Fatigue behavior, damage evolution and enhancement mechanism of RC beams retrofitted with ambient-cured UHPC and steel wire mesh

Abstract

As concrete structures age, the demand for maintenance operations escalates. This study investigates reinforced concrete (RC) beams retrofitted with ambient-cured ultra-high performance concrete (ACUHPC) build-in with embedded steel wire mesh (SWM) to delay crack initiation and propagation. The constant-amplitude sinusoidal cyclic loads experiments for ACUHPC-SWM retrofitted RC beams were conducted to investigate fatigue performance. The results demonstrated that, at the same fatigue stress level, the retrofitted beam achieved a fatigue life in excessing of 2,000,000 cycles compared with the 475,235 cycles for the non-retrofitted beam, while exhibiting reductions of 62.73 % and 68.40 % in maximum and residual deflections, respectively; the retrofitted beam exhibited a 144.6 % increase in initial stiffness. Moreover, the retrofitted beam also maintained 83 % stiffness compared with the initial stiffness. In addition, compared with the retrofitted beam under static load, the retrofitted beam yielded minimal reductions of 1.80 % and 1.61 % in ultimate and yield loads, respectively, after 2,000,000 fatigue cycles conducted under static load conditions. The retrofitting layer can delay crack initiation and propagation, and enhance beams’ initial stiffness and stiffness retention, thereby improving fatigue performance.