Design procedure and seismic risk assessment of a controlled rocking reinforced concrete frame with column-end hinge joint

Abstract

The Controlled Rocking Reinforced Concrete Frame with Column-end hinge joint (CR-RCFC) is a newly developed rocking structural system, which has been proposed in the previous study. In this study, to promote its practical application, a two-stage design procedure for the CF-RCFC structure is proposed. The elastic design stage is the same as that of conventional structures, while the rocking design stage adopts a dual-performance design target based on the earthquake-reduction coefficient and inter-story drift ratio. Consequently, the seismic performance of the designed structure is studied by dynamic time-history analysis and the risk assessment is carried out by structural fragility assessment and site-based seismic hazard analysis. The dynamic time-history analysis results indicate that the acceleration response does not significantly increase as the floor rises, demonstrating that the column-end hinge effectively impedes the upward transmission of acceleration, thereby mitigating the acceleration response of the structural upper part. In the seismic risk assessment, the annual exceedance frequencies for Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP) limit states are determined to be 1.88 × 10⁻³, 5.77 × 10⁻⁴, and 3.46 × 10⁻⁵, respectively. For the IO and LS limit states, the CR-RCFC structure exhibits higher annual exceedance frequencies than the conventional reinforced concrete frame (RCF) structure, whereas for the CP limit state, it shows lower annual exceedance frequencies. It indicates the CR-RCFC structure is particularly effective in reducing collapse risk during severe earthquakes.