基于压磁效应的锈胀开裂混凝土梁疲劳性能试验研究

开展了5根锈胀开裂钢筋混凝土梁疲劳试验并实时记录了梁表面的钢筋压磁信号，研究锈胀开裂混凝土梁的疲劳特性和压磁信号演化规律。结果表明梁疲劳寿命随钢筋锈蚀率增大而急剧减小，梁破坏时混凝土剥落，纵筋发生疲劳断裂；磁信号时变曲线随疲劳进程不断演化，在临近疲劳破坏时曲线形态发生明显畸变，能够反映梁疲劳损伤信息；磁感应强度变化幅值的发展符合三阶段特性，在疲劳初期和破坏前增长明显；磁感应强度变化幅值对钢筋锈蚀敏感，随锈蚀率增加而增大，因此建立了疲劳作用不同阶段磁信号幅值和梁内钢筋锈蚀率的相关关系。

Experimental study on fatigue performance of corroded and cracked concrete beams based on piezomagnetic effect

The fatigue test of 5 corrosion-expansion-cracked reinforced concrete beams was carried out, and the compressive magnetic signal of the steel bar on the beam surface was recorded in real time, and the fatigue characteristics of the rust-expansion-cracked concrete beam and the evolution law of the piezomagnetic signal were studied. The results show that the fatigue life of the beam decreases sharply with the increase of the corrosion rate of the steel bar, the concrete spalls during the beam failures, and the fatigue fracture of the longitudinal bar occurs. The time-varying curve of the magnetic signal evolves continuously with the fatigue process, and the shape of the curve is obviously distorted when the fatigue failure is approaching, which can reflect the fatigue damage information of the beam. The development of the change amplitude of the magnetic induction intensity conforms to the three-stage characteristic, and it increases significantly at the initial stage of fatigue and before the failure. The change amplitude of the magnetic induction intensity is sensitive to the corrosion of steel bars, and increases with the increase of the corrosion rate. The correlation between the amplitude of the magnetic signal and the corrosion rate of steel bars in the beam at different stages of fatigue is established.