Experimental Research on Bending Fatigue Performance of UHPC-T Beams and Evaluation of Their Residual Bearing Capacity

To study the influence of reinforcement ratio and prestressing tendon on the bending fatigue performance and residual bearing capacity of UHPC-T beams, six UHPC-T beams and two concrete T beams were designed and constructed. Four of the beams were subjected to three-point bending fatigue tests, while the other four beams were subjected to three-point bending static load tests, in order to study the influence of the reinforcement ratio and prestressing tendon on the deflection (residual deflection), strain (residual strain), and residual bearing capacity. The results showed that increasing the reinforcement ratio and adding prestressing force had little effect on the concrete strain of the T beams based on a series of fatigue tests. Increasing the reinforcement ratio could reduce the rebar strain, whereas adding the prestressing tendon did not influence the rebar strain. The residual bearing capacity of the UHPC-T beams with 0.372% and 1.14%, and the prestressed UHPC-T beam decrease by 14.0%, 6.7%, and 16.7% compared to the corresponding static ultimate bearing capacity, respectively. It was indicated that the fatigue load decreased the bearing capacity of UHPC-T beams. The residual bearing capacity of UHPC-T beams gradually increased with the increasing of reinforcement ratio or the material performance, and the corresponding deflection and residual deflection decreased. The prestressing force application significantly improved the residual bearing capacity and mitigated the maximum crack width of UHPC-T beams under fatigue loads.