Many building structures in our life are mainly composed of concrete. Thus, monitoring of the failure of concrete structures is of great significance. We built an experimental system to monitor the magnetic field change upon concrete damage, based on which the magnetic field signal of the concrete failure process was tested. And then the relationships between magnetic induction intensity and load, acoustic emission (AE) were analyzed. The results show that the magnetic field can be produced in the process of concrete failure under load, and the change of magnetic induction intensity is consistent with the load. In the compaction stage, the magnetic induction intensity fluctuates and decreases. In the linear elastic stage, the magnetic induction intensity tends to increase steadily. In the plastic stage, the magnetic induction intensity has a tendency of increasing obviously. In the accelerated failure stage, the magnetic induction intensity increases rapidly. In the postpeak stage, the increase of magnetic induction intensity gradually decreases. There is a good correspondence between magnetic induction intensity and AE. When the magnetic induction intensity increases rapidly, the corresponding AE energy grows suddenly. The average coefficient of the correlation between the magnetic induction intensity and cumulative AE energy is above 0.9, showing a high correlation. This further proves that magnetic field can reflect the deformation and failure state of concrete. In conclusion, using magnetic field signal to evaluate the stability of concrete structure is expected to become a new nondestructive and noncontact monitoring method, which is convenient, fast, and continuous as well.

中文翻译：

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混凝土荷载破坏过程中磁场变化的试验研究

我们生活中的许多建筑结构主要是由混凝土构成的。因此，监测混凝土结构的失效具有重要意义。我们建立了一个实验系统来监测混凝土损坏时的磁场变化，在此基础上测试混凝土破坏过程的磁场信号。然后分析了磁感应强度与负载、声发射（AE）之间的关系。结果表明，在荷载作用下混凝土破坏过程中会产生磁场，磁感应强度的变化与荷载一致。在压实阶段，磁感应强度波动并减小。在线弹性阶段，磁感应强度趋于稳定增加。在塑料阶段，磁感应强度有明显增加的趋势。在加速失效阶段，磁感应强度迅速增加。在峰后阶段，磁感应强度的增加逐渐减小。磁感应强度和AE之间有很好的对应关系。当磁感应强度迅速增加时，相应的AE能量突然增加。磁感应强度与累积AE能量的相关系数平均在0.9以上，显示出较高的相关性。这进一步证明磁场可以反映混凝土的变形和破坏状态。综上所述，利用磁场信号评价混凝土结构的稳定性有望成为一种新型的无损、非接触监测方法，