Flexural Performance of FRP-Reinforced Concrete Beams Using Ultra High Strength Concrete

A Master of Science thesis in Civil Engineering by Zin Subhi Mahaini entitled, “Flexural Performance of FRP-Reinforced Concrete Beams Using Ultra High Strength Concrete”, submitted in April 2022. Thesis advisor is Dr. Farid Abed. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).

Abstract

This research investigated the flexural performance of beams reinforced with fiber reinforced polymer (FRP) bars and cast using Ultra High Strength Concrete (UHSC) with a nominal compressive strength of 140 MPa. A total of fifteen beams were prepared and tested in a four-point loading setup. Ten specimens were reinforced with Glass FRP (GFRP) bars and two specimens were reinforced with Basalt FRP (BFRP) bars. The other three beams were reinforced with conventional steel as reference specimens. The FRP reinforced beams were designed to have either tension-controlled or compression-controlled modes of failure to examine the different responses between them. All beams had 185 mm width, 250 mm depth, and 2200 mm total span length. The influence of different variables including reinforcement ratio, number of longitudinal bars, and reinforcement type was investigated in terms of strain values, midspan deflections, flexural capacities, and cracking responses. The test results showed that the over-reinforced FRP-UHSC beams displayed acceptable deflections at service loads and had adequate ductility prior to failure. Results also showed that the use of GFRP bars in UHSC beams increased the flexural capacity up to 70.15% compared to steel reinforced beams. The BFRP bars were also found to be valuable alternatives to GFRP bars in flexural members. In addition, the analytical predictions compared well with the experimental values of cracking moments and flexural capacities. However, the ACI 440 and CAN/CSA S806 approaches for calculating midspan deflections underestimated the deflections, especially for over-reinforced FRP-UHSC beams.