Incorporation of Fatigue Detail Classification of Steel Bridges into the Minnesota Department of Transportation Database

This report addresses the fatigue and fracture susceptibility of the Minnesota Department of Transportation (Mn/DOT) steel bridge inventory and provides a framework for enumerating fracture and fatigue sensitive details present in steel bridges. It also provides a method for rating the details in terms of their overall frequency and consequence of cracking. The research examines eighteen details identified as possible cracking locations, and a composite rank number is computed based on the details it possesses. The report includes a collection of case studies on cracking due to fatigue and fracture, as well as a timeline of changes to the American Association of State Highway and Transportation Officials Specifications for Highway Bridges and the Minnesota Standard Specifications for Highway Construction. Frequency of occurrence of cracking was defined on the basis of a national survey of state Departments of Transportation, from which the experiences regarding steel bridge cracking were collected from fifteen states. The results are organized in a comprehensive table correlating geometric constraints to rank numbers. The report concludes with a program that calculates a composite rank number for each bridge based upon distribution and rank of the individual details present in the bridge.