Design to Cope with Fully Developed Fires

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Publication, 685, pp. 198-276, 1979 Design to cope with fully developed fires Harmathy, T. Z. ABSTRACT: Since 80 to 90 percent of the combustible contents of building compartments are consumed during the period of fully developed f~e, the conditions that are expected to prevail during this period should be given special attention in the design of buildings for fire safety. The primary purpose of such design is to lessen the danger of spread of fire and smoke beyond the confines of the fire compartment. To provide a sound basis for the design, the characteristics of compartment fires, the factors that determine them, and the mechanisms by which fire and smoke spread through the building are discussed in detail. ASTM Special TechnicalThe most common method of protecting buildings against fire spread is compartmentation by fire-resistant boundary elements. The shortcomings of the conventional practice offire resistance allotment are analyzed and the principles of a recommended practice, referred to asfire tolerance design, are described.Information on the fire resistance of building elements is usually obtained by standard tests conducted on replicas of the elements. The meaning of the test results, however, is often unclear. It is becoming more and more acceptable to procure fire resistance information either by analytical and numerical studies, or by the use of extension and prediction formulas, graphs, and tables, many of which are reproduced for the designers' convenience.Owing to fundamental faults in the philosophy of fire resistance testing, information on fire resistance, either from tests or other means, cannot be directly utilized in the fire tolerance design. Methods of conversion between fire resistance and fire tolerance are presented, and techniques of designing for fire tolerance in stagnant and spreading fires, without resorting to fire resistance information, are outlined.Because of the prominent role that convection plays in the spread of fire and smoke, design for fire tolerance does not provide the complete answer to fire safety. The use of self-closing doors, cavity barriers and fire stops, and flame deflectors, that cut off the paths of convective fire spread, is an essential part of the overall fire defense scheme.An effective way of attacking the problem of spread of smoke is the pressurization of the principal shafts of the building. The danger of spread of both fire and smoke is greatly reduced by fire...

Assessment of Fire Engineering Design Correlations Used to Describe the Geometry and Thermal Characteristics of Externally Venting Flames

“…In the fully-developed fire stage the fire gas temperature reaches its maximum value and remains practically constant; in this case, the fire is usually ventilation-controlled, unless there are uncommonly large openings or a limited fuel surface area [23,24]. Due to differences in the severity of a fire event during the fuel-and ventilation-controlled stages, it is important to distinguish between the two cases [23][24][25]. There are several methodologies currently employed to characterise and distinguish between the two fire ventilation modes.…”

“…Conservative formulations based on simplified energy balance calculations and experiments on fire compartments (e.g. [7,8,21,25,26]), tend to accurately describe most ventilation-controlled fires; however their accuracy is limited in most fire events involving realistic fuel loads [23].…”

Analytical Behavior of Square Reinforced Concrete Stub Columns under Overall Fire and Axial Compression

“…The water vapor has influence on temperature movements of concrete at about 100 °C in the heating phase not in the cooling phase. The modified expression of concrete thermal properties proposed by Hamarthy [6] is used at elevated temperature.…”

An approach for developing probabilistic models for temperature‐dependent properties of construction materials from fire tests and small data

“…While fire resistance evaluation primarily favors deterministic approaches to assess fire response of structural systems, temperature‐dependent material models for properties of the different construction materials are not always available with high confidence. Codes, standards and reports, that is, ASCE manual on structural fire protection, 2 ACI guide, 3 Eurocode 2 4 and Eurocode 3, 5 Harmathy, 6 Bennetts, 7 Schneider, 8 and Anderberg, 9 documented, surveyed, and discussed the mechanical and thermal properties of the different building materials. Models for the thermal and mechanical properties of some building materials at elevated temperatures can be found in ASCE, 10 Eurocode 2, 4 and Eurocode 3 5 .…”