Ultra Low Cycle Fatigue Life Prediction ofSteel Moment Connection

Observations after Northridge earthquake have shown that low cyclefatigue causes cracking in steel structural components and thepropagation of crack during the loading can lead to the failure ofmember. Hence, it is critical to investigate the behavior of steelconnections in moment-resisting frames by such a phenomenon andthis earthquake-induced fracture can be regarded as an importantmode of failure. In this paper, life prediction of an I-section beam tobox column is under studied; location of cracking is determined bycyclic void growth model and the crack propagation is simulated up toeventual failure. By performing such an approach for different constantpeak cyclic loading, an equation is proposed for fatigue life predictionof the connection. Result obtained from numerical analysis is in goodagreement with experimental test and the path of cracking in theconnection zone is shown correctly.

Keywords:

Ultra low cycle fatigue , Steel moment connection , Crack propagation , Finite element analysis