Experimental Research On Intelligent Self-monitoring And Self-repairing Of Concrete Beam With SMA

In this paper, according to cracks injury in actual project, which may make the bridge been inappropriate use ,a self-monitoring, self-repair smart concrete girder bridge structure predigest model, which, in the concrete beams along the length of the beam SMA(shape memory alloys) is embedded into, has been designed. By experiment, the feasibility that SMA as a sensor and drive components for structural health monitoring was verified. In the series of experiment: first, the basic characteristics of SMA, such as the changes of temperature mechanical property, the mechanical property with the strain amplitude changes ,alloy resistance the mechanical property and alloy temperature property was measured; secondly, using the common software Ansys to simulate and control process of the SMA concrete beam deformation, provided a theoretical basis; finally, the test of self-monitoring and self-repair in SMA composite concrete beam was done intelligently. In martensitic state, SMA with plastic deformation becausing of being pre-stressed, was embedded in the concrete beams. There were external two circuits for test model. One was for mensurating resistance; the other was incentive circuit, which can heat up alloy wire. The second circuit mensurate the change of SMA resistances in the course of structural deformation at real time. The relationship between the structural deformation of concrete beam and change of the SMA resistance was simulated and analyse when structural was metamorphosing. Curve relationship between crack width of beam changes and changes rate of SMA resistance have been fitted. The changes of SMA resistance was used to achieve real-time monitoring of injury in the concrete beams. A smart prediction of a concrete bridge in unexpected cracking circumstances was achieved. When, according to the beam embedded forecastly in the SMA implemented the corresponding voltage incentive. With the increase of temperature of alloy wire, martensite phase changed into austenitic phase. At the same time, the state of the plastic deformation disappeared. Under the current, becausing of restore power working to the concrete structure, structure deformation resumed. The self-healing and emergency self-repair of cracks in concrete structure came true.