Improvement methodology for de-termining the calculated value of the fire risk in buildings and structures based on stochastic description of determining their processes and trees eventsJournal: Pozharovzryvobezopastnost/Fire and Explosion Safety (Vol.26, No. 1)
Publication Date: 2017-01-25
Authors : Kholshchevnikov V.V. Prisadkov V.I. Kosterin I.V.;
Page : 5-17
Keywords : ;
It was analyzed the current state of methodology for determining the estimated value of fire risk in buildings, structures and fire compartments of different classes of functional fire hazard (Annex to the Order of the Ministry of Emergency Situations of Russia on 30.06.2009 No. 382 as amended on 02.12.2015). It was founded that the main parameters used in the procedure are random variables and functions, describing stochastic processes in nature. In the same procedure there are used deterministic parameters of the calculated values, which can sometimes lead to the actual non-compliance with the normative values of individual fire risk. It is shown that the probability of evacuation, accepted under certain conditions equal to 0.999, shall be provided and calculated taking into account the random nature of the spread of fire hazards and processes evacuation during fires, fire safety characteristics of the system objects. It is proposed to improve the methodology for assessing individual fire risk for public facilities in the following areas: 1) improved methods of structure; 2) consideration of the stochastic nature of the input factors affecting the magnitude of the fire risk; 3) accounting for stochastic processes of evacuation, the emergence and spread of fire hazards in the way of evacuation; 4) extension of the list of input factors that affect the value of fire risk, based on their probability characteristics. In this case the object is given a list of fire scenarios, which is described as an event tree. To simplify accounting stochastic computational variables and processes dynamics hazards of fire and evacuation of magnitude Qv individual fire risk assessment proposed to be carried out in two stages. In the first stage, covering the calculated variants of fire scenarios, the probability of a successful evacuation Ver( tbl > tse + te ), where tbl - while blocking dangerous factors of fire escape routes; tse - the start time of the evacuation; te - time of the evacuation can be carried out Monte Carlo using simulation systems. In the second stage payment identified in the first phase of extreme situations is carried out using the specified models, fully taking into account the specifics of the individual movements of people that make up the flow of evacuees in this building, and possible dynamics of fire hazards taking into account peculiarities of functioning of its engineering systems. The proposals on improvement of individual risk methods allow to increase the reliability and accuracy of the estimates, although stipulate additional requirements in terms of knowledge of random variables of input factors distributions.
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