| Summary: | 博士 === 國立臺灣科技大學 === 建築系 === 95 === Available safety egress time (ASET) is one of the basic assessment criteria in performance-based fire safety design, which will directly determine the success of building fire protection design from the results of evaluation. In general, the ASET in performance-based egress design complies with the critical time for the smoke layer height descending to a certain distance above the floor. Through full scale experiments 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 values, the trend of descending time of smoke layer is close to estimated value when N is equal to 20%. In other words, as the evaluation is determined by “N-Percent Method”, adopting 20% as the N value is suggested. (2) In the compartment fire experiments, the experimental and estimated values of the descending time of smoke layer to 1.8 meter above the floor are approximately the same. (3) Similarly, the corresponding time is close to the one reaching threshold values of smoke particle density, carbon monoxide concentration, heat flux, and temperature produced by the smoke layer within the same experiments. Hence, it is rational to take the time of smoke layer descending to 1.8 meter above the floor as the available safety egress time in compartment fire.
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