An experimental research on concrete beams embedded with pre-stretch Ni-Ti shape memory alloy(SMA) wires was presented during the martensite phase at room temperature,the relationship between resistance change rate of SMA and crack width of concrete beam was tested and the self-repairing of crack was realized while the SMA was excited,the influence of different pre-stretch and clamp had been taken into account in the experiment.The result shows that the resistance change rate of SMA is sensitive to the chan...