Fatigue-resistant steel bridges

Abstract Inspite of recent efforts to simplify and harmonize guidelines, engineers still have difficulty developing fatigue-resistant bridge designs. Bridges which are subject to fatigue loading need to be designed, fabricated, erected, inspected and maintained according to special criteria in order to ensure sufficient reliability against fatigue failure. The two most important factors affecting fatigue lives of steel bridges are geometry and stress range. Geometrical effects are present through several orders of magnitude. The overall structural configuration is measured in meters, whereas small weld-induced discontinuities are measured in microns. Stress range is directly proportional to the effects of traffic loads and these effects become more predominant when high-strength steels are used. Good fatigue design can have financial benefits when compared to more traditional fatigue checks. Therefore, guidelines are needed in order to encourage consistent and economical designs. Also, more information in areas such as fatigue loading, long-life fatigue strengths and fatigue-strength improvement could lead to further savings.