Abstract: When the sunken plaza is only used for evacuation, if the provisions of Article 6.4.12 of the GB 50016-2014， Code for Fire Protection Design of Buildings are implemented, it is often difficult to design because of the horizontal distance requirement of 13 m between the openings and the minimum area requirement of 169 m2 for the sunken plaza. However, there are no other fire protection design requirements for sunken plazas used for evacuation in the current national standards. In response to the chaotic design of sunken plazas and considering the actual engineering design requirements, this paper proposes a fire protection design method for sunken plazas used for evacuation within the current framework of Code for Fire Protection Design of Buildings. It emphasizes that all design requirements for sunken plazas used for evacuation should be based on the size of open-air openings. By using calculations, it links the area of open-air openings in sunken plazas, the width of outdoor staircases, and the calculated clear evacuation widths of each fire compartment leading to these sunken plazas, achieving the goal of quantitatively reducing the evacuation width. Additionally, a brief discussion is provided on the fire protection design of superimposed sunken plazas and sunken plazas shared by subway and commercial areas.

Key words: sunken plaza, personnel evacuation, fire protection design