Seismic Response of Beam-End Hinged Self-Centering Frame Structure with Isolated Stairs

To assess the performance of isolated stairs in self-centering frame structures, the controlled rocking reinforced concrete frame (CR-RCF) was selected for analysis. A finite element model of a four-story self-centering frame structure was established, and stairs with different configurations were incorporated to compare and analyze the dynamic responses of four models under frequent and rare earthquakes. The findings reveal that under frequent earthquakes, compared to the fixed staircase model, the maximum inter-story drift ratios of the sliding stairs and rubber-isolated stairs are approximately twice that of fixed stairs, while the base shear forces are reduced by 37% and 43%, respectively. Under rare earthquakes, the base shear reductions of the two types of isolated stairs reduce 45% and 34%, indicating their effectiveness in reducing the structural seismic dynamic response of the structure. Additionally, under rare earthquakes, the inter-story drift ratios of sliding stairs and rubber-isolated stairs can reach up to 3.8 and 3.47 times that of fixed stairs on the same floor, respectively. However, the maximum sliding displacement remains below the design limit, verifying their safety and reliability under extreme seismic conditions. This research offers an initial investigation into stair selection in self-centering frame structures and confirms that rubber-isolated stairs and sliding stairs are well-suited to self-centering frame structures, effectively protecting the main structure from severe damage and thereby enhancing the overall seismic performance and safety of the building. Therefore, it is recommended that rubber-isolated stairs or sliding stairs be given priority in the design of self-centering frame structures to improve the seismic safety level of the structure.