Study on fire smoke control in evacuation passageways on the top floor of an atrium involving breathing zones combined with underfloor makeup air supplementation

Atriums are characterized by the associated large vertically vertical penetrating spaces that provide favourable conditions for smoke diffusion. In case of fire, the main purpose of makeup air and smoke exhaust systems is to ensure the safety of people. Based on the evacuation behaviour of people in fire environments, the concept of available evacuation passageway (AEP) is proposed. Breathing zone combined with underfloor makeup air supplementation is proposed to realise smoke control in AEPs. During a fire, due to the stack effect, the top floor of an atrium is usually most seriously affected by smoke. Therefore, only the smoke control effect on the top floor was analysed. The effects of makeup air inlet layouts and makeup air flow rates on smoke control in an AEP were examined. The results show that when the width of the underfloor makeup air inlet is 0.2 m, the dimensions of the makeup air inlets in the breathing zone are 0.5 m × 1 m (width × height), and the distance between two adjacent makeup air inlets is 1.85 m, the makeup air distribution is most uniform and the smoke control effect is optimal. Under this arrangement of makeup air inlets, when the makeup air flow rate accounts for 90% of the smoke exhaust flow rate, the CO concentration, temperature and visibility in the AEP can all meet the relevant evacuation requirements. © 2022 Elsevier Ltd