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The program now implements the procedure in NBC Appendix D, 2.11.2, for fire design of glulam beams and columns.
Setting
A setting in the Design Settings allows you to specify whether the program designs glulam members for fire resistance, and if so, the default required fire endurance rating for new files. .
Input
The following inputs appear in the Beam Input view, Column Input view, and Concept mode Design Groups for beams and columns. They are enabled only if glulam is selected as a material and if beams or columns are selected as member type, and if the Design Setting for fire resistance rating is checked.
No of exposed sides
If zero, fire design is not performed, otherwise can be 3 or 4. Determines which equation is used in D-2.11.2 (1).
Duration
Required fire endurance, which can be 45 min, 1 hr, 1.5 hrs or 2 hrs. Note that NBC D-2.11.2 is used for glulam members required to have a higher maximum fire resistance rating than given in NBC 3.1.4.6 for heavy timber construction using 3.1.4.7, which is 45 minutes.
Protection
Materials covering the exposed member that protect it from burning and increase the fire endurance. ½” gypsum board increases endurance by 15 minutes, 5/8” gypsum board by 30 minutes, and two ply 5/8 by 1 hr.
Design
The equations in NBC Appendix D, 2.11.2 1) are used to determine fire endurance, to which is added the endurance due to fire protection, and this value is compared to the required resistance rating that you have input.
Equations
There are separate equations in D- 2.11.2 1) a)-d) for columns and beams and for 3- and 4- sided exposure. They depend on the load factor f and the lesser and greater section dimensions B and D.
Load Factor f
The load factor f is given in NBC as a graph relating the factored axial load vs. axial resistance for columns, and the factored bending moment vs. bending moment resistance for beams. For columns, separate graphs are used when the slenderness KL / B is greater or less than 12. These graphs correspond to equations found in APA Technical Report 10, which the program uses for its calculation. The curved portion of the graph for load / resistance ratios R greater than 0.5 is 0.7 + 0.3 / R for beams and non-slender columns and 0.9 + 0.3 / R for slender columns.
Protection
½” gypsum board, increases endurance by 15 minutes, 5/8” gypsum board by 30 minutes, and two ply 5/8 by 1 hr.
Output
The design check report shows the following output when fire design is activated for glulam beams and columns:
Force vs. Resistance Table
A line is added to the Force vs. Resistance table of the Design Check for the fire design criterion, showing the
Additional Data
In the CRITICAL LOAD COMBINATIONS section of the Additional Data of the Design Check, after the governing load combination for fire design, the program reports the factor f and the design ratio used for to determine it.
Design Summary
A column has been added to the Design Summary showing the fire design ratio for each passing section.
Concept Mode Results by Member
A column has been added to the Concept mode Results by Member showing the fire design ratio for each passing section.
Concept Mode Results by Group
If the design ratio for fire design is the highest for any of the design criteria, the program shows “Fire” as the governing criterion.