Abstract: Dynamic compressive test of concrete performance was conducted on specimens with different sizes (150, 300, 450mm cubes) under different strain rates (10^-5/s, 10^-4/s, 10^-3/s, 10^-2/s). The stress-strain curves and energy absorption characteristics were analysed. Moreover, size effect model of concrete strength in consideration of strain rate effect was established based on Bazant size effect theory. Results suggest that the mechanical properties of concrete display obvious size effect and rate effect; the energy absorption capacity per unit volume of concrete decreases with the increase of specimen size, and when the strain rate is small, the energy absorption capacity increases, but after strain rate exceeds a certain value, the increment of energy absorption capacity is not obvious; the strain softening of concrete intensifies along with the increase of specimen size, and the strain softening after peak depends on the specimen’s geometry size.

Key words: concrete, size effect, rate effect, strain softening, compressive performance, energy absorption characteristic