Effects of partial shear connection on the strength and ductility of semi-continuous composite steel-concrete beams

Semi-continuous composite beams employ the use of moderate amounts of steel reinforcing over the columns lines in steel framed buildings. These systems have evolved from the development of efficient floor systems in the steel construction industry which ultimately result in reduced structural floor depths. The benefits of this are to the building owner where total construction costs can be reduced and capital and/or leasing costs increased. The U.K. steel construction industry is leading the world in this development by attaining a 60% market share for steel in multi-storey buildings compared with 5-10% in Australia. This paper outlines the results of two full scale experiments on semi-continuous composite beams which are extremely novel in nature. The beams were desigped for full and partial shear connection respectively and, ancillary push tests and material property tests were also carried out. Furthermore, the connections used over the interior support utilised a blind bolting technique in a concrete filled tube which greatly facilitates convenient erection. The exeriments illustrated that the use of partial shear connection resulted in similar ductility of the system when compared with the beam which was designed with full shear connection. Furthermore, both beams illustrated that a plastic mechanism was able to be formed and confirmed that semi continuous composite beams as a design philosophy are able to satisfy the ductility limit state. The experiments are compared with some basic mechanics models to validate the strength and ductility of the system.