Fatigue classification of welded joints in orthotropic steel bridge decks

This dissertation presents the research into fatigue classifications of welded joints in orthotropic steel bridge decks. These classifications are needed to calculate the fatigue life of these joints and should be included in the design codes. For years bridge design was mainly based on static loading. Due to the development of modern light weight steel structures and extremely increasing traffic loading fatigue design becomes more and more important. A review of all available data on orthotropic decks and related fatigue test results is included. The majority of the full scale fatigue testing on orthotropic decks has been carried out by members of a European Working Group. The statistical analysis procedure used to derive the weld classes for Eurocode 3 is used to place all of the main joints in the appropriate class, and to rank different designs of each joint. In addition, recommendations are made for both good joint design and those to be avoided. The composite action between the steel deck plate and the surfacing on orthotropic decks is an important aspect of the performance, in particular because the stifness of the combined unit helps to reduce strains in the welded structure as well as in the surfacing, which results in a longer lifetime. Numerical as well as experimental analysis of the stress reduction is reported. Furthermore this dissertation highlights site measurements on existing bridges and shows the development of different wearing course systems.