Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

When it comes to vehicular bridges rehabilitation or replacement, designers hardly think of aluminium as a potential structural material. Still, lightweight, corrosion resistance and lower maintenance costs are some assets that aluminium offers compared to steel or concrete. Also, some cases in North America have proven that the retrofit or replacement of an existing bridge deck by one in aluminium is effective, quick and profitable. This factory-built technology is made of extruded aluminium profiles joined by the friction stir welding (FSW) process, a solid-state joining process for different kinds of metals. Even with higher productivity and better-quality joint obtained with FSW compared to fusion welding processes, it is still barely regulated in fatigue and dynamic behaviour design codes for structural applications. In order to overcome the current situation, the main goal of this project is to develop improved, ''performance-based'' code provisions for the quality control and fatigue design of FSW joints in aluminium bridge decks. This study will contribute to develop fatigue criteria and welding defect tolerances in design codes and regulations for FSW which, hopefully, will be promoting aluminium using in civil engineering. It includes fatigue characterisation of 6061-T651 FSW joints under constant amplitude and simulated in-service loading conditions. So far, ADM Cat. B curve would be a conservative design tool for properly FSW joint, assumed to be submitted to variable amplitude loading. Also, wormhole defect within the joint considerably reduce fatigue life as expected. Furthermore, welding defect will be studied, and tolerances will be established for structural applications.