Semi-rigid partial-strength steel-timber composite (STC) connections with mechanically anchored steel rods

Abstract In steel composite constructions, replacing the concrete slabs with prefabricated timber slabs significantly reduces the embodied energy and carbon footprint and lowers the self-weight of the structure and the size of the columns and footings. Considering the advantages of the light-weight steel-timber composite (STC) floors, this paper presents the results of laboratory experiments conducted on six (STC) beam-to-column subassemblies with double angle web cleats and fin plate (nominally-pinned) connections. Preserving continuity of the slabs across the column increases hogging bending moment resistance and stiffness of the composite beam to column connections. Here, the connection between the timber slabs across the column was provided by threaded rods placed inside the timber slabs and mechanically anchored in the pockets of cementitious grout. The STC subassemblies were subjected to a monotonically increasing push-down load to simulate behaviour of the nominally-pinned beam-to-column connections. The results of laboratory tests revealed that mechanically anchored rods can be used to effectively transfer the tensile force developed in the timber slabs of the STC floors and accordingly enhance the stiffness and hogging bending moment capacity of the simple STC beam-to-column connections. The effect of the number, size, and strength grade of the steel rods on stiffness, strength and ductility of the STC connections were evaluated experimentally and component-based method was employed to develop a simple mechanical model for predicting the bending moment capacity of the STC connections with mechanically anchored rods.