Effect of Weibull Distributed Pre-movement Time on Evacuation

Abstract

The pre-movement time plays an important role in the calculation of Required Safe Egress Time (RSET). The effect of pre-movement time on evacuation is of great importance to the analysis of occupants' safety in fire egress. In this paper, the evacuation software (FDS+Evac) was used to explore the effect of a mean pre-movement time characterized by Weibull distribution on the evacuation time in a room with one exit. The variation of density and velocity was also considered. The results with Weibull distributed pre-movement time and those with constant pre-movement time were compared. The analysis suggested the following: (1) with the decreasing mean pre-movement time characterized by Weibull distribution, the rate of change for evacuation time is more likely to tend toward constant as a result of queuing time at the exit, and (2) the pre-movement time characterized by Weibull distribution has an advantage compared to a constant value in reality. The pre-movement time characterized by Weibull distribution reflects people's characteristics and distributed response time in a real fire, and the results in this paper shows the Weibull distributed pre-movement time compared to a constant pre-movement time affects the overall evacuation time.