Seismic performance impacts of staircases in reinforced concrete frame structures under rarely occurred earthquake

Existing research data has been confirmed that the impact of stairs on the overall structure cannot be ignored under the action of earthquakes. To further evaluate the influence of staircases on the seismic resilience of reinforced concrete (Abbreviated as RC) frame structures designed according to Chinese design specifications during infrequent earthquake occurrences, a dynamic elastic-plastic analysis method was utilised. Differences in parameters such as period, vibrational modes, interlayer displacement angle, and base shear force were explored between structures with and without staircases. Data comparisons revealed that, in contrast to frame-only structures, structures with staircases exhibited reduced interstory displacement angles, floor displacement, and floor shear force under lateral loads, with the maximum reduction amplitude being 1.76%, 0.7%, and 1.82%, respectively. Such findings suggest that staircases enhance the lateral stiffness of the structure, thereby bolstering its seismic performance. Furthermore, it was observed that the variance in seismic performance attributed to staircases diminished as the number of storeys increased. The above research results can provide some reference for how to consider the influence of stairs in concrete structures.