Calculation of fire safety risk in a building.
Calculation of fire safety risk in a building.
Calculation of fire safety risksrequires the definition of basic concepts. Fire risk is defined as a measure of the possibility of the realization of a fire hazard of a protected object and its consequences for people and material assets; such a phenomenon as acceptable fire risk implies a fire risk, the level of which is acceptable and justified based on socio-economic conditions; in addition, there is a concept of individual fire risk, which can lead to the death of a person as a result of exposure to hazardous fire factors. The calculation program is linked to such a document as a plan for evacuating people in case of fire.
Fire Risk Calculation. Program
Special documents related to the issue of fire safety, for example, «Conditions of compliance of the protected object», stipulate the calculation of fire risks. The program is implemented in accordance with the fire safety requirements established by federal laws on technical regulations.
Fire Risk Calculation (program) is based on the principle of comparing the standard value of fire risk and the estimated value of fire risk. For public, administrative and residential buildings, the calculation of fire safety risks is carried out in accordance with the «Technical Regulations on Fire Safety Requirements». The standard value of fire risk in buildings, structures and constructions should not exceed the value of one millionth per year when placing an individual at the point farthest from the exit from the building, structure and construction.
In addition, the calculation of fire risks (program) is given in the normative document «Methodology for determining the calculated values of fire risk in buildings, structures and constructions of various classes of functional fire hazard». Calculation of fire safety riskbegins with an analysis of the fire hazard of the building, then the frequency of occurrence of fire hazardous situations should be determined. The calculation also includes the construction of fields of hazardous fire factors, an assessment of the consequences of a fire that has occurred, and the calculation of the value of individual fire risk.
Examples of calculating fire risks
The principle of calculating fire risks sets a special procedure for calculating individual fire risk and social fire risk for personnel and visitors to public buildings. The numerical expression of individual fire risk and social fire risk is the probability of exposure to hazardous fire factors (OFP). Examples of calculating fire risksdetermine the probability of exposure to fire hazards for a fire hazard situation in which the location of the fire is on the first floor near one of the evacuation exits from the building. The estimated individual risk Qv in each building (room) is calculated using the formula: Qv = Qп Pпp (1 — Pe) (1 — Pп.з), where Qp is the probability of a fire in the building per year, determined by calculation or based on statistical data. Examples of fire risk calculationshow the principle of calculating the probability of evacuation Pe using the formula: Pe = 1 — (1 — Pe.p)(1 — Pd.v), where Pe.p is the probability of evacuation along evacuation routes; Pd.v is the probability of leaving the building through emergency exits or using other means of rescue.
Examples of calculating fire risksdetermine the time of evacuation of people tр from premises and buildings. It is established in the following ways: — by calculating the time of movement of one or several human flows through evacuation exits from the most remote places of placement of people; — using a mathematical model for determining the time of evacuation of people from a building taking into account the spread of combustion products and the characteristics of the categories of evacuees with random input parameters. The mathematical model for determining the time of evacuation of people from a building taking into account the spread of combustion products and the characteristics of the categories of evacuees with random input parameters is implemented in the Turbopascal environment. The choice of the method for determining the estimated evacuation time is made taking into account the specific features of the space-planning characteristics of the building, as well as the characteristics of the contingent of people in the building. If there is a fire alarm system in the building, ?н.э is taken equal to the response time of the system taking into account its inertia. In the absence of the necessary initial data for determining the start time of evacuation in buildings (structures) without warning systems, ?н.э should be taken as equal to 0.5 min for the floor of the fire and 2 min for the floors above.
In some cases, fire safety risk calculation requires planning one or more additional fire prevention measures aimed at ensuring the safe evacuation of people in the event of a fire: — the use of space-planning solutions and means to limit the spread of fire beyond the source; — the arrangement of evacuation routes that meet the requirements for the safe evacuation of people in the event of a fire; — the arrangement of automatic fire detection systems (automatic fire alarm systems), warning and control of the evacuation of people in the event of a fire; — the use of collective protection systems (including smoke protection) from the effects of hazardous fire factors; — the use of personal protective equipment for people from the effects of hazardous fire factors; — limiting the number of people in a building or structure to values that guarantee the safety of their evacuation from the building or structure in the event of a fire.