Performance-based Codes Research Articles

Fire Scenarios in the Enforcement of Performance-Based Fire Safety Regulations

The critical problem in any performance-based regulatory sys tem is "linking" the social objectives to the technical requirements. Since there is no technical method of deriving technical requirements directly from social objectives, society must express the social requirements in a technical form. Fire scenarios are one of the key methods for society to articulate technical require ments for fire safety in performance-based codes. Society must specify both de sign fires and the acceptable "conditions" for any analysis. Proponents of performance-based design must articulate methods for keeping all "estimates" within the approved range of values. Implementation of this social control sys tem can take place in a "regulatory design review" as part of the perfor mance-based code process. Examples are given of such reviews in the UK performance-based code environment.

Fire safety design based on risk assessment.

The present paper concerns a performance-based fire safety analysis and design of a high-rise building. The resulting fire safety recommendations are compared with those specified by acceptable solutions in terms of the earlier prescriptive building code. The respective risk to life resulting from the analysis is compared and discussed. The benefit and need of using a risk based verification method as a complement to a deterministic fire safety engineering method is demonstrated. The cost-effectiveness of different solutions is also demonstrated. This paper is based on the results from a case-study presented at the 2nd International Conference on Performance-Based Codes and Fire Safety Design Methods in Maui 1998.

Light-Weight Frame Wall Assemblies: Parameters for Consideration in Fire Resistance Performance-Based Design

With the advent of performance-based codes and fire safety design options, it is essential to determine parameters that affect the fire-resistance performance of assemblies. This paper presents the results of 17 full-scale fire-resistance tests conducted as part of a major industry-government research program investigating parameters that affect the fire-resistance performance of light-weight frame wall assemblies. These include the effects of insulation type, insulation width between studs, resilient channel location, gypsum board thickness, number of gypsum board layers, glass fiber in the gypsum board core, gypsum board mass per unit area, and stud type for light-weight frame wall assemblies finished with gypsum board. The effects of these parameters on the fire resistance are discussed.

Occupancy classification for performance-based life safety

A fundamental concept of fire safety codes is the categorization of buildings according to their occupancy or use. The intrinsic purpose of such classification is to simplify the application of code regulations. While actual occupancy fire risk varies in every building space, administration is greatly facilitated by classification into a small number of categories. In application, once determined, occupancy class becomes the basis for building fire risk assessments. Traditional occupancy classification by building function is challenged by modern multifunctional structures that do not fit the earlier categories. Furthermore, these traditional categories ape unnecessary given the current capabilities of performance-based fire safety design and by performance-based fire safety codes.

Analytical Methods to Evaluate Fire Resistance of Structural Members

Engineering standards will need to be developed to outline analysis methods to support performance-based codes being developed in the United States. This paper provides an overview of the state-of-the-art engineering methods for structural fire protection applications that could be incorporated into such an engineering standard. The overview addresses the technical basis, applicability, and utility of a representative sample of available calculation methods. These methods apply to a wide variety of structural members comprised of concrete, masonry, steel, and timber. An analytical assessment of fire resistance includes four principal aspects: fire exposure, material effects, thermal response, and structural response. A description of the fire exposure focuses on the heating conditions associated with the exposure. Material effects include material properties as a function of temperature along with physical or chemical effects of the elevated temperature exposure. Analyzing the thermal response results in determining the temperature profile within the exposed structural member. The ability of the structural member to support a load despite the effects of the fire exposure are incorporated in the analysis of structural response.

Performance criteria used in fire safety design

In many countries around the world, building codes are shifting from prescriptive- to performance-based for technical, economic, and social reasons. This move is made possible by progress in fire safety technologies, including the development of engineering tools that are required to implement performance codes. The development of performance-based codes follows a transparent, hierarchical structure in which there are usually three levels of objectives. The top level objectives usually state the functional requirements and the lowest level the performance criteria. Usually, one middle level exists, however, more levels can be used in this hierarchical structure depending on the complexity of the requirements. The success of performance-based codes depends on the ability to establish performance criteria that will be verifiable and enforceable. The performance criteria should be such that designers can easily demonstrate, using engineering tools, that their designs meet them and that the code authority can enforce them. This paper presents the performance criteria that are currently used by fire protection engineers in designing fire safety systems in buildings. These include deterministic and probabilistic design criteria as well as safety factors. The deterministic criteria relate mainly to life safety levels, fire growth and spread levels, fire exposure and structural performance. The probabilistic criteria focus on the incident severity and incident likelihood. Finally, the inclusion of safety factors permits a conservative design and allows for a smaller margin of error due to uncertainty in the models and the input data.

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.

Documentation for Performance-Based Fire Engineering Design in New Zealand

This paper summarizes the introduction of performance-based codes in New Zealand, and describes some difficulties and inconsistencies caused by poor documentation. Other issues related to the design and review process are also described. The paper describes the importance of good documentation for fire engineering design reports and for peer review reports. Performance-based fire engineering is a relatively new discipline, so fire engineering designs must be very well documented to ensure that the intended level of safety is achieved in a consistent way. Peer reviewing is an essential part of this process. Language: en

Fire safety codes for Hong Kong: Inadequacy for atrium design

The fire safety codes for buildings in Hong Kong are reviewed in terms of building type, building interior layout, construction materials, occupancy levels, circulation patterns, access and escape routes, fire detection and firefighting systems. The fire safety codes are valid only for traditional buildings in Hong Kong. Following these codes in modem buildings might lead to 'over-design' or to providing safety systems which are not workable in case of fire. The prescriptive approach is found to be insufficient to design fire safety for an atrium. It is timely to review the fire codes, to identify and revise those parts which are not workable. The possibility of implementing engineering performance-based fire codes is discussed. The fire safety requirements in atria are taken as an illustrative example. An engineering approach to designing fire safety is strongly advocated.

The Time Delay To Start Evacuation: Review Of Five Case Studies

Models to predict occupant response and evacuation will be an essential part of the move throughout the world toward performance-based codes and standards, as they are necessary for calculating the time required for occupants to reach safety, given a proposed design. To obtain realistic evacuation time predictions, it is essential to be able to accurately calculate the delay times occupants take before beginning evacuation. This paper reviews the findings from five evacuation studies. These studies include evacuation drills in midrise and highrise apartment'buildings and midrise office buildings. Findings from two fire incidents a six-fatality highrise apartment building fire in Canada and the World Trade Center bombing in New York City are also discussed. The findings of particular interest are those related to problems in alerting occupants, delays reported or observed during evacuations, and the reasons behind those delays.

Fire safety objectives for buildings

Rapidly expanding interest in performance-based codes has created increased attention to the objectives of fire safety. One of the more circumspect yet cogent discourses on this subject was presented by Professor David Rasbash, retired Head of the Department of Fire Safety Engineering at the University of Edinburgh. The following is excerpted from a lecture given to The Incorporated Association of Architects and Surveyors at Morecambe, October 1977, with permission of the author.—The Editor

NFPA's perspectives on performance-based codes and standards

Our ability to predict fire behavior and its effects on our lives has greatly improved over the past quarter century. Numerous scientific advancements have introduced new approaches and tools for the fire safety-related design of both the built environment and the development of new products. However, many of these new methods are not currently used on a routine basis.

A model for predicting the fire-resisting performance of small-scale cavity walls in realistic fires

A computer model that predicts the thermal response of a structural cavity wall to a wide range of time-temperature conditions is presented. With the advent of performance-based building codes, a need exists to prove the performance of wall assemblies in situations where it can be shown that the expected time-temperature conditions will be significantly different from the ISO 834 prescribed conditions.

A model for predicting heat transfer through noninsulated unloaded steel-stud gypsum board wall assemblies exposed to fire

With the advent of performance-based codes and performance-based fire safety design options, validated fire-resistance models have become essential. In this paper, a one-dimensional heat transfer model for steel-stud, noninsulated, unloaded gypsum board protected wall assemblies is presented. Also presented are a comparison between temperature predictions and measured temperatures at different locations in gypsum board wall assemblies as well as a comparison between the predicted and measured fire-resistance ratings. The model, which predicts slightly conservative fire-resistance ratings compared to the experimental measurements, is appropriate for most fire safety engineering applications. Considerations for further model development are identified.

Performance-based codes

Performance-based codes

International Implications of Performance Based Fire Engineering Design Codes

The trend towards performance-based design codes for fire safety design of buildings will provide greater busimess opportunities for international fire engineering firms. A common set of engineering tools and quantitative design methods based on a universal fire science will also encourage this process.Examples of performance-based approaches to fire engineering are presented as evidence of growing international cooperation. There are constraints, however, on transnational engineering opportunities. These are identified and include the lack of standards harmonization and differences in product approval and building permit processes between countries.

Changing the Regulatory System To Accept Fire Safety Engineering Methods

Globalization of trade and elimination of trade barriers indicate the need for performance-based regulations supported by fire safety engineering methods. These new fire safety engineering methods are presently being constrained by existing regulations, and thus the regulatory "system" needs to be changed. Changes will be needed by those who develop codes to deal with such issues as the levels of safety. The fire safety engineering qualifications for stakeholders and regulators will need to be upgraded, and they will have to be prepared to be licensed to practice. Other measures are outlined for all parties involved to ensure that fire safety engineering methods become the basis for performance-based codes.