EFFICIENT EVACUATION OF TALL BUILDINGS IN FIRES USING LIFTS

ABSTRACT OF THESIS submitted by: Ian HallFor the Degree of: Masters of PhilosophyAnd entitled: Efficient Evacuation of Tall Buildings in Fires Using LiftsDate of submission: September 2010 The objective of this thesis is a study into the feasibility of lift evacuation within high-rise buildings during a fire, in particular, those buildings used as office accommodation. Lift evacuation has been debated theoretically by a number of researchers. A summary of the main methods of evacuation discussed can be summarised as follows: ? Evacuation from a dedicated refuge floor? Evacuation from an occupied floor, which is within a zone of floors provided with lift evacuation.Whilst some researchers have sought to assess the suitability of these methods by conducting simulations and devising calculations to determine the evacuation time from a building, there is limited information available with regards to the assumptions made in these assessments to allow the reader to determine its applicability. Furthermore, the assessments noted above focus on a single method of evacuation and do not compare the different evacuation strategies available. The aim of this thesis is to compare evacuation times achieved in a theoretic building which is designed in accordance with current design codes (i.e. Approved Document B), with those achieved when the building is provided with either of the lift evacuation methods discussed above. This will allow the most efficient evacuation time to be determined. Based on the simulations conducted as part of this thesis it can be demonstrated that the simultaneous evacuation of a high rise office building may be achieved in less time when occupants escape via code compliant stairs designed for phased evacuation rather than using lifts provided in accordance with current design guidance to evacuate. However, these simulations also demonstrate that once the percentage of occupants using the lifts for evacuation decreases, or the lift performance values are increased, the evacuation time from a number of refuge floors or evacuation zones is less than the evacuation time achieved using code complaint stairs. Based on the findings of this assessment, it was considered necessary to develop a programme for preliminary design which is capable of determining if the use of lifts for evacuation is more efficient than a code compliant design, and which evacuation strategy is the most effective.