Compressive behavior of UHPFRC under quasi-static and seismic strain rates considering the effect of fiber content

Abstract

The high ductility and toughness of ultra-high performance fiber-reinforced concrete (UHPFRC) make the composite a promising material to be applied in earthquake-resistant structures. For this reason, the knowledge of its constitutive behavior on seismic strain rates (10−2 s−1) becomes of great importance, which was not reported for compressive loading yet. Thus, the purpose of this paper is present experimental results and propose a uniaxial stress-strain equation that predicts the behavior of UHPFRC under compression at seismic strain rate considering different fiber contents. The experimental tests were performed with cylindrical specimens in a servo-hydraulic machine under seismic and quasi-static strain rates for comparison and to determine the dynamic increase factor (DIF). Also, nondestructive tests were performed to determine the dynamic modulus of elasticity. From experiments, UHPFRC was rate sensitive mainly for peak stress and toughness. The DIF observed for peak strength were 1.12 and 1.11 for UHPFRC with 1% and 2.5% of fibers. For toughness, the DIF was 1.21 for the composite with 1.0% of fibers. Peak strain and modulus of elasticity instead were not rate sensitive. Also, high standard deviations characterized the test results. From the analytical study, the proposed constitutive model predicted the dynamic experimental results accurately for different fiber contents.