An Object-oriented Simulation (crisp 11) For Fire Risk Assessment

Abstract

Risk assessment methods are briefly reviewed and the advantages of simulation are discussed. FRS is developing a zone model (CRISP 11) of the complete fire system for this purpose. CRISP I1 is written in object-oriented fashion for maximum flexibility. The types of objects currently modelled are items of furniture, hot and cold gas layers, vents, walls, rooms, alarms, fire brigade and occupants of the building. The occupants exhibit the most complex object behaviour. Their actions in a domestic dwelling are governed by a table of rules. Each action requires the person to move to a specified room, followed by a time delay until the action is complete. The action may be abandoned before completion if room conditions become untenable, or the person is overcome by toxic products. In the final section of the paper it is shown how the model may be used for Monte-Carlo studies of risk in domestic houses. List of symbols area of burning item (&) discharge coefficient of vent length of simulation timestep (s) fractional effective dose of species X height of the flame (m) height of smoke:air interface in room i (m) latent heat of vapourisation/pyrolysis (kJ kg') rate of pyrolysis per unit area (kg m-2 s-1) number of samples used to estimate the mean probability that a fire is fatal pressure at height h (N m-2) fire's total heat output rate (kW) heat flux from sources other than flames (kW m2) radius of the fire (m) maximum fire radius(m) simulation time (s) random number with uniform distribution between 0 and 1 a multiplication factor in FED calculation vent width (m) yield of species X (kg of X per kg of fuel) height above virtual origin of plume (m)