Seismic performance of novel low-damage stair system: Precast reinforced concrete stair isolated with a sliding joint

Abstract

This research presents a solution that can solve the negative diagonal support effect of the traditional precast reinforced concrete stair with rigid connection (TS) and adverse stress centralization on the fragile reinforced concrete (RC) flight. This innovative low-damage stair system utilizes a sliding joint at the bottom of the precast RC stair (SS). Experimental and numerical investigations were implemented on specimens TS and SS to systematically evaluate the seismic responses of the presented low-damage stair system. Experiment results confirm that specimen SS could effectively eliminate the detrimental diagonal support effect of conventional stair systems and the unexpected overlarge stress concentration of the RC components. Therefore, the RC flight and landing beam of the proposed low-damage stair systems remained undamaged at the inter-story drift ratio up to the final level of 4.00%. Taking advantage of the sliding joint, specimen SS behaves with excellent hysteretic performance and energy dissipation capacity. Furthermore, parametric analysis results reveal that the concrete strength remarkably affects the seismic responses of the innovative stairs, while the impact of the friction factor of the sliding joint on the seismic performance is asymmetric during positive and negative loadings.