Abstract：This paper presents a study on the histories of ultrasonic velocity variations of concrete specimen during biaxial cyclic compressive loading tests. Results show that the attenuation of the transverse ultrasonic velocity follows S-shape line，which can be divided into three phases，lasting about 10%，80% and 10% of the sample life，respectively. The effects of the level of stress on the sample are investigated，too. A damage variable is defined based on the transverse ultrasonic velocity and used to describe the growth law of fatigue damage. The general method to evaluate the fatigue damage of the concrete and residual life of structure is presented.
