfp rebars

The corrosion problem occurs due to lack of protection given by the concrete cover. The problem of steel reinforcement corrosion has regularly meant improving the quality of concrete, but this approach has only limited success. The aim of the current work is to study the strengthening of concrete beams by increasing the reinforcement area utilizing GFRP rebars instead of conventional steel. In-house mannfacturing of FRP bars bas been described in this research using locally available glass fiber roving and polyester to produce GFRP reinforcing bars. The produced rebars are used as internal reinforcement in simply reinforced concrete beams. All test beams are reinforced with steel rebars with different reinforcement ratios. The concrete cover of these beams with low reinforcement ratios was removed and the longitudinal steel bars and stirmps were exposed. The added GFRP rebars were fixed either inside or outside the stirmps and a suitable cover was provided. Different materials including high strength concrete, cement mortar and a special type of fibrous mortar known as engineered cemeutitious composite (ECC) mortar were used in casting the cover. Some test beams were designed to fail in shear and were strengthened by adding the extra GFRP bars and bonding extemal GFRP wraps to the beam sides in the shear span. The test beams were 100*150*1050 mm and were tested in flexure under 4-point bending up till failure. The structural behavior was investigated in terms of cracking and ultimate loads, deflections, and cracking patterns