Taken advantages of the characteristics of super-elasticity and restoring forces while the shape memory alloy(SMA) was excited,concrete model beams were established by embedding different pre-stretching length,different pieces of Ni-Ti SMA under martensitic state into the concrete tensile zone before the concrete casted under environmental temperature,the relationship between the resistance rate of SMA and the cracks width of beams was studied under loaded process.The impact of slip and bond between the con...