SIMULATION OF PEOPLE EVACUATION FOR FIRE RISK ASSESSMENT

Transcription

1 SIMULATION OF PEOPLE EVACUATION FOR FIRE RISK ASSESSMENT PhD A.A. Kosachev, PhD A.V. Karpov, D.V. Ushakov All-Russia Research Institute for Fire Protection(VNIIPO) Russia, Moscow region, Balashikha, VNIIPO, 12; Tel: Fax: Professor V. V. Kholshevnikov, State Moscow University of Civil Engineering, Russia, Moscow, Yaroslavskoe Highway, Russia, Ph.D D. A. Samoshin, Lecturer of Academy of State Fire Service of Russia, , Russia, Moscow, B. Galushkin, 4, The method of an individual fire risk estimation puts into practice the rules of the Federal law of the Russian Federation from July, 22, 2008 N123-FZ Technical order about requirements of fire safety. Necessity of performance of a calculating assessment of individual fire risk is defined according to rules of Technical order about requirements of fire safety. This method should be used at: - Incomplete realization of the obligatory requirements of fire safety prescribed by the legislation and normative documents on fire safety; - Creation of fire protection systems (fire detection, the notification and management of evacuation of people at a fire) with the purpose of protection of people and property against the influence of hazardous factors of a fire and (or) restriction of its consequences; - Compilation of the declaration of fire safety within the framework of realization of measures of fire safety. - A substantiation of the requirements of fire safety by development of special specifications on designing of systems of fire safety for buildings, constructions, structures for which there are no normative requirements. Estimation of fire risk is carried out on the basis of calculation of the effect of fire hazardous factors on people. The system of fire safety of object should provide the value of fire risk which doesn t exceed maximum acceptable value.

2 Basic regulations of the method of fire risk estimation The present method establishes the procedure of calculation of individual fire risk for inhabitant, personnel and visitors of apartments and public buildings. For numerical estimation of individual fire risk is frequency of influence Qв of hazardous factors of fire (HFF) on the person in a building is used. Frequency of influence of HFF is determined for a fire-dangerous situation with the greatest threat for life and health of people which are taking place in a building. The level of a safety of people at fires is acceptable if: where Н Q В normalized individual risk, Q В calculated individual risk. Н QВ Q В (1) Н Q В = 10-6 year -1 ; 2. Settlement individual risk Q в in each building (room) is calculated formula Q в = Q п (1-R ап ) P пp (1 - Р э ) (1 - P п.з ). (2) where Q п frequency of occurrence of a fire in a building within one year is determined on the basis of the statistical data. Р пр probability of presence of people in a building, determined as Р пр = t функц /24, where t функц time of a presence of people at the object in hours. Р э probability of evacuation of people; Р п.з probability of effective work of technical decisions of the fire protection directed on maintenance of safe evacuation of people; R ап probability of effective operation of systems of automatic fire extinguishment. At absence of this systems, is accepted equal to zero, at their presence equal to 0,3. 3. Probability of evacuation Р э expect on dependence 2

3 0,8tбл t р, если t р 0,8t бл t р t нэ; t нэ Рэ 0,999, если t р t нэ 0,8t бл ; (3) 0,000, если t р 0,8t бл ; where t р calculated time of evacuation of people; t н.э time interval from occurrence of a fire to the beginning of evacuation of people. t бл time from the occurrence of a fire to blocking of evacuation ways as a result of spread of combustion products having the values of fire hazardous factors which exceed the maximum acceptable values for people (time of blocking of evacuation ways); 4. Calculated time of people evacuation, t р, from enclosures and buildings is determined by means of modelling of people movement to an exit outside. 5. The value of the time of the evacuation beginning, t нэ, for a n enclosure of fire origin is necessary to accept equal to 0,5 min. For other rooms value of time of the evacuation beginning is defined by the table 1. 3

4 п/п Class of functional fire danger of enclosures and the features of the people inside Table 1 Value of time of the people evacuation beginning t нэ, min. The buildings equipped The buildings which with system of the notification and manage- system of the notifica- are not equipped with ment of people evacuation people tion and management of evacuation 1 Apartment houses of long residing. Inhabitants can be in a condition of dream, but are familiar with structure of evacuation ways and exits (F1.1, F1.3, F1.4) 2 Hotels etc. Inhabitants can be in a condition of dream and are not familiar enough with structure of evacuation ways and exits (F1.2) 3 Entertainment, cultural, educational and serving the population establishments (F2, F3). Visitors are in an awake condition, but can be not familiar with structure of evacuation ways and exits III V type I-II type 4 6,0 9,0 2,0 3,0 6,0 1 3,0 6,0 4 Civil and professional training establishments (F4). Visitors are in an awake condition and are well familiar with structure of evacuation ways and exits 1,5 3,0 6,0 6. Time t бл is determined by calculation of time of achievement of critical values of HFF on the evacuation ways. 7. Probability of effective work of technical decisions of the fire protection Р пз, directed on maintenance of safe evacuation of people is calculated by the formula Р ПЗ R R, (4) СОУЭ ПДЗ 4

5 where R СОУЭ probability of effective operation of system of the notification and management of evacuation at a fire; R ПДЗ probability of effective operation of system of smoke protection; 8. In buildings and constructions with mass stay of people designed for presence of 50 and more persons, in addition to a condition (1) conditions (5) and (6) should be executed: t р +t нэ 0,8 t бл (5) t ск 6 min, (6) where t ск time of existence of congestions of people for sites of a way (the density of a human stream on ways of evacuation exceeds value 0,5 ) Modelling of the process of people evacuation Modelling of the process of people evacuation from a building is carried out by one of the following ways: - by simplified analytical model of movement of a human stream; - by mathematical model of individual - stream movement of people from a building; - by of simulation-stochastic model of movement of human streams. The choice of the appropriate model for determination of calculated time of evacuation is made in view of specific features of space-planning characteristics of a building, and also features of people taking place in a building. At calculations it is also necessary to take into account, that at presence of two or more evacuation exits general transmission capacity of all exits) except each one of them, should provide safe evacuation of all people which are in a enclosure, on a floor or in a building. 5

6 Simplified analytical model of movement of a human stream [9] The basic principle of this method consists in the following. The whole way of movement of a human flow is divided into sites (pass, corridor, door aperture, ladder march, tambour) with length l i and width d i. Initial sites are the passes between workplaces, by lines of armchairs in halls etc. Length and width of each site of a way of evacuation are accepted according to the project and accepted fire scenario. The calculation time of evacuation of the people t p is defined as the sum of time of movement of a human flow on separate sites of a way t i under the formula: t р = t 1 + t 2 + t t i, [s] (7) where t 1 time of movement of a human flow on first (initial) site, s; t 2, t 3,, t i time of movement of a human flow on each of sites of a way following after first, s; The basic structure, which is operated with a technique, is the human flow. The characteristics of a human flow are: density of a human flow (D), speed of movement (V), intensity of movement (q). Calculation with the specified technique allows to determine the time of people movement outside of a building with taking into account the merge of human flows on some sites of a way. The time of movement of a human flow on separate sites of a way defines according to the following dependence: l i ti, [s] (8) Vi where l i length of a site of a way with number i; V i speed of a human flow on the given site. The speed of a human flow V i is defined according to empirical correlations depending on the value of intensity q i, which defines under the formula: q i = (q i-1 d i-1 ) / d i, [m/s] (9) where d i-1 и d i width of sites of a way with numbers i and i-1, m; 6

7 q i-1 и q i intensity of movement of a human flow on sites of a way with numbers i and i-1, m/s. Simulation-stochastic model of movement of human streams Speed of movement of a human stream with density D i on i-th a piece of a site of a k-th kind way is a random variable V D,k, having the following numerical characteristics: Average of distribution V D,k = V 0,k at D i D 0,k, (10) V D,k = V 0,k (1 a k lnd i / D 0,k )m at D i D 0,k ; mean-square deviation σ(v D,k ) = σ(v 0,k ) (1 a k lnd i / D 0,k ), (11) where V 0,k и σ(v 0,k ) Average of distribution of speed of people free movement in a stream (at D i D 0,k ) and its mean-square deviation, m/min; D 0,k limit value of density of a human stream, until which free movement of people is possible on k-th kind way (the density does not influence on speed of people movement); a k factor of adaptation of people to changes of density of a stream at movement on k-th kind way; D i value of density of a human stream on i-м a piece ( l) of a site of a way with width b I, people/m 2 ; m factor of an aperture influence. At any possible value V 0,k people in quantity Ν t0 i, taking place at the moment t 0 on i-th an small site, are moving on it and starting to pass to the subsequent site i+1. To a site i in their turn a part of people passes from the previous (i 1) small site and from the source j, fig. 1. By the time moment t i = t 0 + t only the part of people Ν ti i,i+1 from a site i will pass to a site i+1. From Ν t0 i people, who were on the site i at the moment t 0, Ν t0 i Ν t0 i,i+1 people remain. Their number is supplemented due to people which pass for this 7

8 interval of time from the previous site Ν t0 i 1,i and from source N t0 j,i. Then the density of a stream on a site i at the moment t 1 will be equal D t1 i = Ν t0 i Ν t0 i,i+1 + Ν t0 i 1,i + N t0 j,i / b i l. (12) Speed of people movement of on a site i at the moment t 1, is determined as function of the density of a stream, i. e. V t1 i = V 0,k (1 a k lnd t1 i / D 0,k ). (13) time moment t 0 Момент времени t 0 N i t 0 t t D 0 = N 0 / b l i i i b i - 1 t t 0 0 D D i - 1 i + 1 t t 0 V = ( 0 t D ) 0 t V = ( 0 D ) i - 1 i - 1 i - 1 i - 1 i-1 i + 1 i i+1 i - 1 t t 0 0 Ni + b i + 1 N i l l t t t Nj Dj, Vj = ( Dj ) j bj time moment t i = t 0 + t Момент времени t = t + t 1 0 t t t t t t t D = ( N - N + N + N )/ b l; V = ( D ) A i i i, i + 1 i - 1, i j, i i i B t V, если t D < t t 0 0 t if D V 0, если D 0 i - 1 i q t if < D V 0 i i + 1 max A = t t V 0 V 0, если D 0 > D V A V B = t t B V 0, если D 0 > D i if i q max if i + 1 i + 1 q max q max N i - t C C 0 A B 1, i t 1 Nj,i t t t t N 0 - N 1 = N 0 (1 - V 0 t/ l); i i, i - 1 i B V C t t t t t t N = N V t/ l; N = D b V t i - 1, i i - 1 A j, i j j C t V 0 = C N i, i + 1 Part of flow in congestion on i-th site t t Vj 0, если D 0 < D t t V 0, если D 0 > D Доля участия при образовании скопления на участке i t t t t t t t t N / N = P / P = D V b / D V b i - 1 j i - 1 j i - 1 i - 1 i - 1 j j j i if if i i q max q max Fig. 1. People stream states of in consecutive moments of time t 0 and t 1 = t 0 + t 8

9 Similar process occurs on all elementary sites occupied with human streams. Change of stream density at each site at the various moments of time reflects the process of rearrangement of different parts of a stream in each of them and, as a special case, process of a stream dispersion. Change of density of a stream on each of elementary sites at the consecutive moments of time depends on the amount of people passing through borders of sites. Generally the amount of people passing for an interval of time t from a site i to the subsequent site i+1 Ν t1 i,i+1 = D t0 ib i V пер t, (14) depends on speed of transition V пер through border of site B-B or, accordingly, А-А, С-С. Speed of transition V пер through borders of adjacent elementary sites should be determined as: t0 t0 Vi, если Di 1 D for max ViDk. D qmax Vпер (15) t0 t0 Vi 1, если Di 1 D for max ViDk. D qmax. if V пер = V t0 i, than time t пер., necessary for transition of all Ν t0 i people which are taking place on an elementary site i at the moment t 0, to the subsequent site (i+1), will be : t пер = Δl / V t0 i. (16) For an interval of time Δ t< t пер not all Ν t0 i people will proceed to a site i+1, but only their part Ν t0 i,i+1 = Ν t0 iv t0 i t / Δl. (17) Amount of people, who had no time to proceed for an interval of time Δt from a site i to a site i + 1, hence, will be Ν t0 i Ν t0 i,i+1 = Ν t0 i(1 V t0 iδt / Δl). (18) If V пер = V t0 i+1, the similar correlations will be valid in which instead of V t0 i it is necessary to accept V t0 i+1. Thus the amount of people remaining on a site i, is increasing, and the amount of people passing to it from the previous elementary site i 1 and a source j, remains the same, as at V пер = V t0 i. Hence, the density of a stream on a site i 9

10 at the following moment of time t 1 will be more high, then at V пер = V t0 i. It will increase the faster, than the value V t0 i+1 is lower, i. е. than value D t0 i+1. is higher. At D t0 i+1 = D max this process models the spread of a people congestion. If at any moment of time t п the density of a stream on a site i has reached the maximum value and can t increase further, there no person can come to this site at this moment of time neither from previous site, nor from a source. In result before their borders with a site i ΔN tп i 1 and ΔN tп j,i people are delayed accordingly. At the following moment of time t п+1 the part of people from a site i passes to a site i+1, the density of a human stream on it decreases also and a part of people which have accumulated before its borders can proceed to it. But it is not all people which have accumulated on borders of sites i 1 and j. The part of their participation in supplementation of a site i by people at the moment t п+1 is determined by formula: ΔN tп+1 i 1 / ΔN tп+1 j = D tп+1 i 1V tп+1 i 1b i 1 / D tп+1 jv tп+1 jb j (19) These correlations completely describe a condition of a human stream on elementary sites and their transitions at the consecutive moments of time at fixed values V 0,к, and allow to calculate the appropriate values of time of movement of human streams from sites of their formation to section of a way in which evacuation comes to an end. Set of values t Δ, received at various values V 0,k, forms empirical distribution of probabilities of values t р. This distribution allows to calculate by rules of mathematical statistics value of time of the evacuation end, appropriate to probability Р(t р.эв ) = 0,999. Mathematical model of individual - stream movement of people from a building The calculated time of evacuation of people from a building is determined as a time of a last person from a building. Before the beginning of evacuation process modelling the scheme of evacuation ways in a building is set. All evacuation ways are subdivided on evacuation sites with length a and width b. The length of a way on ladder marches is measured on length of a march. The length of a way in a doorway is accepted equal to zero. Evac- 10

11 uation sites can be horizontal and inclined (a stair downwards, a stair upwards and a ramp). For dimensions of the person in the plan the ellipse with the sizes of axes appropriate to width of the person in shoulders and thickness of the person is accepted. Coordinate of each person x i (distance from the centre of the given person to the end of evacuation site on which he is (see fig. 2)) is set. Coordinates of each person x i at the initial moment of time are set according to the scheme of arrangement of people in enclosures (workplaces, places for spectators, beds etc.). In case of absence of such data, for example for shops, showrooms etc., it is supposed to place people in regular intervals on all area of enclosure with taking into account the arrangement of the process equipment. The coordinate of each person at the moment of time t is determined by the formula: x i (t) = x i (t-δt) V i (t) Δt m, (20) where x i (t-δt) Coordinate of i-th person at the previous moment of time, m; V i (t) speed of i-th person at the time moment t, m/s; Δt time interval, s. 11

12 а Х b Х 1 Х2 Х 3 Х 4 Х 5 Х 6 Х 7 Fig. 2. The coordinate scheme of people arrangement on evacuation ways Х The speed of i-th person at the moment of time t V i (t) is determined by empirical correlations and is depending on local density of a stream in which he goes, D i (t) and on type of evacuation site. Local density D i (t) is calculated for the group consisting from n persons, by the formula: where n amount of people in a group; D i (t) = (n(t)-1) f / (b Δx) m 2 /m 2, (21) f the average area of a horizontal projection of the person, m 2 /m 2 ; b width of evacuation site, m; Δx difference of last and first person in group coordinates, m. 12

13 If at the moment of time t the coordinate of the person x i (t), calculated by the formula (20), becomes negative, it means, that the person has reached the border of the current evacuation site and must pass to the following evacuation site. In this case the coordinate of this person on the following эвакуационном a site is determined as: x i (t) = [x i (t-dt) V i (t) dt] + а j l j m, (22) where x i (t-dt) coordinate of i-th person at the previous moment of time on (j 1)-ом эвакуационном a site, m; V i (t) speed of i-th person on evacuation site (j-1) at the moment of time t, m/s; a j length of j-th evacuation site, m; l j coordinate of a place of merge of j-th and (j-1)-th evacuation sites - distance from the beginning j-го эвакуационного a site up to a place of its merge with (j-1)-th evacuation site, m. The amount of people passing from one evacuation site to another is determined by transmission capacity of an exit from a site Q j (t): Q j (t) = q j (t) c j dt / (f 60) чел, (23) where q j (t) intensity of movement at the outputfrom j-th evacuation site at the moment of time t, m/min; c j width of an exit from j-th evacuation site, m; dt time interval, s; f the average area of a horizontal projection of the person, m 2. Intensity of movement at the exit from j-th evacuation site at the moment of time t is depending on density of a human stream on this site Dv j (t). The density of a human stream on j-th evacuation site at the moment of time t Dv j (t) is determined under the formula: Dv j (t) = (N j f dt) / (a j b j ) m 2 /m 2, (24) where N j number of people on j-th evacuation site; 13

14 f the average area of a horizontal projection of the person, m 2 ; a j length of j-th evacuation site, m; b j width j-th evacuation site, m; dt time interval, s. In fig. 3 the algorithm of determination of calculated evacuation time of people from a building is presented based on the mathematical model of individual - stream movement of people. 14

15 Input of the initial data Definition of people initial coordinates Definition of evacuation site parameters Definition of time of evacuation beginning for each person Determination of people stream densities at evacuation sites Determination of aperture transmission capacity Output of evacuation process features Transition to the next time moment Determination of movement direction for each person Determination of people stream density before each person (distance to person moving ahead) Determination of movement velocity for each person Determination of the coordinate for each person no Is evacuation completed? END yes Fig. 3. Algorithm of evacuation process modelling 15

16 Development of a fire and spread of fire hazardous factors in building The deterministic methods of fire modelling may be classified as onе-zone, multy-zone and field (CFD) models depending on the extent of detalisation of description of thermogasdynamical parameters. One-zone models are the most simple among the fire simulation methods. Their main idea is an assessment of parameters of gaseous media through thermodynamic parameters, which are averaged across the whole volume of enclosure. A temperature of surrounding walls and other similar parameters are considered as surface averaged. But if gaseous media in enclosure is significantly non-uniform, the informativity of one-zone method can be insufficient for solving many fire safety problems. Such situation usually happens at the early stage of fire and at local fires, when jet flows caused by fire have obvious boundaries or media stratification takes place. Thus the scope of one-zone model application, when predicted fire parameters can be interpreted as real, is limited by volume fires, in which local values are close to those averaged by volume because of intensive mixing. More detailed description of fire can be obtained by means of multy-zone models. Multy-zone models are based on the suggestion on formation of two layers in the room: the upper layer of combustion products (smoke zone) and lower layer of unvitiated air (free zone). Besides these zones the fire plume is also usually considered and the other zones also can be added. Thus, the state of gaseous media in multy-zone models is assessed by the average parameters in each zone. The boundaries between zones are usually considered as moveable. But zone model requires large amount of simplifications based on prior suggestions about flow structure. Such method is not acceptable in the cases, when information about this structure is absent, and hence there is no basement for zone modelling. Besides that, for solving of fire safety problems more detailed information 16

17 is often required which can not be obtained on the basis of the parameters averaged by zone (layer). Field (CFD) models are more universal and powerful than zone models, because they are based on completely another principles. Instead of consideration of one or several zones one or several large zones field models use large amount (tens or hundreds thousands) of small control volumes, and no propositions are made on the structure of flow. For every control volume a set of partial differential equations is solved by numerical methods. These equations express the local conservation of mass, momentum and masses of species. Thus, the dynamic processes development is determined not by prior suggestions, but by results of the simulation only. Of course such models require significantly larger computational resources than one-zone and multi-zone models. Thus in each particular case it s necessary to use the model, which is both accurate and computationally acceptable for the problem under consideration. On the basis of the carried out researches and the analysis of the made assumptions, each type of models can be recommended to application in the following cases 1) One-zone method: Calculation of time of blocking of evacuation ways in the large building containing complex system of apartments with small volume and a simple geometrical configuration Calculation of time of blocking of ways of evacuation at realization of imitating modeling when calculation of stochastic character of a fire is more important, than exact and detailed forecasting of deterministic fire parameters; Forecasting of development of a fire in rooms where the characteristic size of the fire source is of the same order as the characteristic size of a room; 2) A zone method: Calculation of time of blocking of evacuation ways in systems of rooms of a simple geometrical configuration, with linear sizes close to each other. Advantage of a zone method before one-zone consists in an opportunity of its use for rooms of the 17

18 big volume (the size of the fire source is more less the sizes of a room), and also in an opportunity of calculation of times of blocking of working zones located on different levels within the limits of one apartment (inclined auditorium of a cinema, a mezzanine etc.); 3) A field method: Enclosures with a complex geometrical configuration, rooms with a plenty of internal barrier (atriums with system of galleries and adjoining corridors, the multipurpose centers with complex system of vertical and horizontal communications etc.); Apartments in which one of the geometrical sizes is significantly greater (less) than the others (the tunnels, the closed parking places of the big area etc.); Other cases when applicability or informativity of zone and one-zone models (unique constructions, fire spread along a facade of building, necessity of taking into account the systems of fire protection, which are capable to change qualitative a picture of a fire, etc.) The order of an estimation of individual fire risk At the first stage data gathering is made about object which includes inspection of: Space-planning decisions of object; thermophysic characteristics of structures, materials and equipment placed in object; Kind, quantities and arrangements of fuel; Amount and a probable arrangement of people in a building; The material and social importance of object; Systems of fire detection and extinguishing, smoke and flame protection, systems of people safety maintenance. On the base of the collected data, the analysis of fire danger of object is made. Thus it is taken into account: 18

19 Probability of occurrence of a fire; Possible dynamics of fire development; Presence and characteristics of systems of fire protection (SFP); Probability and possible consequences of influence of a fire on people, building constructions and material assets; Conformity of object and its SFP to the requirements of fire protection regulations. Then the expert choice of the fire scenario (scenarios) is made at which the worst consequences for people taking place in a building are expected. The formulation of the fire development scenario includes the following stages: - A choice of the location of fire origin and laws of its development; - Definition of calculation area (a choice of system of enclosures considered at calculation, definition of elements of internal structure of enclosures taken into account at calculation, condition of apertures e t.c.); - Definition of parameters of an environment and initial values of parameters inside the enclosure. The mathematical model of development of a fire is formulated. Modelling of the fire development dynamics is made. On the basis of results of calculations the value t бл is determined. The model of evacuation of people from a building is formulated. Construction of the evacuation scheme is carried out. Modelling of people evacuation is made. The calculated time of evacuation, t р, is determined. For buildings with stay of more than 50 persons the time of a congestion t ск is determined on each site of ways of evacuation. According to formulas (2) - (4) the calculation is made of individual risk Q в. Comparison of the value Q в with the value of acceptable individual risk Н Q В is made according to the formula (1). For buildings with stay of more than 50 person the conditions (5), (6) are also checked. 19

20 Analysis of fire safety of object Normative requirements for object are exist and executed нормативные требования no yes Choice of fire scenario. Formulation of mathematical models of fire development and people evacuation. Risk estimation Use of additional fire prevention measures Simulation of fire dynamics. Determination of evacuation ways blocking time Simulation of people movement. Determination of calculated evacuation time. Calculation of the value Q в no Is the risk value acceptable? yes All characteristic fire scenarios are considered? no да Conclusion about correspondence (noncorrespondence) of object to fire safety requirements 20 Fig. 4. The order of realization of an estimation of individual fire risk

21 The order of the account of additional fire-prevention measures at calculation of fire risk If the condition (1), and also conditions (5) and (6) (for buildings with mass stay of people) are not executed, it is necessary to provide one or several additional fire-prevention measures directed on maintenance of safe evacuation of people at a fire. The fire-prevention measures directed on maintenance of safe evacuation of people at a fire are: - application of additional space-planning decisions and the means providing restriction of fire spread; - provision of additional evacuation ways which are meeting the requirements of safe evacuation of people at a fire; - use of systems of the notification and management of evacuation of people at a fire of the raised type; - application of systems of collective protection (including smoke protection) from influence of hazardous factors of a fire; - restriction of amount of people in a building to the value, guaranteeing safety of their evacuation at a fire. Efficiency of each of the mentioned above fire-prevention measures is determined by a degree of their influence on parameters t р, t бл, t н.э., and for smoke protection system and for system of the notification and management of evacuation of people also by probability of performance of their task at a fire (R). Application as additional fire-prevention action of space-planning decisions and the means providing restriction of distribution of a fire is reached basically by maintenance of normalized limits of fire resistance and the lowered fire danger of facing building materials for walls of enclosures in which the probable fire origin is placed. Degree of influence of the given additional fire-prevention measure on dynamics of a fire and, accordingly, the value of parameter t бл it is determined by realization 21

22 of new calculation of t бл after making respective alterations into the space-planning characteristics of a building. If additional evacuation ways and exits are used as additional fire-prevention measure it is necessary to execute new calculation of evacuation time, t р, for the updated space-planning decisions. If the system of the notification and management of evacuation of people at a fire of the raised type is used as additional fire-prevention measure it is necessary to execute new calculation according of the parameter t р because of redistribution of evacuation streams and changes in the scheme of evacuation. Value of parameter R for the given technical decision is defined by technical reliability of used fire detection system, and by technical reliability of elements of the notification and management of evacuation of people system pointed out in the engineering specifications. At absence of data on parameters of technical reliability it is supposed to accept R СОУЭ = 0,5. Influence of smoke protection system on a level of maintenance of safe evacuation of people at a fire is estimated by means of calculation of value t бл with taking into account the characteristics of the used smoke protection equipment. Selection of parameters of the ventilating equipment is carried out by the authorized techniques. Thus it is necessary to apply zone or field models for such calculations. Value of parameter R for the given technical decision is defined by technical reliability of used fire detection system, technical reliability of elements of automatics of smoke protection control, and also by technical reliability of elements of smoke protection system pointed out in the engineering specifications. At absence of data on parameters of technical reliability it is supposed to accept R ПДЗ = 0,35. Restriction of amount of people in a building to the values guaranteeing safety of their evacuation from a building at a fire is taken into account by means of new calculation of the value of t р at existing space-planning decisions and new amount of people evacuated at a fire. 22

23 Conclusion The method of estimation of fire risk is presented with special emphasis on the methods of people evacuation modeling. References 1. Calculation of the required time of people evacuation from enclosures under fire: recommendations// VNIIPO MVD SSSR, p (in Russian) 2. Ryzhov A.M. Simulation of fires in enclosures with taking into account the combustion under natural convection conditions// Combustion, Explosion and Shock Waves, 1991, N3, pp Cox G., Kumar S. Field Modelling of Fire in Forced Ventilated Enclosures // Comb. Science and Tech V.52. P Lewis, M.J., Moss M.B. and Rubini, P.A. (1997) CFD modelling of combustion and heat transfer in compartment fires// Proc. of V Int. Symp. On Fire Safety Science, pp Application of field method of fire modelling in enclosures: recommendations// VNIIPO, 2003, 35p 6. SniP * Public buildings and constructions 7. SniP Public office buildings 8. GOST * Fire safety. General requirements. 9. Federal law of the Russian Federation from July, 22, 2008 N123-FZ Technical order about requirements of fire safety 10. Nikonov S.A. Development of the recommendations on the modelling of people flows movement in enclosures and organisation of notification under fire, PhD Thesis, 1986 (In Russian) 11. Kholshchevnikov V.V. Simulation of people flows. // in Modelling of fires and explosions ed. Brushlinski N.N., Korolchenko A.Ya.,2000, pp (In Russian) 12. Litskevich V.V., Prisadkov V.I., Fedorinov A.V. Numerical methods of the assessment of fire hazard and of the selection of the parameters of atria fire protection system//abstracts of XVI All-Russia Scientific and Practical Conference Large fires: prevention and extinguishing, part 2, Moscow, VNIIPO, 2001, pp (In Russian) 13. Ryzhov A.M. Differential modelling of fire dynamics and fire hazardous factor spread in enclosures// Fire and Explosion Safety, Moscow, 1994, N4, pp (In Russian) 14. Baranovski A.S.,Karpov A.V., Prisadkov V.I., Rodin V.S. Assessment of fire hazard of the corridor type hotels on the base of field model// Int. symp. Complex safety of Russia research, management, experience, 2004, pp (In Russian) 23