Noureddine Benichou

Literature Review of Performance-Based Fire Codes and Design Environment

Building codes in many countries around the world are shifting from prescriptive-based to performance-based, a move that is due, in part, to the negative aspects of the prescrip tive codes, to econ...

Performance criteria used in fire safety design

Abstract 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.

FIERAsystem: A Fire Risk Assessment Tool to Evaluate Fire Safety in Industrial Buildings and Large Spaces:

FIERAsystem is a computer model for evaluating fire protection systems in industrial buildings. The model has been developed as a tool to assist fire protection engineers, building officials, fire service personnel and researchers in performing fire safety engineering calculations, and can be used to conduct hazard and risk analyses, as well as to evaluate whether a selected design satisfies established fire safety objectives. While the model is primarily designed for use in warehouses and aircraft hangars, it can be modified for application to other industrial buildings. This paper describes the framework for FIERAsystem, along with its capabilities and flexibility. Individual models used to perform calculations are discussed, particularly those that calculate fire development and life hazard. A hazard analysis of an aircraft hangar is then described in detail, as an example of the types of calculations this model can perform. Methods used by the model to conduct risk assessments are also briefly described.

How Design Fires Can be Used in Fire Hazard Analysis

Many countries have introduced, or are planning to introduce in the near future, performance/objective-based codes. In a performance/objective-based code, the level of safety provided to the occupants in a building by a particular fire safety design will be assessed by the use of engineering analysis of fire development and occupant evacuation. Central to this performance-based approach is the use of suitable design fires that can characterize typical fire growth in a fire compartment. This paper gives a description of what features of design fires are needed and how they can help analyze fire hazards to the occupants in a building as a result of smoke movement, untenable condition in the stairs, and occupant response and evacuation.

Fire Resistance Performance of Lightweight Wood-Framed Assemblies

There are extensive efforts underway around the world, including those by the National Research Council of Canada (NRC), to develop fire resistance models. NRC is currently developing thermal and structural models for lightweight wood-framed assemblies, in collaboration with the Canadian wood industry. These models will be used in NRCs risk-cost assessment models as well as in the development of fire resistance design equations. To aid the development of fire resistance models, NRC has just completed, as a first step, a literature review on the efforts made to predict the fire resistance of lightweight wood-framed assemblies, with the objective of determining the gaps that need to be filled. This paper presents the results of this literature review, which include: standard versus real time-temperature fire curves, experimental studies, available fire resistance models and design methods and the identification of their limitations, charring of wood, and material properties of assembly components at elevated temperatures.

Investigation of the Performance of Emergency Ventilation Strategies in the Event of Fires in a Road Tunnel — A Case Study

A study has been conducted at the National Research Council of Canada to evaluate the effectiveness of in-place emergency ventilation strategies to control smoke spread in the event of a fire in the Louis-Hippolyte-La Fontaine road tunnel. Some of these strategies date back to the design of the tunnel in 1964. Following a recent fire, the operating instructions have been revised. A scientific-based numerical and experimental evaluation of these operating instructions is the main objective of this paper. The numerical evaluation uses the fire dynamics simulator (FDS) model to investigate smoke ventilation in tunnels. The experimental evaluation is used to provide the necessary initial and boundary conditions for the numerical solutions. A parametric study is performed, using the FDS model, assuming a heat source of 20 MW in the tunnel. Two fire scenarios, deemed to cover the two main situations likely to occur in the tunnel, are simulated. The parameters examined are the capacity of ventilation fans and th...

Performance in Fire of Fibre Reinforced Polymer Strengthened Concrete Beams and Columns: Recent Research and Implications for Design

This paper considers the fire performance of concrete beams and columns that have been strengthened with fibre reinforced polymers (FRPs). Results from four recent full-scale tests are presented. A newly developed type of insulation was employed and the thickness of the insulation (15 to 20 mm) was approximately half that provided in earlier tests. All of the members survived four hours of the fire exposure. A conceptual model for design to determine when insulation is required is also presented. Further research needed to fully develop the conceptual model to a more practical design tool is outlined.

Evacuation Movement in Photoluminescent Stairwells

An experiment was conducted in a 13-storey office building to assess the effectiveness of different installations of photoluminescent material (PLM) in stairwells. For the experiment four identical stairwells were used: three had different PLM installations and one had reduced lighting of an average of 37 lux. Video cameras and a questionnaire were used to gather data on the movement time and behavior of evacuees. Results from the study show that between 65 to 75% of the respondents felt comfortable going down the stairwells with PLM markings, with the visibility assessed as “good or excellent” in the two stairwells with PLM marking across each step. After the sound of the fire alarm, the average time taken by the first occupants to arrive at each stairwell was 1 min 7 s. Overall, the full evacuation lasted about 12 min. The results also indicate that during the busiest moment of the evacuation the mean speed of movement in the stairwells ranged between 0.40 and 0.66 m/s, while the density ranged between 1.56 and 1.60 p/m2. Occupants’ judgment of the installations showed the importance of marking across each step of the stairwell.