Test and Analysis of Postfire Fatigue Performance of Steel Wires and Cables

Abstract

Fire is an accidental, severe hazard for bridges during their lifetime. Hangers in suspension bridges are among the most vulnerable components with respect to the hanger fatigue effect, and fatigue performance after fire exposure is vital to bridge safety. Therefore, a comprehensive assessment of the postfire hanger fatigue property is necessary. In this study, fatigue tests were conducted on steel wires after various elevated temperatures, and a multiparameter Weibull model was adopted to describe the fatigue data. Based on the fatigue life distribution of steel wires and the corresponding parallel systems, the hanger fatigue life was evaluated using the Monte Carlo simulation and order statistics approach, and the S–N curves were obtained. The results demonstrated that the fatigue life of the hanger was significantly lower than the mean life of the individual wires, and degraded as the exposure temperature increased. In addition, two small cables consisting of 19 parallel steel wires were tested for verification, and the results were consistent with those of the analytical model. The results of this study can be applied to quantify the extent of damage caused by fire and to assess the remaining hanger service life.