Tension-softening behavior of UHPFRC based on fracture energy

Abstract

In this study, a three-point bending test is performed on an ultra-high-performance fiber-reinforced concrete (UHPFRC) to determine its tensile performance based on the volume fraction of steel fibers (vf) and member depth as test variables. Based on the bending test results, the overall tensile behavior (σ-ε relationship) of each specimen is derived from an inverse analysis and optimization using a genetic algorithm, and changes in the behavior are analyzed comprehensively based on key variables. In addition, evaluation factors (η1 and η2) that can quantitatively represent the contribution of steel fibers on the fracture energy of the UHPFRC are proposed based on a comparative analysis between fracture energies calculated using the σ-ε relationship and conventional fracture energies. For specimens in which vf is less than 2%, the fracture energy enhanced by steel fibers decreases as the member depth increases, and the values of the evaluation factors (η1 and η2) are maximum at vf 2.0%