Bending Behavior and Deflection Prediction of High-Strength SFRC Beams under Fatigue Loading

Abstract

The experiments of high-strength steel-fiber-reinforced concrete (SFRC) beams subjected to fatigue bend loading were conducted in this work. A total of 12 beams were tested to failure, including 2 under static loading and 10 under fatigue loading. The main varying parameters of the tested beams included the stress level, fiber volume fraction, and strength of the steel reinforcement. The fatigue life, mid-span deflection, residual deflection, and crack width were measured and evaluated. The stiffness degradation of high-strength SFRC beams was analyzed. The results indicated that both the stress level and fiber volume fraction have significant influences on the fatigue life of the tested beam. The fatigue life of the beams decreased with increasing stress level and increased with fiber volume fraction. With added steel fibers, the stiffness of the beam improved significantly, which leads to the reduced deflection and narrower average crack width during the fatigue loading. The total deflection of high-strength SFRC beam subjected to fatigue loading can be divided into two parts: residual deflections and instantaneous deflections. Both of them were fitted based on the experimental results. Finally, an analytical method which considers the influences of steel fibers was proposed to predict the mid-span deflections of high-strength SFRC beam at different cycles, which agrees well with the experimental results.