Commentary — Appendix 4 Structural design for fire conditions

Appendix 4 includes the following major changes and additions in this edition of the Specification:

(1) The temperature-dependent stress-strain equations from the Eurocode have been incor- porated.
(2) Appendix 4 now includes prescriptive steel fire-protection design equations based on standard ASTM E119 fire tests.
(3) New provisions are included for calculating fire-resistance ratings of composite plate shear walls and composite floor slabs on steel deck.
(4) Simple methods of analysis now include concrete-filled composite columns and concrete-filled composite plate shear walls.
(5) Provisions have been added to permit incorporation of increased rotational restraints from cooler columns above and below an exposed column.
(6) A new critical temperature method to calculate member temperature as a function of the applied load has been added for tensile yielding, flexural buckling, and flexural yielding.

Portions of Appendix 4 have been taken from the following sources:

• 2018 International Building Code (ICC, 2018)
• ASCE/SEI/SFPE 29-05, Standard Calculation Methods for Structural Fire Protection (ASCE, 2005)
• 2005 Eurocode 3: Design of Steel Structures; Part 1.2: General Rules, Structural Fire Design (CEN, 2005b)
• 2005 Eurocode 4: Design of Composite Steel and Concrete Structures; Part 1.2: General Rules, Structural Fire Design (CEN, 2005d)

Table C-A-4.1 provides a roadmap of the specific portions of Appendix 4 that are attributed to these four sources.

C-4Commentary — Appendix 4 Structural design for fire conditions