The Research On Fatigue Similarity Of Reinforced Concrete Beam Based On Piezomagnetism Effect

By the influence of load and environment , the damage of reinforced concrete structure accumulated with the increase of service length, the structural performance was deteriorated. Reload is one important reason which caused fatigue failure of bridge structure. In this paper, the reload fatigue test based on actual vehicle load spectrum was done to research the relation between fatigue reload and structural performance. The main content contained the route of indoor simulation experiment was established by METS method with the technical indicator of piezomagnetic signals, establishing equivalent indoor fatigue load spectrum, the regulation of piezomagnetic signals under fatigue reloading and fatigue life prediction based on piezomagnetic signals. The criterion and detection fatigue damage was stated. The application status of piezomagnetic was introduced. And.On the basis of the statistics of actual vehicle flowrate, the best sample was selected out. Then the equivalent total weight was calculated and used as equivalent fatigue load spectrum. According to the force condition of established bridge model, the actual highway bridge load spectrum was switched to equivalent fatigue load spectrum of laboratory accelerated experiment by the way of equivalent stress.Based on the equivalent fatigue load spectrum, the appropriate amplitude which was applied to the constant amplitude fatigue test of reinforced concrete beam was selected out, and the change rule of piezomagnetic signals during the process was analyzed. The result indicated that the crack propagation of beam determined its failure mode. the crack propagation also affected the fatigue life of beam to a certain degree. The piezomagnetic signals will change abruptly in the section of the shear span. And it will affected the analysis of normal piezomagnetic signals. The change rule of piezomagnetic signals of longitudinal bar and stirrup in the section of the shear span are simulated, and the former is more obvious. The amplitude of piezomagnetic signals in the section of the shear span will became stable after the zooming in initial stage.The feasibility of life prediction by the change rule of piezomagnetic signals based on the test of equivalent load spectrum was analyzed. The predicted result showed that the change rule of piezomagnetic signals could reflected the residual life of beam in a certain extent. However, the more accurate prediction method should be researched further.The research result of this article provided a feasible thought to apply the METS theory to practice and a new method to predict the reinforced concrete structure life.