Investigation of the effect of composite bars on slab behavior

Glass fiber reinforced polymer (GFRP) composites are frequently used in civil engineering applications in recent years. GFRP composites which produced by using glass fiber, epoxy resin and accelerometer have significant advantages such as high strength, lightness and resistant against corrosion. However, GFRP composites are more brittle than steel bars. The aim of this study is to experimentally and numerically investigate the behavior of slabs with different tensile reinforcements and compare the results. 5 slabs are produced in Manisa Celal Bayar University laboratory. 2 slabs called as SS-1 and SS-2 have traditional steel reinforcements. 2 slabs called as GFRPS-1 and GFRPS-2 have only GFRP composites. 1 slabs called as GFRPS-F has both GFRP composites and polypropylene fibers. Polypropylene fibers are added in fresh mixture as 0.5% in volume. Dimensions of slabs are 2000x1200x120 mm. Compressive strength of slabs is about 20 MPa. All tensile bars are 8 mm in diameter and 150 mm in spacing. All slabs are subjected to monotonic increase distributed loading until collapse. As a results of tests, GFRPS-1 and GFRPS-2 have carried higher load than SS-1 and SS-2, but SS-1 and SS-2 have exhibited better ductility than GFRPS-1 and GFRPS-2. Cracks of GFRPS slabs are more and larger than that of SS slabs. Polypropylene fibers have significantly contributed tensile behavior of concrete and GFRPS-F slab has exhibited better ductility and energy dissipation than that of other slabs. Number of cracks of GFRPS-F are fewer than that of other slabs. As a result of the experiments, it was observed that GFRPS-F exhibits elasto-plastic behavior and almost returns to its starting position when the loading was removed. Finally, it can be said that GFRP composite bars can be safely used in field concretes, concrete roads, prefabricated panel walls and slabs.