The low-cycle fatigue behavior tests of nineteen welded Q235 steel I-section bracing members under constant amplitude cyclic axial displacement were carried out, and based on the cyclic numbers of macroscopic crack initiation in the flange monitored, an empirical formula for estimating the low-cycle fatigue life was presented. Based on the test results, the numerical simulation on the hysteretic and the low-cycle fatigue behavior of the bracing members was conducted. The results of analysis and test showed that，the specimens lose their overall stability around the weak axis during the first cycle compression loading, after the third or four cycle, the tensile and the compressive resistances, as well as the single-cycle energy dissipation of the specimens are all gradual decrease. The test and analysis results about the maximum compressive resistance and the maximum lateral deformation of these specimens were investigated and verified in comparison with the results calculated by the relevant literatures or codes. In general, the simulation results agreed well with the test ones. Based on the stress-strain results gained by the numerical analysis, numerical simulation of the low cycle fatigue lives for the bracing members was estimated using two critical plane damage models. It was found that the predicted location of the crack initiation is in accordance with the test results, and the predicted low-cycle fatigue lives basically fall within a safe scatter band of 3.5, moreover, the residual stress has no effect on the low-cycle fatigue life of the bracing members.
