Fatigue life prediction of fiber reinforced concrete under flexural load

This paper presents a semi-analytical method to predict fatigue behavior in flexure of fiber reinforced concrete (FRC) based on the equilibrium of for ce in the critical cracked section. The model relies on the cyclic bridging law, the so-called stress-crack width relationship under cyclic tensile lo ad as the fundamental constitutive relationship in tension. The numerical r esults in terms of fatigue crack length and crack mouth opening displacemen t as a function of load cycles are obtained for given maximum and minimum f lexure load levels. Good correlation between experiments and the model pred ictions is found. Furthermore, the minimum load effect on the fatigue life of beams under bending load, which has been studied experimentally in the p ast, is simulated and a mechanism-based explanation is provided in theory. This basic analysis leads to the conclusion that the fatigue performance in flexure of FRC materials is strongly influenced by the cyclic stress-crack width relationship within the fracture zone. The optimum fatigue behavior of FRC structures in bending can be achieved by optimising the bond propert ies of aggregate-matrix and fiber-matrix interfaces. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.