Shear connection of a prefabricated lightweight steel-concrete composite flooring system

This research PhD thesis investigates the shear connection behaviours and failure modes of two new connection systems used in a newly proposed fully prefabricated lightweight ultra shallow flooring system. The shear connection systems are different to anything presented up to date in the literature and they serve the purpose of the novel prefabricated slab. Experimental, computational and analytical studies were carried out with the aim of improving and optimising the design details, as well as advancing the method of shear connection systems in the prefabricated ultra shallow slabs. A comprehensive Life Cycle Assessment (LCA) was initially performed, followed by an extensive literature review in order to understand the characteristics of shallow and lightweight steel-concrete composite flooring systems. The LCA study resulted in selecting the materials of the prefabricated ultra shallow flooring system (lightweight concrete and steel), before designing the flooring system. Moreover, analytical LCA and LCC studies were also carried out to examine the ecological impact of the new flooring systems, which were then compared with existing prefabricated shallow flooring systems, such as the hollow core precast slab and Cofradal slab. The prefabricated ultra shallow flooring system proposed in this research was developed by this PhD research programme. It is made of a T-ribbed lightweight concrete floor and C-channel steel edge beams, connected with the use of web-welded shear studs (herein called WWSS), and in some cases, horizontally lying dowels too. Their unique configuration minimises its structural depth and results in ultra-shallow floors (structural depths). Thus, two types of shear connection systems were studied: (a) web-welded shear studs only (WWSS), and (b) web-welded shear studs with dowels (WWSS with dowels). In total, eight (8) full scale push-out tests were conducted in the Heavy Structures Laboratory at the University of Leeds, to examine the load-slip behaviour and longitudinal shear resistance of the two shear connection systems under direct shear force. The failure mechanisms of the two forms of shear connection systems were extensively studied, which led to the development of a design method for calculating the shear capacity. Finite Element Analyses (FEA) of the shear connection systems were then performed, supported by eighty four (84) parametric models to further verify the design method that was previously established. Finally, an accurate and reliable moment resistance design method of the prefabricated ultra shallow flooring system was proposed as a practical outcome of this PhD thesis in accordance with the Eurocode 4 and BS5950 standards.