Numerical investigation and ANN-based prediction on compressive strength and size effect using the concrete mesoscale concretization model

The concrete mesoscale concretization model (CMCM) is proposed using the statistical distribution and local spatial correlation theory to describe the randomization, continuum, and correlation of the material properties of mesoscale components. The distribution of material properties was obtained by stochastic discretization, spatial correlation correction, and remapping operations. The hypotheses of elastic modulus control (EMC) and characteristic deformation control (CDC) are used to describe the variation of mechanical parameters in the concrete damage plasticity model. The uniaxial compression behavior and size effect of concrete with different side lengths, aspect ratios, aggregate contents, air contents, and contact frictions are simulated using the above model. Without the contact frictions, the size effect of the sample's side length is apparent, while the size effect of aspect ratio is not observed. The increase of size effect degree is contributed by the increase of air content rather than aggregate content. When the loading boundaries are constrained by friction, both the side length and aspect ratio of samples show the size effect. The increase of aggregate content leads to the increase of size effect degree, while the increase of air content leads to a minor increase of size effect degree. The developed CMCM can capture the mechanical responses, and the ANN-based prediction model is applicable to explore the relationship between compressive strength and sample parameters.