Deterioration law of flexural performance of RC beams with initial cracks under alternating action of salt freeze-thaw cycles and fatigue

Abstract

Reinforced concrete (RC) bridges in cold regions are continuously exposed to the combined challenges of traffic loads, freeze–thaw cycles, and salt corrosion. This research delves into the deterioration mechanics and flexural performance of damaged RC beams when subjected to the dual stresses of salt freeze–thaw cycles (SFTCs) and fatigue loading. We conducted performance degradation tests on cracked RC beams subjected to alternating SFTCs and fatigue loading, followed by evaluations of their residual flexural capacities. In-depth analysis considered the impact of the number of alternating cycles and the initial crack width. The results indicate that the combined effects of alternating SFTCs, fatigue loading, and initial cracks significantly diminish the RC beams' flexural strength. As the number of alternating cycles and the initial crack width increased, there was a notable rise in mass loss, rebar corrosion, and a reduction in residual load carrying capacity and stiffness. Particularly, beams without initial cracks saw a 3.61 % reduction in load carrying capacity and a 24.06 % decrease in stiffness after four alternating cycles. In contrast, beams with an initial crack width of 0.10 mm experienced an 11.15 % decline in load carrying capacity and a 38.38 % drop in stiffness. The study concludes that while the combined effects of fatigue loading, SFTCs, and initial cracks are significant, initial cracks exhibit a more pronounced negative influence on load carrying capacity than on stiffness and ductility.