Cyclic behavior of UHPFRC under compression

The research field of constitutive modeling ultra-high performance fiber reinforced concrete (UHPFRC) is in current development. Few experimental results were reported for the material under uniaxial low-cycle loading, and consequently, there is a gap in constitutive propositions to predict its behavior. Thus, one purpose of this research is to provide experimental results for UHPFRC characterizing damage growth and permanent strains during cyclic compression in low-cycle tests with increasing strain amplitudes. Another purpose is to present a constitutive model to predict this behavior of UHPFRC accounting for fiber content. It is worth noting that the present results are relevant to displacement-controlled tests. Damage occurrence was evidenced in the pre-peak branch, mainly by ultrasonic and acoustic techniques. Post-peak damage growth was determined more consistently by mechanical cyclic loading. Also, a new function was chosen to represent damage evolution since the beginning of the load. From experiments, damage occurred even for low levels of loading and increased at low rates until the peak load. After this stage, a sharp drop in strength was observed that resulted in rapidly increase in damage. Then, the decay stabilized and damage returned to grow at low rates. Furthermore, the developed constitutive model predicted with accuracy the behavior of UHPFRC under low-cycle, deformation controlled cyclic compression accounting for different fiber contents104CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ141993/2014-6; 142179/2015-