An extended state-based intermediately homogenized peridynamic model for concrete failure analysis considering the ITZ porosity

The interfacial transition zone (ITZ) is inherently a porous region that significantly influences macroscopic mechanical and fracture behaviors of concrete materials. In this study, an extended state-based intermediately homogenized peridynamic model (IH-PD) is proposed for concrete failure analysis considering the ITZ porosity. First, a PD mesoscopic model consisting of mortar and aggregates is established for concrete materials, and the ITZ is implicitly defined by the material interface bonds. An intermediately-homogenized PD model is implemented within the ordinary state-based PD framework, and applied to quantitatively characterize the interfacial porosity. Then, three numerical examples, that is, the wave propagation of a porous glass plate, double cantilever beam test with interfacial porosity, and failure analysis of concrete under uniaxial tension, are investigated for the presented model verification and application. The results indicate that increasing of ITZ porosity leads to a significant reduction in both the responding modulus and critical load. And the cracks primarily propagate along the highly porous ITZ, confirming its role as the weakest link in the mesostructure.