Fatigue Performance Of Corroded Steel Bars

Bridges, crane beam, and other reinforced concrete structures are always subjected to various environments and different level cyclic loads. Under the service environments, their internal reinforced steels would be corroded gradually with increasing service time. Under the cyclic loads, cumulative fatigue damage would be cumulated in these steel bars. As a result, the destruction of reinforced concrete member was usually caused by the fatigue fracture of corroded steel bar under the coupling action of environments and cyclic loads.As the corroded steel rebar is the research object in this paper, an accelerating method was adopted to corrode the steel using electricity. To understand the fatigue performance of corroded steel rebar, the following contents are studied:1. On the basis of reverse engineering, a three-dimensional model of corroded steel bar was reconstructed firstly. Then, the morphological characteristics of corrosion were detailed discussed. The results show that the number and the depth of corrosion pit increased with the increase of corrosion rate.2. Axial tensile fatigue test and fatigue fracture analyses of corroded steel rebar were carried out. The research results show that the stress amplitude and the fatigue life of corroded rebar was linearly related in the double logarithmic coordinates, and the corrosion leaded to a significant reduction of fatigue life. The fatigue fracture can be divided into crack source area, crack development area, transition area, and fracture area. Due to the corrosion damage, fatigue crack aurally formed from the corrosion pit in steel rebar, and developed around this zone as a fan shape.3. The magnetic signals were in-time monitored in the fatigue process of steel rebar using a voltage magnetic sensor. On the basis of this test, the relationship between the magnetic signal changes and the fatigue damage were analyzed, and the results revealed that the magnetic signal changes in three phases under cyclic loading, which offered a new method for fatigue fracture alarm.4. Numerical stimulations were conducted to analyze the fatigue performance of corroded steel rebar based on the three-dimensional solid model. The simulated fatigue life of steel rebar agreed well with the test result, validating the numerical stimulation in this study can offer a reference to the fatigue life prediction of corroded steel rebar.