Experimental study on elevator door reopening problems caused by stack induced pressure differences across the elevator door in buildings

Stack-induced pressure differences cause various problems in high-rise buildings. In particular, the reopening problem, which involves difficulty in closing elevator doors, and which arises from large stack-induced pressure differences across the elevator shafts, can be especially troublesome. This paper performs an experimental study that uses a full-scale mock-up to evaluate the effects of pressure differences on the functioning of elevator doors. Pressure distribution measurements were taken and simulations were performed for 25 actual buildings to analyze problems related to pressure differences. The analysis shows that the threshold value for malfunctions is different from the previously suggested threshold of 25 Pa. After a theoretical study on the principles governing the operation of elevator doors in an elevator shaft, experiments were performed with a full-scale mock-up that is capable of simulating four airflow directions associated with the stack effect, the reverse stack effect, and the location of the elevator car at either the uppermost or the lowermost floor. The results of the experiments, which were conducted with various conditions for the direction of the stack effect, location of the elevator car, and door type, show that the reopening problem of elevator doors occurs when there is a pressure difference of approximately 40 Pa. It is observed that the problem of elevator door malfunction is more severe at the lower floors during the heating mode and at the higher floors during the cooling mode.