Experimental and multi-scale numerical investigation of ultra-high performance fiber reinforced concrete (UHPFRC) with different coarse aggregate content and fiber volume fraction

This study investigates the influence of the coarse aggregate content and steel fiber volume fraction on the mechanical properties of UHPFRC. On the meso-scale, according to Mori-Tanaka homogenization method and progressive damage theory, the equivalent damage constitutive model of UHPFRC composite is established. On the macro-scale, the mesoscopic equivalent properties of UHPFRC material are input into the finite element model corresponding to the test for numerical simulation, and the mesoscopic material properties are coupled with the macroscopic finite element model to study the influence of mesoscopic components of UHPFRC on its macroscopic mechanical properties. The compression, tension and four-point bending numerical simulation results of UHPFRC show that the predicted results of the multi-scale numerical model are in good agreement with the test results. It is also found that with the increase of fiber volume fraction, the compressive strength, tensile strength and four-point bending strength of UHPFRC increase first and then decrease. The improvement effect of coarse aggregate on the properties of UHPFRC is not as obvious as that of fiber, and the increase of fiber volume fraction has a significant enhancement effect on the ductility and post peak toughness of UHPFRC slab.