The computer code OZone V2 has been developed to help engineers in designing structural elements submitted to compartment fires. The code is based on several recent developments, in compartment fire modelling on one hand and on the effect of localised fires on structures on the other hand. It includes a single compartment fire model that combines a two-zone model and a one-zone model.In this paper, the description of this compartment fire model is given. The main model is first presented. It consists of the usual zone model equations fully coupled with the partition model equations. The partitions are modelled by the finite element method. The switch from the two-zone to the one-zone model is then explained. The vertical, horizontal and forced vent sub-models are presented, followed by the fire source and the combustion models. A comparison between this code and another compartment fire model NAT is made. The OZone calculations are then compared to full scale fire tests.Considerations as to how this model is used for the design of steel elements will be presented in a companion paper (Fire Saf. J., this issue). specific heat of the material of the finite element j (J/kg K) c v (T) specific heat of the gas in the compartment at constant volume (J/kgK) C p (T) specific heat of the gas in the compartment at constant pressure (J/kgK) D fire diameter (m) E 1ZM (t s ) total energy in the two-zone model system (E g + energy in partitions) (J) E 2ZM (t s ) total energy in the two-zone model system (E U + E L + energy in partitions) (J) E g internal energy (1ZM) (J) E U and E L internal energies of, respectively, the upper and lower layer (2ZM) (J); g load vector (W/m 2 )Published in : Fire Safety Journal (2003), vol. 38, iss. 5, pp. 395- conductivity of the material of the finite element j (W/K s m 2 ) conductivity matrix of finite element j (W/K s m 2 ) conductivity matrix of partition (W/K s m 2 ) length of finite element j (m) rate of mass entrainment in the fire plume (kg/s) pyrolysis rate (kg/s) pyrolysis rate defined in the data (kg/s) total mass of fuel in the compartment (kg) mass of the gas in the compartment (1ZM) (kg) mass of oxygen in the compartment (kg) mass of oxygen in the compartment at initial time (kg) mass of oxygen coming into the compartment through vents (kg) mass of oxygen going out of the compartment through vents (kg) and mass of the gas of, respectively, the upper and lower layer (2ZM) (kg) rate of mass of gas exchange through vent, i = U or L or g. β = in or out. α = VV or HV or FV (kg/s). number of equations for the ceiling (dimensionless) number of equations for the floor (dimensionless) number of equations for the wall no. j (dimensionless) number of equations for all the partitions (dimensionless) absolute pressure in the compartment considered as a whole (Pa). convective part of the heat release rate (W) radiative part of the heat release rate (W) characteristic fire load density per unit floor area of compartment (J/m 2 ) design fire load density per unit floor area of compart...

To provide quantitative information on the ground acceleration necessary to break speleothems, laboratory measurements on samples of stalagmite have been performed to study their failure in bending. Due to their high natural frequencies, speleothems can be considered as rigid bodies to seismic strong ground motion. Using this simple hypothesis and the determined mechanical properties (a minimum value of 0.4 MPa for the tensile failure stress has been considered), modelling indicates that horizontal acceleration ranging from 0.3 m/s2 to 100 m/s2 (0.03 to 10g) are necessary to break 35 broken speleothems of the Hotton cave for which the geometrical parameters have been determined. Thus, at the present time, a strong discrepancy exists between the peak accelerations observed during earthquakes and most of the calculated values necessary to break speleothems. One of the future research efforts will be to understand the reasons of the defined behaviour. It appears fundamental to perform measurements on in situ speleothems.

The methodology implemented in the tool OZone V2 to design steel elements submitted to compartment fires is presented. Input needed to define a fire compartment are first quoted. The procedure to define the design fire is then explained. This procedure enables to take into account the benefits of active measures on the fire safety. The combined use of a two-and a one-zone model is then presented. A particular attention is given to the criteria of choice of the model and to the different scenarios that can occur. The calculation of steel element temperature is then explained. The proposed procedure takes into account the localised effect of a fire with the help of Hasemi's model. The fire resistance is then calculated with the EUROCODE 3 methods. An application is finally presented.