Fatigue Behavior of Steel-Fiber-Reinforced Concrete Beams

Structures such as bridges, airport runways, marine installations, and railway tracks are often subjected to cyclic loads. These loads can result in a steady decrease in the stiffness of the structure and cause damage at a micro level that eventually leads to a fatigue failure. With the advent of steel-fiber-reinforced concrete (SFRC), there exist the possibilities of enhancing fatigue performance at the structural level, compared to that of members constructed of conventional concrete. Experimental tests at the materials level reported in literature indicate that steel fibers improve resistance to crack growth, decrease deflections, and increase the fatigue life of plain concrete under cyclic loading. This paper reports the results of an experimental study on the performance of SFRC beams tested in fatigue. Twelve (out of 16) reinforced concrete beams with variable fiber contents were tested under constant amplitude cyclic loading. Four reference beams were tested under static conditions. The steel fibers prolonged the fatigue life in SFRC beams by reducing the stress level in the tensile reinforcement. The SFRC beams also demonstrated smaller deflections and smaller crack widths than that of control specimens.