Influence of inelastic buckling on low-cycle fatigue degradation of reinforcing bars

The effect of inelastic buckling on low-cycle high amplitude fatigue life of reinforcing bars is investigated experimentally. Ninety low-cycle fatigue tests on reinforcing bars varied in amplitudes and buckling lengths are conducted. Using scanning electron microscope the fractography of fractured surfaces are studied. The results show that the inelastic buckling, bar diameter and surface condition are the main parameters affecting the low-cycle fatigue life of reinforcing bars. Through nonlinear regression analyses of the experimental data a new set of empirical equations for fatigue life prediction of reinforcing bars as a function of the buckling length and yield strength are developed. Finally, these empirical models have been implemented into a new phenomenological hysteretic material model for reinforcing bars. The new material model is able to simulate the nonlinear stress-strain behaviour of reinforcing bars with the effect of inelastic buckling and low-cycle fatigue degradation. The results of simulation using the analytical model show a good agreement with the observed experimental results.