Page 216 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

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BUILDING CODES, LOADS, AND FIRE PROTECTION*

4.44 CHAPTER FOUR

TABLE 4.19 Example of Restrained and Unrestrained Construction for Use in Fire Tests*
Type of construction Condition
I. Wall bearing:
a. Single-span and simply supported end spans of multiple bays.†
(1) Open-web steel joists or steel beams, supporting concrete slab, precast Unrestrained
units, or metal decking
(2) Concrete slabs, precast units, or metal decking Unrestrained
b. Interior spans of multiple bays:
(1) Open-web steel joists, steel beams or metal decking, supporting Restrained
continuous concrete slab
(2) Open-web steel joists or steel beams, supporting precise units or Unrestrained
metal decking
(3) Cast-in-place concrete slab systems Restrained
(4) Precast concrete where the potential thermal expansion is resisted Restrained
by adjacent construction ‡
II. Steel framing:
(1) Steel beams welded, riveted, or bolted to the framing members Restrained
(2) All types of cast-in-place floor and roof systems (such as beam-and- Restrained
slabs, flat slabs, pan joists, and waffle slabs) where the floor or roof
system is secured to the framing members
(3) All types of prefabricated floor or roof systems where the structural Restrained
members are secured to the framing members and the potential thermal
expansion of the floor or roof system is resisted by the framing system
or the adjoining floor or roof construction ‡
III. Concrete framing:
(1) Beams securely fastened to the framing members Restrained
(2) All types of cast-in-place floor or roof systems (such as beam-and-slabs, Restrained
flat slabs, pan joists, and waffle slabs) where the floor system is cast with
the framing members
(3) Interior and exterior spans of precast systems with cast-in-place joints Restrained
resulting in restraint equivalent to that which would exist in condition III
(4) All types of prefabricated floor or roof systems where the structural Restrained
members are secured to such systems and the potential thermal expansion
of the floor or roof systems is resisted by the framing system or the adjoining
floor or roof construction ‡
IV. Wood construction:
All types Unrestrained
*As recommended by ASTM E119, Appendix X3.
† Floor and roof systems can be considered restrained when they are tied into walls with or without tie beams, the walls being
designed and detailed to resist thermal thrust from the floor or roof system.
‡ For example, resistance to potential thermal expansion is considered to be achieved when:
(1) Continuous structural concrete topping is used.
(2) The space between the ends of precast units or between the ends of units and the vertical face of supports is filled with
concrete or mortar.
(3) The space between the ends of precast units and the vertical faces of supports, or between the ends of solid or hollow-
slab units does not exceed 0.25% of the length for normal-weight concrete members or 0.1% of the length for structural light-
weight concrete members.

4.12.8 Temperatures of Fire-Exposed Structural Steel Elements
Basic heat-transfer principles indicate that the rate of temperature change of a beam or column
varies inversely with mass and directly with the surface area through which heat is transferred to
the member. Thus the weight-to-heated perimeter ratio W/D of a structural steel member signifi-
cantly influences the temperature that the member will experience when exposed to fire. W is the

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