Wire fractures in locked coil cables

Abstract

Wire fractures in the main cables of the Lysefjord Suspension Bridge display an approximate linear relationship with time. Uncertainties related to wire fractures in sub-layers, reduction of load-carrying capacity and lifetime, and future development of wire fractures have prompted extensive investigations of the main cables. Failure analyses of fractured Z-wire samples and fracture mechanics analysis concluded that cracks have initiated and propagated from surface imperfections. The potential for hydrogen atom generation and absorption that causes hydrogen-induced cracking is discussed. Hydrogen atoms result from the hot-dip galvanization process, or due to corrosion. Evaluation of remaining load-carrying capacity and the need for strengthening of the main cables are briefly discussed and methods for surveillance of wire fractures are presented.