Experimental study on seismic behavior of a reinforced concrete column-steel beam frame interior joint with various details

A novel reinforced concrete column-steel beam (RCS) frame interior joint with tapered-flange-type details was provided in investigation. Cyclic tests of six specimens were conducted to examine the failure process, failure modes and seismic behavior of the RCS joint with various details. Several indexes such as the capacity, ductility, hysteretic curve, skeleton curve, strength degradation, stiffness degradation and energy dissipation capacity of specimens were analyzed. It is shown that there are two failure modes occur during the test. The local bearing failure occurs in specimen RCSJ1, RCSJ2 and RCSJ4, in which concrete were crushed out in the end of column and in the interior part of joint; the shear failure occurs in the other three joints, in which concrete in the exterior part of joint were also crushed out besides that in local failure. The hysteretic loops of the specimens with local failure take on bow shape, while those of the specimens with shear failure take on inversed S shape. The strength and stiffness degradation of the specimens with local failure is faster than that of the specimens with shear failure. The hybrid frame joint presented in this investigation shows good seismic behavior; proper joint details can enhance the cooperative performance of interior concrete and exterior concrete in joint, and thus can enhance the shear capacity and deformation capacity of joint.