This paper presents the recent results of an experimental program aimed at disclosing the load- ing rate (loading-point-displacement rate) effect on the crack velocity in high-strength concrete (HSC). Eight- een three-point-bend tests were conducted using either a servo hydraulic machine…
This paper presents the recent results of an experimental program aimed at disclosing the load- ing rate (loading-point-displacement rate) effect on the crack velocity in high-strength concrete (HSC). Eight- een three-point-bend tests were conducted using either a servo hydraulic machine or a self-designed drop- weight impact device. Four strain gauges mounted along the ligament of the specimen were used to measure -4 3 the crack velocity. Six different loading rates were applied, from 10 mm/s to 10 mm/s, i.e., a low loading- -4 2 rate range (5.50×10 mm/s, 0.55 mm/s and 17.4 mm/s) and a high loading-rate range (8.81×10 mm/s, 3 3 1.76×10 mm/s and 2.64×10 mm/s). At low loading rates, the crack propagates with increasing velocity. Un- der high loading rates, the crack propagates with slightly decreasing velocity, though the maximum crack speed reached up to 20.6% of the Rayleigh wave speed of the tested HSC. In addition, the loading-rate effect on crack velocities is pronounced within the low loading rate regime, whereas it is minor under the high load- ing-rate range.