Mesoscale modeling of creep damage behavior of UHPFRC under long-term loading

Ultra high performance fiber reinforced concrete (UHPFRC) demonstrates complex creep and failure mechanisms under long-term loading, posing a challenge to the safety of engineering structures. In this work, a novel computational framework is developed to model the creep damage behavior of UHPFRC. The model considers UHPFRC at the mesoscale, consisting of fibers, mortar, and fiber-matrix interface. The time-dependent constitutive model is used to capture the damage and creep characteristics of concrete mortar. Random distributed fibers are modeled by generating conforming meshes between the fibers and the surrounding mortar. The interfacial bonding and debonding behaviors are described through nonlinear cohesive elements. The proposed model is validated through several numerical simulations of uniaxial creep tests and flexural creep tests. The results show that the developed model can well characterize the time-dependent response of the specimens, which offers promise for the analysis of long-term cracking within UHPFRC structures.