A new type of rocking column and its application in RC frame structures

A new type of reinforced concrete (RC) rocking column was investigated in this study. Steel tubes were installed for end protection, and steel angles were used as connectors and energy dissipation devices. The concept of pseudo-plastic hinge was proposed to estimate the rotational deformation of the rocking column. Based on this concept, a new fiber-based numerical model was developed and implemented in the software OpenSEES. The lateral force-displacement hysteretic curves and uplifts of RC rocking columns obtained by numerical simulations showed good agreement with the experimental results. The parametric analysis was conducted to explore the effects of steel angle sizes and axial compression ratio on the seismic performance of RC rocking columns. The results show that the increase in the sizes of the steel angles or axial compression ratio significantly increases the load-bearing capacity of the column. The energy dissipation capacity of RC rocking columns rises with the increase of steel angle sizes. To further investigate the potential application scenarios for the proposed rocking column in RC moment frame structures, three five-story RC frames were designed, including a conventional RC frame, a frame with rocking columns in the first story, and a frame with rocking columns and viscous dampers in the first story. The seismic performance of these frames was investigated through nonlinear time-history analysis. The numerical results indicate that, compared to the conventional RC frame, incorporating rocking columns in the first story significantly reduces the residual deformation of the structure. Furthermore, combining rocking columns with viscous dampers in the first story effectively controls both inter-story drift and acceleration responses of RC frames, particularly under near-field earthquake excitations.