Effect of microstructural damage evolution on tensile strength of ultra-high performance concrete: A multiscale numerical scheme

This study aims to investigate the tensile behavior of ultra-high performance concrete (UHPC) using a multiscale modeling approach. A micromechanics-based finite-element method is employed to investigate the evolution of microstructural damage and its effect on the macroscopic tensile strength of UHPC. X-ray computed tomography (CT) techniques are used to create a realistic microstructural geometry, and the cohesive-zone models are adopted to quantify the microcrack growth rate and the overall mechanical properties of UHPC under tension. A stiffness-degradation parameter is introduced to explain the evolution of the material tensile behavior. Satisfactory agreements are achieved between the simulation results and the experimental data from the direct tensile tests. To demonstrate the capability of the proposed multiscale modeling framework, the influences of curing age and freeze–thaw cycles of UHPC materials are further taken into account. The proposed multiscale simulation scheme integrated with the x-ray CT techniques and cohesive-zone model can serve as an effective and reliable method to capture the nonlinear tensile responses of UHPC materials and structures.