Numerical modeling tensile failure behavior of concrete at mesoscale using extended finite element method

Uniaxial tensile behavior of concrete plays an important role in the behavior of concrete specimens as well as structural elements. A 2D mesoscale analysis is performed to investigate the fracture process of concrete subjected to uniaxial tension by using the extended finite element method. The concrete considered includes the hydrated cement paste, aggregate particles, and the interfacial transition zones. In the cracked domain, to represent the discontinuities of a displacement field, the Heaviside jump function is added to the common finite element approximation for the local enrichment based on the framework of partition of unity. A user-defined subroutine for the extended finite element method is implemented with FORTRAN codes and embedded into the commercial software ABAQUS. The failure process of the L-specimen is studied, and good agreement is obtained between the experimental observation and the present simulation results. Based on the extended finite element method, the fracture process of the concrete under uniaxial tension is investigated subsequently. The influences of aggregate distribution, aggregate size, and aggregate shape as well as the strength of interfacial transition zone on the failure process and the global deformation process of concrete are analyzed. The crack initiation, propagation, and failure mode of concrete specimens are also discussed in detail. The simulation results indicate that the macroscopic mechanical properties of concrete are merely dependent on the aggregate distribution, but dependent on aggregate shape, size, and strength of the interfacial transition zone.