Strain rate effect on the fracture parameters of concrete three-point bending beam with a small span-to-height ratio

The fracture properties of concrete are greatly affected by strain rate, and changes in fracture parameters can reflect the crack resistance and failure mechanism of concrete. In this study, fracture tests were carried out on samples of concrete three-point bending beam (TPB) by considering 3 small span-to-height ratios (2, 2.5 and 3) and 4 strain rate grades (10-5/s, 10-4/s, 10-3/s and 10-2/s), in order to examine the strain rate effect on the fracture parameters of TPB. From the test data, the crack propagation rate, fracture toughness, length of fracture process zone (FPZ) and determination of damage scale were calculated. The results showed that the fracture parameters of TPB with a small span-to-height ratio were subjected to an obvious strain rate effect. With the increase of span-to-height ratio, the strain rate effect on the crack propagation rate, fracture toughness and determination of damage scale was gradually weakened, while that on the length of fracture process zone (FPZ) was gradually strengthened. Overall, changes in strain rate can significantly affect the fracture parameters of TPB with a small span-to-height ratio. This paper provides a reference for further research on the strain rate effect and failure mechanism of TPB with a small span-to-height ratio.