A Full Scale Experimental Study on Assessing Factors of Available Safety Egress Time

Abstract

Available safety egress time (ASET) is the basic essessing criteria in performance-based fire safety design, which will directly determine the success of building design from the results of evaluation. In general, the ASET in performance-based egress design complies with the smoke layer height descending to a certain distance above the floor. Through full scale experiment of compartment fire in this study, we demonstrated that (1) the relationships between the predicted descending time of smoke layer by ”Two Zone Model” and the practical descending time of smoke layer by experimental measurements; and (2) the comparisons between the descending time of smoke layer and the threshold values of other correlative influential factors, which serve to analyze and calculate the reasonable descending smoke layer height in egress design. From the experimental results, we also concluded as follows: (1) by comparing the experimental data with the estimated value, the trends of descending time of smoke layer is close to estimated value when N is equal to 20%. When the evaluation is by ”N-Percent Method”, adopting 20% as the N value is suggested. (2) In the compartment fire experiment, the experimental and estimated values of the descending time of smoke layer to 1.8 meter above the floor are approximately the same. (3) In compartment fire experiment, the time of smoke layer descending to 1.8 meter above the floor is close to the time reaching threshold values of smoke particle density, carbon monoxide concentration, heat flux, and temperature produced by the smoke layer within the same experiments.