Syncretic investigation on size effect in fracture behavior of dam concrete with physical experiment and mesoscale simulation

Understanding and predicting mechanical properties in large-scale structures such as dams poses a significant challenge, largely due to the inherent size effect in concrete materials. This study presents a mesoscopic investigation into the size effect on fracture behavior in dam concrete under three-point bending, employing both physical experiments and mesoscale simulation. Meso-structures of dam concrete specimens, including prefabricated cracks, are initially generated using a novel method tailored for three-point bending experiments. Subsequently, model parameters and solver settings for the phase field method are calibrated based on laboratory experiments. The fracture behavior and mechanical response of dam concrete under three-point bending are systematically modeled and analyzed, with different parameters including loading positions, maximum aggregate sizes, crack-height ratios, and specimen dimensions. Furthermore, a significant size effect is observed in both fracture resistance and flexural strength, as evidenced by computational outputs. Three classical models proposed by Bažant, Carpinteri, and Kim are adopted, to capture the influence of different maximum aggregate sizes and crack-height ratios on flexural strength, and a favorable consistency is observed across a range of specimen heights from 80 to 500 mm. The presented computational analysis provides valuable insights for the application of experimental and numerical outputs in practical engineering scenarios.