Effect of junction stiffness degradation due to fatigue damage of metallic structures

A new method integrating the effect of stiffness degradation is proposed to simulate the performance of a bolted steel joint due to fatigue damage. First, experimental studies are conducted in order to identify a model of junction stiffness degradation and the associated S – N curve. Then, these results are incorporated into a simulation of a portal frame structure to determine the structure’s lifetime, by assuming that fatigue damage occurs only at the junction part, which represents the beam–column connection. Two types of excitation are employed: harmonic loading and narrow band random excitation. Finally, some comparisons between the new proposed method and the classical method are presented.