Page 219 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch04.qxd 9/29/05 5:09 PM Page 4.47

BUILDING CODES, LOADS, AND FIRE PROTECTION*

BUILDING CODES, LOADS, AND FIRE PROTECTION 4.47

• In effect, the standard fire test presumes that structural members will be fully loaded at the time of
a fire. It is unlikely that maximum structural loads will occur simultaneously with an uncontrolled
severe fire.
• Given the scale of available laboratory facilities, the structural interaction of the entire framing sys-
tem cannot be directly evaluated. In effect, ASTM E119 unrestrained ratings presume virtually no
structural interaction, i.e., simple supports without continuity. To some degree, structural interac-
tion is indirectly considered in establishing restrained ratings. The boundary conditions are arbi-
trary, however, and the extension to real buildings is largely based on judgment.
As a consequence of these shortcomings, a more rational engineering design for structural fire
protection is desirable. This advanced work can be performed by qualified structural/fire consultants
in accordance with performance-based design concepts and standards, using state-of-the-art fire and
structural modeling tools. Standards of a more rational type have been developed and are now used
routinely in Japan, Australia, and throughout much of Europe (European Convention for
Constructional Steelwork, Model Code on Fire Engineering, 2001), and are being developed in the
United States by the American Society of Civil Engineers in cooperation with the Society of Fire
Protection Engineers. Also, criteria for rational structural design for fire conditions are now provided
by the AISC in Appendix 4 of the “Specification for Structural Steel Buildings,” 2005. Topics
addressed include engineering analysis, determination of heat input, thermal expansion, and degra-
dation of mechanical properties at elevated temperatures.
(The SFPE Handbook of Fire Protection Engineering, National Fire Protection Association,
Quincy, Mass.)

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