THE SAFE EVACUATION WITH CONSIDERATION OF THE STOCHASTIC BEHAVIOR OF THE SPREAD PROCESS IN HIGH-RISE BUILDINGS

The blocking time (tn.b = tASET — available safe escape time) is considered as stochastic process. It is necessary for recreation of real stochastic spreading process of dangerous fire factors. The random factors is set as an input data and divided into two groups: the characteristic of fire load and the external environment. The results of numerical modeling of time changestn.b under the possible variation of the liner (Vl ) and mass (b) burnout velocity were presented for assessing the effect of the stochastic behavior of the fire load. The placement of smoke-proof systems, its productivity, and the combined use of smoke exhaust systems and the fire suppression systems were considered as random factors of the external environment. The software “Fire Dynamic Simulation” (FDS) was chosen for the purpose of the spreading process of dangerous fire factors. The simulation of dangerous fire factors was carried out at three stages: within the limits of premises, floor and in a block of floors. The requirements of function parameters of firefighting systems within the limits of premises were determined at the modeling of spreading fire at the first stage that could prevent the fire spread beyond the area of rooms and exhaust the combustion products. The data concerning the series of experiments at the second stage of fire modeling allows determining the required values of function parameters of firefighting systems in order to ensure a required time at each evacuation route segment on a floor. Result of fire modeling at the third stage allows determining that the algorithm of smoke-proof system functioning in smoke-proof stairwells should comply with the algorithm of the evacuation of people from the floors of a high-rise building. In order to decrease the evacuation time and increase the level of people safety in stairwell one needs to organize combined (together with lifts) staged evacuation creating refuges as part of transportation communication network on each floor.