Experimental and Analytical Study of Ultrahigh-Performance Fiber-Reinforced Concrete Curved Beams

Abstract

This paper presents experimental and analytical investigations on the structural behavior of horizontally curved ultrahigh-performance fiber-reinforced concrete (UHPFRC) beams subjected to concentrated loads applied normal to plane of the beam. Four fixed-ends supported UHPFRC beams with curvatures of 0°, 60°, 90°, and 120° were tested. The structural responses, including the deflection, out-of-plane rotation, and reaction forces of UHPFRC curved beams under all stages of loadings, were experimentally studied. A change in failure mechanism of a UHPFRC beam with the change in its curvature was observed, and the load-carrying capacity and ductility of a UHPFRC beam decreased slightly with an increase in the curvature of the beam. The experimental results also indicated that due to the strain-hardening behavior of UHPFRC materials under tension, a UHPFRC curved beam exhibited improved load-carrying capacity and ductility over conventional straight reinforced concrete beams because the ductility index of each of the UHPFRC curved beam tested was over 3. In addition, structural mechanics–based closed-form solutions were developed for horizontally curved UHPFRC beams using Castigliano’s second theorem to predict the values of bending moment, shear force, reaction force, and torsional moment of the beams under linear-elastic material conditions. Influence lines for bending moment, shear force, and torsional moment were also generated using the validated closed-form equations to show the influences of critical factors on the behavior of UHPFRC curved beams.