Abstract
We obtained the corroded steel bars by conducting electrically-accelerated corrosion tests. Then, to investigate the effects of the corrosion ratio and the stress amplitude on the fatigue life, and to further study the damage evolution law under corrosion and fatigue loads, we performed axial fatigue tests on 13 steel bars with various corrosion ratios. The laboratory results show that the fatigue life is logarithmical linear to the stress amplitude, and the increase in corrosion ratio leads to the accelerated decrease in the fatigue life. In addition, the increase in stress amplitude can accelerate the fatigue damage, and further decreases the fatigue life. With the laboratory data, we further established a model to predict the fatigue life of the steel bars with various corrosion ratios. The evolution of the residual strains includes the relatively rapid increase, stable increase and rapid increase stages. Moreover, we developed an evolution equation for the residual strain, and this equation can properly describe the laboratory results. Furthermore, considering the fatigue damage, we proposed a constitutive model to describe the stress-strain curve of the corroded steel bar under static tension. The comparison shows that the calculated stress curves agree well with the laboratory curves.
Highlights
The ingressions of the CO2 and the chloride ion, from the voids of the concrete, frequently decrease the pH value in the reinforced concrete of the bridge, and further damage the passivated film of the steel bars
Zhang [13] and Li [14] found that the increase in corrosion ratio decreases the fatigue strength, the ductility and the fatigue life of the naturally and man-made corroded steel bars
The above studies significantly contribute to understanding the effect of corrosion ratio or fatigue load on the strength, the ductility and the fatigue life of the steel bars
Summary
The ingressions of the CO2 and the chloride ion, from the voids of the concrete, frequently decrease the pH value in the reinforced concrete of the bridge, and further damage the passivated film of the steel bars. Zhang [13] and Li [14] found that the increase in corrosion ratio decreases the fatigue strength, the ductility and the fatigue life of the naturally and man-made corroded steel bars. The above studies significantly contribute to understanding the effect of corrosion ratio or fatigue load on the strength, the ductility and the fatigue life of the steel bars. Zhang [20] conducted fatigue tests and static tension experiments to study the effect of corrosion ratio and fatigue loads on the constitutive law. We conducted electrically-accelerated corrosion tests, axial fatigue tests, and static tension tests to investigate the degeneration features of the fatigue life and the evolution characteristics of the residual strain of the corroded steel bars. The damage variable is defined by using the fatigue residual strain of corroded steel bars, and the stress-strain constitutive relation of steel bars considering the damage variable is established
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