Serviceability evaluation model of SFRC beams reinforced with FRP bars based on deformation control

This research investigated the flexural behavior of steel fiber-reinforced concrete (SFRC) beams reinforced with fiber-reinforced polymer (FRP) bars to promote its application in engineering. Ten beams with widths of 150 mm, heights of 250 mm and lengths of 1800 mm were tested under four-point bending. The experimental parameters included the reinforcement type, steel fiber volume fraction, concrete strength, and longitudinal reinforcement ratio of the FRP bars. Based on the test results, a prediction model was proposed for the balanced reinforcement ratio (ρfb), considering the influence of steel fibers. Deformation prediction equations in the current design codes in the US, China, and Canada were compared based on the experimental results. The increase in the reinforcement ratio (ρf) can improve both the service moment (Ms) and the ultimate moment (Mu). With an increase in ρf/ρfb, the Ms/Mu value decreased for under-reinforcement beams but increased for over-reinforcement beams. Based on the linear regression theory, a new calculation model for the flexural moment utilization efficiency of SFRC beams reinforced with FRP bars in serviceability limit states is established. The ductility indices of all beams are above the minimum limit of 4, as proposed by CSA S6-14.