Determining concrete fracture parameters using three-point bending beams with various specimen spans

The effects of specimen spans on concrete fracture parameters were firstly investigated using three-point bending beams. The calculation formulae of the fracture parameters for specimens with span-depth ratios commonly used in testing were put forward based on linear interpolation method. Six span-depth ratios (2, 2.5, 3, 4, 5 and 6) for concrete specimens were explored. Results show that (1) with the increase of span-depth ratio, the critical effective crack length increased linearly whilst constant initial and unstable fracture toughness were obtained; (2) furthermore, the applicability of the proposed linear interpolation method was verified by the available methods in literatures.