Performance-based Fire Safety Engineering Research Articles

Investigation of fires in a mechanically ventilated compartment using the CFD code FireFOAM

The outbreak of fires in nuclear power plants is a major risk due to the potential leak of radioactive materials. The use of traditional prescriptive fire safety regulations has shown its limitations and there is now a shift towards performance-based fire safety engineering, which requires well-validated fire models. Nuclear power plants require the use of mechanical ventilation, which provides dynamic confinement for nuclear materials by maintaining the required pressure. The occurrence of fires could potentially result in pressure variations within power plants. Although dynamic confinement along with other safety measures are in place to prevent fires, there is a continuous need to assess fire safety measures and reduce the risk of fire propagation with the use of fire simulation codes.The current study aims to build on existing research by making use of an emerging open-source computational fluid dynamics (CFD) fire simulation code known as FireFOAM, to predict fire behaviour in a mechanically ventilated nuclear compartment. An existing in-house modified version of FireFOAM developed by the authors’ research group, is further modified in the present work to include a Conjugate Heat Transfer (CHT) model to account for the heat transfer between combustion gases and solid boundaries. The CHT is validated using the experimental wall temperatures and heat fluxes. Furthermore, a mechanical ventilation model has been developed and implemented into FireFOAM. This newly modified version of FireFOAM is employed to predict the pressure variations in a nuclear compartment and the flow rates in the ventilation network. The predictions are compared to some experimental data from the open literature. Overall, it is shown that the mechanical ventilation model and the modified FireFOAM with CHT can predict the pressure variations and flow rates with a relatively good level of accuracy.

Building Information Modelling for performance-based Fire Safety Engineering analysis – A strategy for data sharing

The Hackitt Report into the tragic loss of 72 lives in the Grenfell Tower fire, identified failures and poor practices associated with the UK construction industry. To address these failures the report makes several recommendations, including the development of a “golden thread of information” to be embedded throughout the entire building lifecycle enabling the recording and preservation of information. This is to be achieved through Building Information Modelling (BIM). However, to create a “golden thread of information” in BIM from the Fire Safety Engineering (FSE) perspective particularly for the performance-based approach, many significant challenges and limitations must be resolved. These challenges include the fact that no FSE specific information exchange is available in BIM and that the results produced by fire and evacuation modelling tools are not explicitly captured in the BIM Industry Foundation Classes (IFC) Model. Of the FSE tools that support BIM, this is mainly limited to geometry extraction from an IFC file. In this paper, a practical conceptual strategy to pave the way to resolve these problems is proposed. A number of developments by the authors are discussed, forming part of an international collaboration project proposal administered by buildingSMART to enhance the IFC Model from the FSE perspective. Additionally, to evaluate and demonstrate the benefits of two-way data flow between BIM and FSE tools, a prototype system together with a preliminary FSE based analysis database have been developed. The work presented in this paper, provides a practical road map for creating a ‘golden thread of information’ in BIM for performance-based FSE analysis.

Inverse heat transfer modeling applied to the estimation of the apparent thermal conductivity of an intumescent fire retardant paint

Intumescent paints are widely used as passive fire protective materials in the building sector, primarily with regard to steel framed structures. The fire resistance of commercial intumescent coatings is typically tested experimentally using expensive and time consuming large-scale tests; conversely, the increasingly common performance-based fire safety engineering approach requires the development of techniques to generalize and predict the behavior of these protective materials. Recently, an experimental and data processing technique based on temperature measurements of the growing char layer and on the formulation of the inverse heat conduction problem within the system, has been proposed. This investigation indicated that an accurate and complete modeling approach is required to make robust predictions in the processing of the experimental data. In this paper, an enhanced procedure for estimating the apparent thermal conductivity of the intumescent paint is proposed and validated. The analysis presented in this study, performed with a physical and chemical characterization of the intumescent paint, allows estimation of the apparent thermal conductivity of the char layer with good approximation, thereby providing important information for assessing the fire protective capability of the coating under the fire safety engineering approach.

The impact of user decision-making in the application of computational compartment fire models

This paper describes a programme of blind modelling and benchmarking experiments that was part of a larger collaborative research project. The modelling and subsequent experiments were performed for a compartment representing a typical lounge in a residential occupancy with a number of different combustible items located in pre-defined positions, and a specific ignition source. The modellers were provided with information such as the compartment dimensions and number/size of ventilation openings, the location and nature of the combustible items, and the details of the ignition source. The objective for the blind modelling was to predict both the ignition times for each of the secondary items, as well as the heat release rate for the compartment. As input for the blind modelling, each modeller had to select a range of different input data that included a heat release rate curve and ignition properties for each combustible item. A series of three identical experiments were then carried out and the blind modelling predictions were compared to the experimental results. The specific focus of this paper is to describe what choices the different modellers made when selecting the different input data for the blind modelling exercise. The impact that this decision-making had on the predictions, and hence comparison with the subsequent experimental data, is discussed. The input data varied considerably between the different modellers, and this had a significant impact on the modelling predictions and the comparison with the experimental results. The user decision-making in this blind modelling and experimental benchmarking programme provides an illustration of one of the many aspects of the significant subjectivity that is likely to occur in everyday performance-based fire safety engineering (PBFSE). A comprehensive performance-based design will involve a number of performance objectives. The modelling and experimental programme presented in this paper deals with only one aspect of a life safety performance objective. Notwithstanding this limitation, any subjectivity of the type illustrated in this paper has the potential to create uncertainty as to the actual level of safety that will be achieved, a lack of confidence in the eyes of an official who may be reviewing/approving a design, and hence provide a barrier to the effective implementation of PBFSE.

A Framework for Selecting Design Fires in Performance Based Fire Safety Engineering

In fire safety engineering, the concepts of design fire scenarios and design fires are important for several reasons. In the design phases of a construction project the performance of safety measures, and the potential consequences of a fire, must be assessed by exploring design fire scenarios and design fires. Active and passive fire safety measures are dimensioned by exposing the systems to predetermined fire events. A predetermined fire event can also be used to extract fire-related quantities, such as smoke production rates, temperatures, and heat fluxes. Therefore fire events, which form the basis of these analyses, must be established. In this paper we report results from our investigation of current approaches used to determine design fires and their associated input variables. We present a framework to categorize design fires based on various engineering principles, in which fuel properties and environmental factors are emphasized. The framework provides a more consistent methodology than seen elsewhere, taking the perspective of the practicing engineer into account. Furthermore the creation of design fires encompasses considerations of uncertainty and validity.

Philip Humphrey Thomas (16 June 1926 – 14 January 2014)

Philip Humphrey Thomas (16 June 1926 – 14 January 2014)

Developing Probabilistic Design Fires for Performance-based Fire Safety Engineering

Research is ongoing in New Zealand to develop a new risk-informed fire safety design tool called B-RISK that is a combination of deterministic and probabilistic calculation functionality. The purpose of the tool is so that users can examine the risk and uncertainty that is part of modeling building fires in a rational and systematic fashion. A specific module in B-RISK that generates design fire inputs for iterative B-RISK simulations is described in the paper, and statistical distributions for the fire growth rate and peak heat release rate are developed for a residential-scale building occupancy. The use of this statistical data within B-RISK is also demonstrated and comparisons drawn with new building code compliance provisions that have recently come into effect in New Zealand.© 2013 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Asia-Oceania Association for Fire Science and Technology.

The concept of validation in performance-based fire safety engineering

The concept of validation is an important part of performance-based fire safety engineering. In this context the term validation is often used to describe the accuracy of a model or a calculation used to describe a phenomenon. It is also used to ensure credibility, being applied in statements such as: the model is validated for fires in the open, or, the model is validated for compartment fires.This paper examines the basic concept of validation. It addresses what it means to validate and what the concept of validation implies for performance-based fire safety engineering.The concept of validation has different meanings depending on the discipline and application in which it is used, for instance from an formal, empirical perspective validation may be used to determine the degree to which a model represents the real world, whereas in a functional perspective the concept of validation may be viewed as a way of obtaining credibility and trustworthiness for a model and also to determine the explanatory strength of a model.The field of fire engineering is based on natural science premises, especially in terms of the methods used to calculate the effects of a fire. However, a fire scenario is not only influenced by variables that can be assessed in a strictly physical sense: there are also other elements to consider, such as human and organizational behaviors. The concept of validation adopted in performance-based fire safety engineering should therefore also include wider considerations not directly measurable through experiment.

A study on the effect of project coordinators' knowledge on the use of performance-based fire safety engineering design in buildings

Alternative fire safety design is prima fasciae permitted in Hong Kong's legislative context. It is further explicitly allowed through the 1995/1996 fire safety-related building codes, that is, a performance-based track has been initiated for the past decade. Hong Kong certainly cannot be regarded as the first city/country to engage in such an effort. United Kingdom, for instance, has explicitly allowed the use of fire engineering in the 1985 Building Regulations. However, it has been noted that the building projects' coordinators, architects, building surveyors, engineers, etc, do not usually have much knowledge on the use of fire safety engineering (FSE) design. Such a situation may affect the extent of projects using performance-based approach. This paper presents a simplified system dynamics model to examine the effect of project coordinators' awareness on the use of FSE design in Hong Kong.

Fire Situation And Development Of Fire Safety Science And Technology In China

The fire direct property damage has gone up significantly with the development of industrialization and urbanization since the 1950’s in China. The number of casualties of fire has come down since the 1980’s while the mass casualties fire was significant. China governments at all levels, departments of fire protection, and the whole society have made great efforts to promote fire science research and its applications. The fire situation becomes relative stable in recent years. At present, the strength on fire research in China mainly includes the four fire research institutes of the Ministry of Public Security, the state key laboratory of fire science, fire enterprises and other fire research institutes. The researches have been carried out on fire detecting & alarming and fire suppression, fire resistance performance of constructions and fire prevention technology, fire modeling technology and performance-based fire safety design, fire protection on urban layout and fire fighting & rescue, technology of fire protection standardization, fire dynamics and fundamentals of fire protection since 1990. Emphasis has been put on the technology of fire prevention and fire-fighting rescue for high-rise building, underground building and large space building, and technology of prevention and control of urban fire and severe chemical disaster. In the future 5 years, the fire research work will be developed on theory of fire dynamic and fire risk, evaluation on urban area fire risk and capability of fire protection, techniques of new type fire facilities and engineering application, modernization of fire equipment, techniques of assessment and design on fire resistant of construction configuration, human behavior in fire, establishment and improvement of fire database, economics of fire protection and performance-based fire safety engineering.

An Investigation on the Building Officials' Perception for the Use of Performance-Based Fire Engineering Approach in Building Design

Traditionally, the spatial design of a building is influenced by the prescriptive fire safety codes. As buildings develop and become more complex and new materials are used, the prescriptive fire safety rules may not provide an efficient solution to the new building design. A system approach to the design of fire safety in buildings on the basis of performance criteria may be necessary. The recently published fire codes in Hong Kong have recognized the use of a performance-based fire safety engineering approach as a means to demonstrate the adequacy of fire safety design in a building. However, the judgement on the adequacy is made by the building control officials. Whether they believe the use of such a performance-based fire safety engineering approach can provide adequate fire safety level in a building can have influence on promoting performance-based design. This paper discusses the Hong Kong system and a survey on the views of the building control officials. The investigation indicates that the officials, in general, agree with the need of using performance-based approach, in particular to keep pace with the advancement of building technology. However, they have reservations on the adequacy of current tools for fire safety engineering design. Such views are in line with that of the building officials in the United States.

Fire Resistance of Loadbearing Steel-Stud Wall Protected with Gypsum Board: A Review

With the increased use of cold-formed lightweight steel framing (LSF), there is growing demand for the proper assessment of its performance in building fires. In partnership with the North American steel industry, the National Research Council of Canada (NRC) is conducting an experimental and analytical study on the fire resistance of loadbearing cold-formed steel-framed wall and floor assemblies. As part of this collaboration, this literature survey summarizes the information available on the topics related to the fire resistance of loadbearing cold-formed steel-stud walls clad with gypsum board. The current practice of establishing their fire-resistance rating, based on full-scale furnace tests, is assessed. Previous experimental and analytical studies on the subject and on the thermal and mechanical properties of the constituent materials—steel, gypsum board, and insulation—at elevated temperatures are also discussed. Future research needs are identified in the context of recent performance-based fire safety engineering concepts.

Evacuation behaviours of occupants with learning difficulties in residential homes

Purpose: This paper reports the results of unannounced evacuation of two residential care premises providing accommodation for people with learning disabilities. Method: Awareness of disability has in relation to fire safety focussed generally on mobility. With the advent of performance-based fire safety engineering codes which require the characterization of buildings and their occupants it is necessary to obtain knowledge of the likely behaviours of people with learning difficulties in an emergency. The unannounced evacuations which were conducted at 11.30 pm were video recorded to enable observation and an analysis of the residents' behaviours. Results and Conclusion: The results and observations obtained raise many issues; including transferable training skills, predictability of evacuation behaviours, and the need in performance code evaluation to consider the characterization of buildingsand their occupants as mutually inclusiveprocesses.

Performance-Based Fire Safety Engineering: an Introduction of Basic Concepts

The topics of performance-based fire safety engineering* and performance-based building codes are the focus of significant discussion, research, and development worldwide. Although the two topics a...