Special joints for aluminium structures: structural response evaluation

The profiles for aluminium structures are usually obtained by means of extrusion process that, as well-known, allows many possibilities of cross-sectional shapes. In particular, extruded shapes can be customized according to the different possible uses by incorporating essential design features, such as stiffener, rib, bulbs, slots and tracks. These features can be exploited to conceive more rational joining systems by providing the cross-section with slots and tracks in which mechanical fasteners can be located. These systems, generally named "special joints", represent a very competitive solutions with respect to conventional joining systems thank to the possibility of easy and rapid execution, treatments and machining reduction. Special joints are mainly employed in complementary building structures, such as façades, support structures for solar panels, doors and windows frames. In the last years, other structural applications like staircases, floors, pedestrian bridge, industrial furniture and shelves have been developed involving special joints. Although special joints are widely used in structural applications, few literature about this topic is available and no clear design rules are provided by the main aluminium structural codes. As an attempt to overcome this lack of information, a research about the mechanical behaviour of special joints was undertaken at University of Naples Federico II with the financially support of METRA S.p.A. This paper presents the main results obtained for "screw port" e "bolt-channel" systems.