Experimental and analytical investigation on the shear behaviour of a demountable interlocking connection applied in precast floor diaphragms

Traditional web connections in precast floor diaphragms adopt cast-in-situ or field welding techniques, which pose significant challenges for the disassembly and reuse of floor slabs. This paper introduces an innovative demountable interlocking web connection that relies on neither traditional welding nor bolting methods, with greatly improved assembly and disassembly efficiencies. Besides, multiple shear connectors can be installed in one go to reduce installation time compared with bolted connection. To assess the in-plane interaction behaviour between shear connectors and embedded steel plates, as well as to evaluate the reusability of this new web connection, a comprehensive experimental investigation was conducted through monotonic loading tests. Results indicated that the proposed web connection exhibited excellent force transmission capabilities, and effectively transferred shear forces through the deformation of the shear connectors. By using faceplates made of highstrength steel, the shear damage was efficiently limited to the connectors, which can be easily demounted and reinstalled to allow the slab to be reused. Additionally, the results also showed that increasing the number of shear keys did not impair the normalised shear resistance per connector but could greatly improve the installation efficiency. Finite element analysis was carried out to further investigate the parameters that influence the connection performance of the proposed web connection. Design recommendations were proposed based on parametric results to predict the in-plane shear resistance of this innovative demountable interlocking web connection.