A failure analysis study of a prestressed steel cable of a suspension bridge

• A failure analysis study is presented.
• Damage phenomenon characterization occurred in prestressed steel cables of a suspension bridge is discussed.
• Results from fatigue tests and fractographic study allow to the conclusion the main cause of cable failure, which led to a collapse of the bridge.

This paper presents results of a failure analysis study to characterize the damage phenomenon that occurred in prestressed steel cables of a suspension bridge. This study includes: material characterization using chemical, microstructural and hardness analysis; fractographic analysis by scanning electron microscopy (SEM); mechanical tests of the material in static tension; fatigue tests (S–N curves) and fractographic analysis of fatigue fracture surfaces. The fatigue tests were carried out in laboratory air only and in the laboratory air also but after previous exposure in tap water to simulate the working environment of the cables. Fractured surfaces of the rods were of brittle failure type and also of cup and cone type. Due to the characteristics of the work environment (close to a river) stress corrosion was also observed and it is likely oxygen embrittlement was obtained.Results from fatigue tests and fractographic study allow to the conclusion that the main cause of cable failure, which led to a collapse of the bridge, was stress corrosion cracking (SCC).