EXPERIMENTAL INVESTIGATION OF PERIMETER DIAPHRAGM AND INTERNAL PLATE EFFECTS ON HYBRID CONNECTIONS OF STEEL AND CONCRETE STRUCTURAL ELEMENTS

For several years, hybrid structures such as CFT and RCS have been studied and their good performance has been proved. By applying the bene ts of concrete and steel together in hybrid systems, a connection with good performance is achieved. Composite structures have been widely used in the construction of buildings due to their excellent static and earthquake resistant properties, such as high strength, high ductility, and large energy dissi- pation capacity. In this paper, an experimental inves- tigation of the perimeter diaphragm and internal plate e ects on a hybrid connection of steel beam to concrete column has been conducted. So, a concrete connec- tion and three composite connections were constructed and tested under cyclic loading. A concrete connec- tion was the standard reference connection and the fol- lowing three connections were proposed as composite connections of steel beam to concrete column: perime- ter diaphragm and internal plates, perimeter diaphragm and inner shearheads, and post tensioned composite. In all these composite connections, the concrete col- umn in the panel zone has been con ned with a steel sheath. The perimeter diaphragm makes the plastic hinge form at a distance from the connection bay and column edge, and the connection elements remain in an elastic state. The results indicated that compos-ing the connection created an increase in loading ca- pacity and energy dissipation. An increase in the duc- tility of composite connections with the perimeter di- aphragm in comparison with the reference concrete con- nection was also observed. By composing the connec- tion, the maximum strength of specimens with a di- aphragm and internal plates, the connection with di- aphragm and shearheads, and the post tensioned con- nection, in comparison with the reference specimen, was increased 239,389,156 percent, respectively. Also, the ductility increase of specimens with diaphragm and in- ternal plates, and with shearheads, in comparison with the concrete specimen, was 118.25 percent.