Investigation of the shear behavior of rectangular cross section RC beams with transverse glass fiber reinforced polymer bars

Over time in the construction sector, steel reinforcement which are used in RC structures for various reasons is subject to corrosion. A reduction of rebars cross-section, deterioration of concrete cover, loss of adherence and change in steel rebars' mechanical properties occur as a result of corrosion. Various protection methods are used to prevent corrosion of the reinforcement rebars. However, none of them sufficiently solve the corrosion's problem. In addition, it is a time consuming and serious economic problem to repair damages in RC structures which caused by corrosion. The progressing of construction sector in parallel with technological developments leads to use GFRP composites as rebars in RC structures which would remove the problem of corrosion permanently and provide longer-life alternative construction. In this thesis, experimental study was conducted on the use of GFRP composites as shear reinforcement (Stirrups) in RC beams. The beam specimens with GFRP stirrups had a rectangular cross-section 150×250 mm, overall length of 1900 mm and were produced under laboratory conditions. Concrete class C25/30 (Commonly used today) and stirrups with ribbed or ribbed-sandy surface were used in the study. The principal variables of this experimental study were stirrups spacing and their surface properties. Beam specimens were designed to have low shear and strong bending strength. Three beam samples were tested for each parameter. Beam specimens were subjected to four-point bending experiment with constant speed loading. Average shear strength, deflection capacities, shear cracks' opening values that formed on the surface of beam specimens were assessed in details. In addition, the experimental results were performed with comparative analysis according the commonly used models in the calculation of FRP reinforced beams and the equations suggested by some researchers which studied in the theoretical part. According to the experimental study findings, GFRP stirrups were found to be effective in shear reinforcement. As well as the beams with ribbed-sandy surface stirrups provided better adherence with concrete and increased the shear strength by 10% comparing to beams with just ribbed (non-sanded) GFRP stirrups. According to the comparative analysis of the shear strength of GFRP-beam obtained from the experimental study with the shear theoretical calculation results of the models and proposed equations, it was found that the equations proposed by the Canadian Standards Association ‶CAN/CSA S806-12″ modul had proposed the most appropriate results.