Experimental parametric analysis and numerical simulation of ultra-high-performance concrete beams with microfibers

Ultra-high-performance concrete (UHPC) is a new generation of cementitious material with exceptional mechanical properties. In this study, the effects of type and contents of different microfibers on the mechanical performance of reinforced concrete beams were determined using finite-element (FE) analysis with Abaqus software. The cross-sectional stresses and deflections of UHPC beams containing aramid, basalt, and steel (contents of 1% and 2% by volume) microfibers were assessed. The parametric data of the FE model were defined on the basis of experimentally evaluated results of small-scale specimens. The compressive and tensile strengths of the fiber-reinforced UHPCs were determined. Although the small-scale results indicated an improvement in the tensile behavior of the UHPC and a negligible influence of fiber content on the compressive behavior, the numerical results showed that the use of fibers had no significant effect on the mechanical behavior of the beams (i.e. at ultimate state). The fibers increased the elastic performance of the beams but had little effect on their plastic behavior. Except for the incorporation of 2% steel fibers, the mechanical capacities of the UHPC beams were reduced.