A probabilistic model of fire spread with time effects (original) (raw)
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DEVELOPMENT OF A MODEL FOR MITIGATING FIRE SPREAD IN MULTI-STOREY BUILDINGS
In the developing nations that are located in the tropical region; there is a growing trend of fire incidence in buildings without adequate development of fire prevention and/or reduction protocol. Thus, this study addresses the growth and spread of fire in multi-storey buildings. The rooms are structured as cells in order to reduce the flame spread from a single fuel item, by heat release, to other neighbouring items or rooms (otherwise known as cells). The philosophy is to reduce the advent of vertical and horizontal fire spread. Thus, the mathematical model for the spread of fire in buildings over a solid fuel surface is therefore developed using the adaptation, development and simulation of cellular automata (CA) discrete model. The von Neumann neighbourhood cell configuration is adopted. Hence, the surface of the fuel is analysed using a regular square array (i.e. cells), while the flame spread is depicted as a series of ignitions of surface elements. In which case, ignition of an element is evaluated by a combination of critical surface ignition temperature and cellular automata discrete techniques. The work displays the movement of fire, from its origin of ignition to other fuel igniting elements around it. Consequently, this spread to other parts of the building. However, the technique presented in this work attempts to reduce the rate of growth of the fire spread using the predictive fire growth probability approach. In other words, the application of the cellular automata, using a multi-storey building, is herein presented. The study has potential to advance knowledge of technical approach to stop fire spread in multi-storey building. Thus it improves fire risk management as well as reducing magnitude of fire disaster and losses in the multi-storey buildings.
Study on Fire Dynamic Development in a Multistory Building Compartment
Procedia Engineering, 2017
A simulation on fire dynamic development is needed to see how fire hazard of a building compartment, particularly in a multistory building. The fire development is affected by fire load content, passive (geometry and building openings) and active (detection, alarm and fire sprinkler) system arrangements. This paper discusses fire hazard of a compartment in a multistory building Rusunami in Indonesia. CFD-Fire Dynamic Simulator (FDS) is used for simulation. Fire load content is modelled by using mattress and wardrobe materials. Room layout is based on the built Rusunami. The results show that continuity of fire is affected by air flow through building openings. With less oxygen, at 390 seconds fire develops to produce maximum temperature of 150 o C, at 408 seconds fractional effective dose (FED) of toxic gases reach incapacitate of 0.5 and accumulation such gases significantly increased. At rich oxygen condition, the time needed from ignited stage until critical temperature is around 486 seconds, and after that in 48 seconds flash over occurred suddenly. This data will then be used as available safe egress time (ASET) to check the fulfillment of performance based fire protection approach in a building compartment.
Fire Safety Science, 2008
Fire safety regulations have a major impact on many aspects of the overall design of high-rise buildings, where complex and non-conventional architectural elements and designs can lead to fire environments diverging significantly from those used in the development of current codes and standards. Additionally, fire-fighting in high-rise buildings must be carried out from the inside of the building and fire-fighters must use stairwells or special fire-fighter lifts to access the floors which are on fire One way of assessing fire risk in such complex buildings is to use the principles of quantitative risk analysis (QRA), where deterministic and probabilistic models are combined to quantify risk and compare different fire safety strategies. In order to do this in high-rise buildings, account must be taken of the fire department intervention time in the QRA methodology, but data on the various parts of fire department action time has been scarce.. This paper focuses on the effect of the fire department intervention in high-rise building fires and how information on fire department intervention can be accounted for when using quantitative risk analysis to compare different fire safety strategies in such buildings.
FLAME: A Parametric Fire Risk Assessment Method Supporting Performance Based Approaches
Fire Technology
A fire risk assessment has always been a challenging task. Performancebased approaches to fire engineering have shown that risk-based decisions and fire scenarios are fundamental elements that must be considered in fire safety strategies. A correct assessment of the fire risk allows all the involved stakeholders to identify a specific strategy from among a variety of possibilities. A risk assessment is the best tool to identify comparable fire protection strategies and to measure the reduction in fire risk that can be obtained with each specific prevention and protection measure, i.e., by means of different fire safety strategies. The present paper illustrates a method that takes into account several well-known methods, even some that were developed as far back as in the early seventies. The method is named ''FLAME'' (Fire Risk Assessment Method for Enterprises). FLAME considers fundamental fire safety aspects instead of making use of sophisticated and time-consuming methods like CFD. FLAME uses the ''Fire Safety Concept Tree'', which is explained in detail in the NFPA 550 Standard, as a reference scheme. The method allows the risk to the occupants to be evaluated separately from the risk to the building. Over the years, we have tested the method considering different kinds of buildings and occupancies. We here report the results of an application of the FLAME method to hospitals and health-care facilities. Overall, about 300 compartments (overall size of about 60,000 m 2) were analysed, including two hospitals of about 200,000 m 2 each. The results of the risk estimation with the FLAME code have been found to be coherent with Italian fire code prescriptions. About 44% of the compartments were defined as being at a Medium risk and 39% as being at a high risk (according to the Italian Fire Code). More than 60% of the hospital compartments were defined as being at a High risk. A good agreement was obtained between the RSET results with those of the method proposed in FLAME when using the current performance-based regulation criteria. The RSET estimation in FLAME considers the occupants' behaviour and the actual characteristics of the occupants in clinics or hospitals, who often have difficulties due to reduced mobility or an incapacity to understand emergency instructions.
— This study aimed to develop an " improved simplified two-zone model authentication technology " in order to simulate the time to untenable conditions in compartments less than 200 m 2 in area, which include smoke layer temperature, visibility, carbon monoxide concentration, fractional lethal dose, and radiation heat flux. Based on reliability-based design and structure function, this study focuses on constructing " the stochastic model of egress safety/failure in a compartment fire ". Moreover, stochastic parameters and probability distributions were assumed. Random numbers of parameters were generated by Monte Carlo simulation. After several simulations, the failure probability of occupants egress due to one or more than one of the untenable conditions was obtained. After constructing the model, 200 m 2 occupants in a ALA PUB disco ballroom located in Taichung, Taiwan were taken as an example. The simulation of polyurethane furniture fire was executed 100 times. The results showed that installation of automatic fire alarm equipments and emergency broadcasting equipments can substantially reduce the untenable conditions and failure probability of occupants egress. Some ideas for fire officers and future studies for fire researchers were also recommended. HIGHLIGHTS The altitude effects on compartments less than 200 m 2 in area was explored and an " improved strengthened simplified two-zone model authentication technology " was developed. Time to untenable conditions was simulated and elucidated. Stochastic parameters and probability distributions was assumed. Random numbers of parameters were generated by Monte Carlo simulation. Based on reliability-based design and structure function, this study focused on constructing " the stochastic model of egress safety/failure in a compartment fire ". 200 occupants in a ALA PUB disco was taken as an example.
Fire load: Survey data, recent standards, and probabilistic models for office buildings
Engineering Structures, 2014
Fire load Fire load density Fire temperature Compartment fire Office Survey Probabilistic model Bayesian Performance-based design a b s t r a c t To enable a probabilistic performance-based approach to fire design, probabilistic models to represent the fire load are needed. Such probabilistic models are presented in this paper for office buildings. First, a literature review of recent fire load density surveys is presented. These surveys indicate a large range of fire load density values, and strong correlation between fire load density, compartment area, and use. However, current codes and standards (such as Eurocode and a recent publication of NFPA 557) that are used to estimate fire load density do not account for these variables and specify constant values. Based on survey data, a Bayesian probability approach is used to develop probabilistic models to predict the fire load density in office buildings (one for light-weight use and one for heavy-weight use). The models consider the size of the compartment and the office room use (general office, library, storage, etc.). The proposed models correlate well to the data and have a better fit than that obtained, using the Eurocode and NFPA 557. The proposed models for fire load density are then used to develop probabilistic models for the maximum fire temperature in a given compartment. Several scenarios with different floor areas and openings are defined and the fire load models developed in this paper are used to investigate the range of possible maximum fire temperatures and their corresponding probabilities. It is found that the proposed maximum temperature model results in a range of temperatures that correlates well with the test data and the Refined Tanaka Method proposed by a recent SFPE standard. It is shown that both the fire load density and the maximum temperature probabilistic models are well suited for application in a probabilistic performance-based approach to fire design.
RELIABILITY RISK ASSESSMENT IN HIGH RISE BUILDINGS IN CASE OF FIRE
The practice of structural fire safety engineering remains to be case-specific and the estimation of fire resistance of structures is mostly deterministic. Many researchers in structural fire engineering utilize the performance- based design method but these studies do not include the inherent uncertainties in both the demand and capacity. This paper investigates the structural fire reliability of tall buildings based on the framework used for earthquake hazard by the Pacific Earthquake Engineering Research (PEER) and Eurocode. The financial district of Istanbul in Turkey is taken as a case study for this research. Parameters such as building type and height, structural system, number of floors, floor area, number of elevators and stairs, the use of fire suppression systems, evacuation routes are provided by the municipalities in order to develop a probabilistic methodology to estimate the fire safety of these structures. The analysis is conducted by estimating the intensity or the hazard curve as described by PEER framework. The hazard domain includes random variables such as the fire load, the opening factor, the fire duration and the maximum fire temperature. The findings of this research will provide essential information on the fire safety risk of each tall building in a densely populated financial district. It will allow the municipalities and fire brigades to have a probabilistic risk assessment of these structures and develop evacuation and human rescue plans accordingly in case of a fire hazard. Further, this research will provide useful data to insurance companies to estimate fire hazard insurance premiums.
Probabilistic simulation of fire scenarios
Nuclear Engineering and Design, 2003
A risk analysis tool is developed for computation of the distributions of fire model output variables. The tool, called Probabilistic Fire Simulator (PFS), combines Monte Carlo simulation and CFAST, a two-zone fire model. In this work, the tool is used to estimate the failure probability of redundant cables in a cable tunnel fire, and the failure and smoke filling probabilities in an electronics room during an electronics cabinet fire. Sensitivity of the output variables to the input variables is calculated in terms of the rank order correlations. The use of the rank order correlations allows the user to identify both modelling parameters and actual facility properties that have the most influence on the results. Various steps of the simulation process, i.e. data collection, generation of the input distributions, modelling assumptions, definition of the output variables and the actual simulation, are described.
Applied Sciences
The current paper presents an application of an alternative probabilistic risk assessment methodology that incorporates technical, human, and organizational risks (T-H-O-Risk) using Bayesian network (BN) and system dynamics (SD) modelling. Seven case studies demonstrate the application of this holistic approach to the designs of high-rise residential buildings. An incremental risk approach allows for quantification of the impact of human and organizational errors (HOEs) on different fire safety systems. The active systems considered are sprinklers, building occupant warning systems, smoke detectors, and smoke control systems. The paper presents detailed results from T-H-O-Risk modelling for HOEs and risk variations over time utilizing the SD modelling to compare risk acceptance in the seven case studies located in Australia, New Zealand, Hong Kong, Singapore, and UK. Results indicate that HOEs impact risks in active systems up to ~33%. Large variations are observed in the reliabilit...