A retrospective survey on elevator evacuation of supertall buildings under fires

摘要

Many supertall buildings up to 500mare constructed in the Far East. Big fires in such tall buildings during office hours are a nightmare to firemen. Lots of combustibles might be stored in crowded offices with glass facades. Big fires in tall buildings have been observed many times all over the world. Evacuation is identified as the key problem. Full evacuation is impossible for supertall buildings, taking over 2 hours even in a normal fire drill with good orders. Refuge floors and staged evacuation might be a solution. However, there are queries on whether refuge floors are safe under big post-flashover fires after the World Trade Center tragedy. Elevators are proposed for selective use in the case of fire for accelerating the evacuation process. Studies on elevator evacuation for tall buildings of normal height started over 20 years ago in North America. Results on smoke movement and its management in tall buildings of normal height, human behavior and orderly evacuation, evacuation times modeling, integration with refuge evacuation, and water damage were reported. None of those works related specifically to supertall buildings under big fires. In fact, the use of elevators is included in the evacuation strategy for several supertall buildings in Hong Kong. The elevator systems, however, are not demonstrated to be safe in a fire, leading to deep concern from local fire authority. There is an urgent need to evaluate performance of such existing elevator systems for emergency evacuation in supertall buildings. Active fire protection systems should be upgraded if necessary. In this article, concerns of elevator evacuation are summarized. Points of consideration in designing safe elevator systems in supertall buildings under big fires will be discussed with reference to the literature works.