Zone Fire Model Research Articles

Structural safety assessment of concrete tunnel lining subjected to fire

The basis of a possible fire design and verification approach to the linings of RC tunnels, using the performance-based approach, is presented. Starting from an extensive literature review, a selection of the most relevant tunnel fires was analysed. The study of structural consequences of these real fires may be considered as experimental data of tunnel in fire, to define the possible fire damage levels. Back analyses were carried out to define the main parameters controlling each damage state, whose temperature range is determined via fluid-dynamic analyses based both on fire zone models and Computational Fluid Dynamic Modelling. Therefore, the novelty of this paper is that the proposed methodology introduces the structural damage levels for the tunnel lining in fire, according to a performance-based approach.In the second part of the paper, the proposed approach was applied to a real concrete tunnel to assess its potential fire damage level. First of all, the expected damage level of the underground structure was identified through the gas temperatures reached during different real fire scenarios, where no fire damage was observed. This result was confirmed by analysing both the temperatures and the stresses of the structural lining, through advanced thermo-mechanical analyses.

A discussion on design fires for high-speed railway train cars

High-speed rail systems are expanding everywhere for carrying thousands of passen-gers every day. Train cars in underground spaces travel under dense urban areas, tun-nels in mountainous places and bridges across rivers. Design fire in burning a train car should be studied carefully for fire hazard assessment in those long underground or en-closed spaces. There are full-scale burning testing results on the main combustibles in-cluding seat, curtain and passenger luggage in some train cars. The heat release rate of a high-speed train car model CRH1 will be studied using such data together with a two-layer fire zone model, the Consolidated Model of Fire and Smoke Transport (CFAST). Simulation will be performed on the full-sized train car with the heat release rate of the seat measured by experiment. Two fire scenarios with ignition points located in the front and rear areas of the train compartment are considered. The results of the fire simulations show that the heat release rate can reach 43 MW. The value is similar to the full-scale burning experiments on train cars in Sweden and South Korea. Active fire protection systems have to be seriously considered in those underground or enclosed areas.

Replicating the activation time of electronically controlled watermist system nozzles in B-RISK

This paper presents two series of enclosure fire experiments in which the activation time of electronically controlled watermist system nozzles and concealed sprinklers have been obtained. The first series experiments were aligned to the procedure given in the BS 8458 standard whereas the second series were configured to give slower growing fires than in the standard test.The activation of the two systems have been simulated in the B-RISK zone fire model. Activation characteristics for the concealed sprinklers have been taken from elsewhere in the literature. Representative activation characteristics for the electronically controlled watermist system nozzles have been determined. The selection of these characteristics has required a balance between the results from the two experimental series. By using an effective response time index of 20 m½s½ and an effective conductivity factor of 0.25 m½s−½ the predicted activation times are on average 14% slower across all of the enclosure fires.

Development and Validation of a Zone Fire Model Embedding Multi-Fuel Combustion

This paper presents the development and validation of a two-zone model to predict fire development in a compartment. The model includes the effects of the ceiling jet on the convective heat transfer to enclosure walls and, unlike existing models, a new concept of surrogate fuel molecule (SFM) to model multi-fuel combustion, and a momentum equation to accurately track the displacement of the smoke layer interface over time. The paper presents a series of full-scale fire experiments conducted in the IUSTI fire laboratory, involving different combinations of solid and liquid fuels, and varying the compartment confinement level. The model results are compared to the experimental data. It was found that for all fire scenarios, the experimental trends are well reproduced by the model. The SFM concept predicts oxygen and carbon dioxide concentrations in the extracted smoke to within a few percent of the measurements, which is a good agreement considering the sensitivity of the model to chemical formulas and combustion properties of fuels. Comparison with other measurements, namely average gas and wall temperatures, is also good. For the large fires reported in this study, the impact of the ceiling jet leads to a slight underestimation of wall temperatures, while the model gives conservative estimates for small fires.

Analysis of Zone Fire Models and their Application in Structural Fire Design

This paper is focused on a comparison of zone fire modelling software tools and their application in structural fire design. The analysis of the zone models is performed for five selected computer programs, namely Argos, Branzfire, B-RISK, CFAST, and OZone. The limits and input parameters ofthe zone fire modelling software tools are described. In each software, two variants of the analysed compartment are created for simulating two types of fire scenario, including the fuel-controlled fire and the ventilation-controlled fire. The burning regimes are defined based on two heat release rate(HRR) curves, determined according to EN 1991-1-2. The HRR curves parameters are used as the main input data into the fire modelling software. The fire simulation method in each fire modelling software is selected based on the software capabilities. Although each program requires a different amount of input parameters, the aim was to create the same model in all programs and to compare the results. The fire modelling software outputs are exported into a spreadsheet. Subsequently, a comparison of the resulting graphs is performed, particularly the heat release rate graphs and the upper layertemperature evolution graphs. The fire resistance assessment of a simply-supported concrete slab panel is performed for all zone fire models and then the results are compared. The fire modelling software tools are finally quantitatively and qualitatively evaluated and compared to assess their differences.

Изучение некоторых опасных факторов начальной стадии пожара в жилых помещениях с использованием современных технических средств

Introduction. An experimental installation with data logging based on the Arduino platform was developed to implement the approach used in modeling the spread of fire hazards in small rooms. The values of the heat flow from the convective column of the combustion center in the initial stage of the fire for a residential building with a predominant cellulose load were determined using obtained device according to the zone model of the fire. Goals and objectives. The purpose of this work is to create a compact device that allows us to quickly assess the development of fire hazards over time at the initial stage of their occurrence and to hold experiments at objects comparable in size to real fragments of buildings and premises. Methods. An experiment with the use of the field test method of fire hazard testing and an assumption about the possibility of using the developed device in testing the dynamics of the spread of fire hazards in rooms with a cellulose fire load was conducted. It is based on the data about the zonal modeling of the spread of fire hazards using modern technical means. Results and discussions. Experimental studies seem to be a necessary part of the forecast of the spread of fire hazards in residential premises. Field fire tests, which refer to tests of fragments of buildings and structures that are close in size to real objects, are able most accurately convey the conditions that occur in apartments and private homes during the fire phase. The current level of development of microelectronics makes it possible to use hardware and software for a wide range of people, including those who do not have a special education. Device, developed and created by the authors, is based on the Arduino Mega 2560 platform. It is compact and portable. It allows quickly receive and record data from the experiment of modeling fire conditions in small rooms. The obtained results allows us to estimate the level of heat flow of the convective column from the ignited wood, which simulates the fire load in the room to the ceiling, as well as the average temperature of the gas medium and the heat loss coefficient in the ceiling. Conclusions. The using of the experimental device presented by the authors makes it possible to optimize the obtaining of individual characteristics of the dynamics of fire hazards at the initial stage of ignition. Keywords: fire hazards, zone fire model, heat flow, field fire test, arduino platform

Generating Synthetic Sensor Data to Facilitate Machine Learning Paradigm for Prediction of Building Fire Hazard.

Using the zone fire model CFAST as the simulation engine, time series data for building sensors, such as heat detectors, smoke detectors, and other targets at any arbitrary locations in multi-room compartments with different geometric configurations, can be obtained. An automated process for creating inputs files and summarizing model results, CData, is being developed as a companion to CFAST. An example case is presented to demonstrate the use of CData where synthetic data is generated for a wide range of fire scenarios. Three machine learning algorithms: support vector machine (SVM), decision tree (DT), and random forest (RF), are used to develop classification models that can predict the location of a fire based on temperature data within a compartment. Results show that DT and RF have excellent performance on the prediction of fire location and achieve model accuracy in between 93 % and 96 %. For SVM, model performance is sensitive to the size of training data. Additional study shows that results obtained from DT and RT can be used to examine the importance of each input feature. This paper contributes a learning-by-synthesis approach to facilitate the utilization of a machine learning paradigm to enhance situational awareness for fire fighting in buildings.

Fire development in multi‐compartment facilities: PRISME 2 project

Fire development in multi‐compartment facilities: PRISME 2 project

Compartment fire predictions using transpose convolutional neural networks

This paper presents a data-driven approach to predict spatially resolved temperatures and velocities within a compartment based on zero-dimensional zone fire modeling using a transpose convolutional neural network (TCNN). A total of 1333 Fire Dynamics Simulator (FDS) simulations of simple two-compartment configurations with different fire locations, fire sizes, ventilation configurations, and compartment geometries were used in training and testing the model. In the two-compartment test cases 95% of TCNN predicted temperatures and velocities were within ±17.2% and ±0.30 m/s of FDS predictions. Although the model was trained and tested using a simple two-compartment configuration, the TCNN approach was validated with two more complex multi-compartment FDS simulations by processing each compartment individually. Overall, the flow fields in the multi-compartment validation tests agreed well with FDS predictions with 95% of TCNN predicted temperatures and velocities within ±11% and ±0.25 m/s of FDS predictions. Coupling a zone fire model with the TCNN approach presented in this work can provide spatially resolved temperature and velocity predictions without significantly increasing the computational requirements. Since the approach is based on a zone fire model, the TCNN approach presented in this work is limited to simplified geometries which can be sufficiently modeled using a zone fire model.

A-Evac: The Evacuation Simulator for Stochastic Environment

We introduce an open-source software for fire risk assessment named Aamks. This article focuses on a component of Aamks—an evacuation simulator named a-evac. A-evac models evacuation of humans in the fire environment produced by a zone fire model simulator. In the article, we discuss the probabilistic evacuation approach, automatic planning of exit routes, the interactions amongst the moving evacuees and the impact of smoke on humans. The results consist of risk values based on fractional effective dose and are presented in the form of various probability distributions and evacuation animations. The intended scope of Aamks is buildings, e.g., offices, malls, factories rather than stadiums or streets. We present the need for such software based on the current state of research and existing engineering tools in the probabilistic risk assessment domain. Then we describe a-evac and its details: geometry, path-finding, local movement, interaction with fire, and visualization. Given the above scope, the article contributes to the domain of probabilistic risk assessment by proposing: (a) stochastic approach to evacuation, (b) velocity-based model for evacuation, (c) evacuation software that interacts with fire conditions and zone fire models.

A Multi-observable Approach to Address the Ill-Posed Nature of Inverse Fire Modeling Problems

This study considers the development and evaluation of a prototype inverse fire model (IFM) aimed at predicting the heat release rate of a compartment fire using smoke layer information gained from building environmental sensors. The proposed methodology consists in: performing a search for the unknown heat release rate (HRR) by performing hundreds of different zone model simulations; comparing model predictions to observation data and thereby formulating an error function; using an optimization technique to minimize the error function and thereby producing a best estimate of HRR. The prototype IFM algorithm uses a zone fire model called BRI2002 (developed by the Building Research Institute in Japan) in conjunction with a genetic algorithm for optimization. The IFM algorithm is here applied to a reduced-scale laboratory experiment consisting of steady, over-ventilated, fire conditions in a simple multi-compartment (three rooms) configuration. The IFM algorithm is applied using a multiple-variable formulation in which both the fire size and the fire compartment venting conditions are assumed unknown, and using a one-observable or a two-observable scheme providing information on either the smoke layer temperature or on both the smoke layer temperature and depth. This framework is of particular interest because in the case of a one-observable scheme, the inverse fire problem is ill-posed, i.e. the optimization problem features multiple solutions and may converge to incorrect predictions of the fire size. This study shows that the two-observable scheme provides a way to regularize the inverse fire modeling problem, i.e. a way to provide a unique fire size solution. Our tests indicate that IFM-based estimates of HRR have an accuracy of better than 40%.

Evaluation of the Cables Types during the Fire Conditions in Nuclear Power Plants

The relatively high dangerous thermal effects of electric cable in the Nuclear Power Plants (NPPs) is the concern to study the cable insulation behavior during a fire accident. This paper provides a comprehensive evaluation for the thermal failure in different cables types of the standard main control room (MCR) in nuclear power plants. Evaluation of the effective parameters is carried out using (CFAST) zone fire modeling. The fire growth in a MCR, is modeled and simulated to determine the effect of thermal failure temperatures corresponding to cable functional failures. This is to develop realistic single point thermal failure thresholds and probability distributions for specific cable insulation types.The output data are assessed for the different cable insulation materials according to the specific thermal failure thresholds, as well as to develop the electrical cable thermal fragility distributions. The present results show the cable functionality interdependence on the external firing.

Storey stability of unbraced steel frames subjected to non-uniform elevated temperature distribution

Current studies on stability of steel frames are primarily based on the assumption that steel columns are subjected to uniform elevated temperature. However, the temperature distribution of real fire in a building may be non-uniform due to thermal buoyancy effect. In this study, the elastic stability of unbraced steel frames subjected to a non-uniform elevated temperature distribution along the longitudinal direction of the column is investigated based on the concept of storey based buckling and a two zone fire model. First, to simulate a steel column exposed to non-uniform elevated temperature, an analytical model is proposed to examine the effects of axial loading, non-uniform elevated temperature distribution, and thermal boundary restraints on the lateral stiffness of steel columns in unbraced frames. The lateral stiffness equation of the column model is derived based on Euler–Bernoulli beam theory. Then, the procedure to evaluate the stability capacity of unbraced steel frames subjected to non-uniform elevated temperature distribution is concluded. Numerical examples are presented to demonstrate the evaluation procedure of the proposed method and investigate the frame stability subjected to different scenarios of frame members exposed to the non-uniform elevated temperature distribution. The validity of the proposed method is verified by the numerical analysis with the use of finite element analysis.

Predicting Spill Plumes with the Fire Risk Zone Model B-RISK

Recent experimental research on spill plume entrainment has developed a range of empirically-based formulae for smoke management design. These formulae form the spill plume entrainment model in B-RISK, a new fire risk zone model. This article describes the performance of B-RISK in predicting spill plume entrainment. Selected experimental data from the series of reduced-scale experiments used to form the new design formulae have been used for model validation, along with other full-scale experimental data from ‘hot smoke tests’ conducted to assess the performance of installed smoke management systems. B-RISK provides predictions of the plume clear-layer height that generally agree with experimental results within the range of experimental error. This gives confidence in its use to predict spill plume entrainment for smoke management design purposes.

A model for the fire-fighting activity of local residents in urban fires

A physics-based urban fire spread model formerly developed by the authors was refined, with the additional consideration of the effect of the fire-fighting activity of local residents. The major refinements to the existing model are as follows: (1) the effect of water discharge against individual fire-involved compartments is evaluated by incorporating suppression factors into the governing equations of the one-layer zone fire behavior model, and (2) the behavior model of the local residents involved in fire-fighting activity is developed and combined with the existing urban fire spread model. The proposed model was applied to simulate fire spread behavior in a hypothetical urban area where 121 buildings of identical configuration were aligned in a regular pattern. The effects of parameters such as the fire detection time and the number of water supplies on the fire spread behavior were tested. In addition, the proposed model was applied to investigate the fire spread behavior of the 1976 Sakata Fire. The results showed that the fire-fighting activity was effective, especially for the suppression of fire spread in the direction orthogonal to the wind. Although there were discrepancies between the simulated burnt area and the actual burnt area identified by the post-event survey, a qualitative agreement on several features of the fire spread was obtained.

Characterizing Heat Release Rates Using an Inverse Fire Modeling Technique

A ubiquitous source of uncertainty in fire modeling is specifying the proper heat release rate (HRR) for the fuel packages of interest. An inverse HRR calculation method is presented to determine an inverse HRR solution that satisfies measured temperature data. The methodology uses a predictor-corrected method and the Consolidated Model of Fire and Smoke Transport (CFAST) zone model to calculate hot gas layer (HGL) temperatures in single compartment configurations. The inverse method runs at super-real-time speeds while calculating an inverse HRR solution that reasonably matches the original HRR curve. Examples of the inverse method are demonstrated by using a multiple step HRR case, complex HRR curves, experimental temperature data with a constant HRR, and a case with an experimentally measured HRR. In principle, the methodology can be applied using any reasonably accurate fire model to invert for the HRR.

Fire Engineering Approach of People Evacuation Assessment With a Practical Demonstration

This article presents some of the possible ways of an examination of people evacuation by fire engineering methods. Application of described methods is illustrated in a practical example of an office object. The expansion of fire in a part of characteristic floor of high-rise office is simulated by the selected zone (CFAST) and field (FDS) fire models. Some of the results obtained by the simulation, especially smoke layer decrease in the area and cumulative gas layer temperature, represent limit criteria for examination of safe evacuation from the assessed area. The article is an example of possible application of combination of manual computational processes and fire models.

Thermomechanical Analysis System for Building Structures under Fire Based on MSCPATRAN Platform

In order to analyze the behavior of building structures in a real fire, a numerical method is proposed, which employs fire zone model to simulate the fire growing and the temperature distributions in a firing room. Two computer programs are developed to predict the thermomechanical response of the structures, one for thermal response analysis, and another for structural analysis. The structural analysis program contains a fiber beam element and a layered shell element. These elements, validated against data from experimental tests, can be used to predict the response of beam/column and slabs in fire conditions. Based on these programs, a system for analyzing the behavior of structures under fire is developed on MSC/PATRAN platform. The behavior of building structures under fire can be simulated with this system and the results can be used as the reference for the fire safety analysis and assessment of general building structures under fire.

Ignition of Secondary Objects in a Design Fire Simulation Tool

A collaborative research project is currently in progress which aims to develop a fire zone model that deals with the uncertainty and variability associated with the modelling of design fires and design fire scenarios in buildings. As part of this research, a simple submodel has been developed which simulates the radiation received by secondary fuel items from both remote burning objects and enclosure surfaces and determines when secondary items ignite. An experimental programme was carried out to validate both the radiation and ignition predictions of the submodel, with good agreement being achieved between the theoretical model and actual intermediate-scale experiments in the laboratory. The experimental programme also serves to demonstrate the use of different radiation measuring devices.

Ignition of Secondary Objects in a Design Fire Simulation Tool

A collaborative research project is currently in progress which aims to develop a fire zone model that deals with the uncertainty and variability associated with the modelling of design fires and design fire scenarios in buildings. As part of this research, a simple submodel has been developed which simulates the radiation received by secondary fuel items from both remote burning objects and enclosure surfaces and determines when secondary items ignite. An experimental programme was carried out to validate both the radiation and ignition predictions of the submodel, with good agreement being achieved between the theoretical model and actual intermediate-scale experiments in the laboratory. The experimental programme also serves to demonstrate the use of different radiation measuring devices.