Effect of beam-column depth ratio on seismic behavior of precast RC column-steel beam joint

To achieve the simultaneous horizontal casting of the joint and column in the factory, the authors proposed a new precast RC column-steel beam (RCS) joint. The overall behavior of the proposed joint has been investigated. However, the effects of various design parameters were unclear. This paper focused on the impact of the beam-column depth ratio on the proposed RCS joints. Three 2/ 3 scale interior RCS joint specimens were designed and tested under cyclic loading. Experimental results showed that the joint shear strength and ductility of the specimen improved as the beamcolumn depth ratio decreased. A large beam-column depth ratio could modify the bond condition of column bars. Moreover, a numerical study was conducted to further investigate the influential mechanism of the beam-column depth ratio. According to the distribution of compressive stress, the concrete strut was activated in the joint. The angle between the strut and the horizontal increased with the beam-column depth ratio, leading to less horizontal component to resist the joint shear force. The joint shear strength tended to be overestimated as the beam-column depth ratio increased by using current design methods. Ignoring the effect of the beam-column depth ratio in the design methods may cause significant errors in predicting the joint shear strength.