Timo Korhonen

FDS+Evac: An Agent Based Fire Evacuation Model

In this paper, an evacuation simulation method is presented, which is embedded in a CFD based fire modelling programme. The evacuation programme allows the modelling of high crowd density situations and the interaction between evacuation simulations and state-of-the-art fire simulations. The evacuation process is modelled as a quasi-2D system, where autonomous agents simulating the escaping humans are moving according to equations of motion and decision making processes. The space and time, where the agents are moving, is taken to be continuous, but the building geometry is discretized using fine meshes. The model follows each agent individually and each agent has its own personal properties, like mass, walking velocity, familiar doors, etc. The fire and evacuation calculations interact via the smoke and gas concentrations. A reaction function model is used to select the exit routes. The model is compared to other evacuation simulation models using some test simulations.

A Proposal for the Goals and New Techniques of Modelling Pedestrian Evacuation in Fires

In this article, we propose the goals for evacuation simulations in the context of the fire safety engineering. It is proposed that the safety of a building design should be measured using F-N plots that are based on the fire statistics. A new evacuation code is developed that allows the modelling of ‘panic’ situations and interaction between evacuation simulation and the state-of-the-art fire simulation. The major features of the new code are described and first preliminary results are shown. The method presented was found to run satisfactorily, and fast enough for practical purposes. When the results were compared against the results obtained using Simulex and buildingExodus codes, a good agreement was found in two of the three cases but for a case with congested corridor considerable differences occurred.

Modeling Evacuees’ Exit Selection with Best Response Dynamics

We present a model for occupants’ exit selection in emergency evacuations. The model is based on the game theoretic concept of best response dynamics, where each player updates his strategy periodically according to other players’ strategies. A fixed point of the system of all players’ best response functions defines a Nash equilibrium of the game. In the model the players are the occupants and the strategies are the possible target exits. We present a mathematical formulation for the model and analyze its properties with simple test simulations.

Two-model Monte Carlo Simulation of Fire Scenarios

A risk analysis tool called Probabilistic Fire Simulator (PFS) is developed for the computation of the distributions of fire model output variables and the sensitivities of the output variables to the inputs. PFS performs a Monte Carlo simulation using different fire models, including CFAST two-zone model and FDS fluid dynamics model. In this work, a new technique is developed for the use of two different fire models in the same Monte Carlo simulation. The two-model Monte Carlo technique provides a computationally effective means to improve the accuracy of the fast but inaccurate models, using the results of the more accurate but computationally more demanding models. The technique is tested in three scenarios: approximation of an analytical function, calculation of a ceiling jet temperature and a simulation of a simple room fire.

Application of RFID and Video Imaging on Evacuation Observations in Offices and Public Buildings

In this work, two different types of evacuation situations were studied in order to provide validation data for some aspects of the evacuation modeling. The first type was evacuation drills which are normally carried out as part of the safety training of the staff in public buildings and offices. The second type was actual evacuations which occur every now and then. The main techniques used for the observation of evacuation events were video cameras, Radio Frequency Identification (RFID), and surveillance cameras. A large amount of information was obtained and the problems in the application of the observation techniques were identified. In particular, the results show that when the RFID technique is used, the placement of the antennas and tags is very important. With careful placement of the antennas and tags, the reliability of the RFID technique as applied in the current work may be sufficient for scientific purposes. In the observation of an actual evacuation of a large shopping centre, the recordings of the surveillance cameras were used to measure the flow rates of people. The results are very promising and indicate that the collection of surveillance camera recordings from large evacuations should be started.

FDS+Evac Model Validation for Seated Row Arrangements: Aircraft and Cinema Theatre

Fire Dynamics Simulator (FDS) is open source computational fluid dynamics software for modeling practical fire problems. FDS includes a capability for the simulation of human egress process with and without the effects of fire, under the name of FDS+Evac. The human movement algorithm of FDS+Evac has been validated with experimental evacuation data and other evacuation models. But it is not yet validated on how to model evacuation process for seated row arrangements like aircraft, auditorium etc. Here an attempt has been made to model evacuation of humans in seated row arrangements with the help of two known experimental data, i.e., evacuation studies of a blended wing body aircraft (BWB) and a cinema theatre. The fire drill evacuation tests were modeled using FDS+Evac and validated with the experimental data and other human egress models. An appropriate set of FDS+Evac input parameters that seem to be well suited for the BWB case is presented in this paper. For the cinema theatre case the default parameter sets of FDS+Evac were seem to be appropriate.

Counterflow Model for FDS+Evac Simulations

We present a new method for modeling counterflow situations in crowds. Agents, describing individual pedestrians, are set to avoid the moving directions where there is counterflow and prefer the directions with forward flow. In dense counterflow situations, people tend to move shoulder first to occupy less space in the moving direction. If the elliptical cross-section of a human body is considered in a crowd model, the rotational positions in which the agents move affect the counterflow. In our model, agents try to rotate their bodies in certain counterflow situations to move shoulder first. The model is implemented in the FDS+Evac simulation software. Test simulations show that it is able to create rather realistic simulations of counterflow.

Quantitative application of Monte Carlo simulation in Fire-PSA

Abstract In a power plant a fire cell forms the basic subunit. Since the fire is initially located there, the full-scale time dependent fire simulation and estimation of target response must be performed within the fire cell. Conditional, time dependent damage probabilities in a fire cell can now be calculated for arbitrary targets (component or a subsystem) combining probabilistic (Monte Carlo) and deterministic simulation. For the latter a spectrum from simple correlations up to latest computational fluid dynamics models is available. Selection of the code is made according to the requirements from the target cell. Although calculations are numerically heavy, it is now economically possible and feasible to carry out quantitative fire-PSA for a complete plant iteratively with the main PSA. From real applications examples are shown on assessment of fire spread possibility in a relay room, and potential of fire spread on cables in a tunnel.

Bottlenecks in Evacuation Design Considering Both Structural and Human Behavioural Aspects: An Experimental Study

Evacuation experiments were performed in February and in March 2012 in Finland. The first set of experiments was done at Aalto University, where 83 university students were used as test persons in a setup where counter flows in corridor was examined. The second and third sets of experiments were conducted in Kuopio, where the persons attending the tests were students of Finnish emergency services college and conscripts, in total 60 persons. These later tests included a geometry related to stairs, where fatigue, fire fighters’ and normal people counter flows, and fire fighters’ rescue operations in stairs are examined. Trials were also performed using different door geometries. Two other scenarios were conducted in corridors, where density of smoke, different lightning conditions, and counter flows are examined on both group and individual levels. The preliminary results of the test series without throughout statistical analysis are presented in this paper.

Risk-based Attestation Of Fire Safety Of Wooden Fa~adesin Concrete-framed Residential Multistory Buildings

This study presents a fire risk analysis on the impact on fire safety of installation of a wooden facade to a suburb residential multistory building belonging to the fire class P1 defined in the National Building Code of Finland, which in practice means a concreteframed building. The risk analysis and the associated fire simulations are made using state-of-the-art techniques in the fire safety sciences and technology. The results of the study reveal that with respect to the overall fire safety of the concrete-framed residential multistory buildings, the role of the combustible wood as the facade material is insignificant: as is inevitable, the calculations bring out a small increment in the probabilities of fire spread from the room-of-fire-origin to the apartments above, but this increment is small as compared to the influence of several other factors which are not regulated by the Fire Regulations. In particular, the relatively small amount of wood on the facade that is likely to contribute to the external flaming would cause a much higher risk if it was installed as a lining inside the apartment-of-fire-origin. It is shown that the results obtained for the selected example building can be generalized to other buildings with reasonably similar characteristics.