Flexural property and design method evaluation of BFRP and steel bars hybrid reinforced concrete beams

摘要

Fiber reinforced polymer (FRP) bars have been widely used as a replacementfor steel bars in civil engineering due to their high strength and superior durability.However, compared to steel reinforced concrete (RC) beams, FRP RCbeams have insufficient ductility and are more expensive. Therefore, a hybridbeam reinforced with steel and FRP bars has been proposed recently. In thisstudy, the flexural properties of steel bar RC beam, basalt FRP (BFRP) barRC beam, and BFRP steel bars hybrid RC beams were studied based onnumerical simulation. The effect of A_s/A_f on the stress of longitudinal reinforcements,load–midspan curves, ductility, and overall performance of thehybrid RC beams is analyzed. Results indicated that the hybrid RC beamsexhibited a second-order stiffness after the steel bars yielded owing to thecontribution of the BFRP bars. As A_s/A_f increases, the ductility of the hybridRC beam and the strength utilization of BFRP bars increase, and a preferableductility and overall performance can be achieved when A_s/A_f was close to1.0. The theoretical calculation results of hybrid RC beams based on ACI,CSA, and GB codes are compared with the simulation results, and the accuracyof the ultimate flexural strength of the prediction results is verified. Inaddition, equations for predicting the deflection of hybrid RC beams are proposed,and they exhibit higher prediction accuracy compared to the predictionmodels based on the ACI code.