Numerical studies on fire hazards of elevator evacuation in supertall buildings

Long evacuation time is a key fire safety concern for crowded supertall buildings. Elevator evacuation appears to be the only choice but fire safety provisions are not specially designed for the use of elevators. A fire safe elevator system was proposed earlier for supertall buildings by providing elevator accessible on each floor level and passing through the refuge place. The fire hazard associated with this design has been studied numerically through an example building in this paper. Smoke spread to the elevator system was considered in the study. The effect of ventilation of the shaft, stack effect and wind effect on smoke movement were studied by empirical equations in fire engineering and justified by computational fluid dynamics. Different designs of smoke extraction with pressurization system were evaluated by analysing the smoke dispersion and pressure distributions. The effect of fire at different heights on smoke spread was also investigated. Results show that the smoke extraction system can only delay smoke spread to the elevator shaft near the fire source for a short time. The "four-floor approach" pressurization system can confine the smoke in the area of fire floor for a sufficiently long time period for safe evacuation.