Copyright Materials. John Buddy Showalter, PE VP, Technology Transfer American Wood Council

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1 Program Registration Fire Design for Code Acceptance John Buddy Showalter, PE VP, Technology Transfer American Wood Council The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. Copyright 2011 American Wood Council. All rights reserved. Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. American Wood Council 2011 Learning Objectives At the end of this program, participants will be able to: 1. Apply provisions for designing wood members for fire safety including the Component Additive Method and flame spread ratings. 2. Design heavy timber for fire resistance. 3. Specify wood-frame fire-rated assemblies. 4. Specify wood products for use in the wild land urban interface.

2 Outline Design for Code Acceptance Fire Pubs Fire Rated Assemblies Component Additive Method Flame Spread Wildland Urban Interface Fire Rated Assemblies Fire Rated Assemblies DCA 3 Fire Rated Wood Wall and Floor/Ceiling Assemblies ASTM E 119 or UL 263 NFPA 251

3 Fire Rated Assemblies Fire Rated Assemblies 720 Prescriptive Assemblies Component Additive i Method (CAM) DCA 4 Component Additive Method (CAM) for Calculating and Demonstrating Assembly Fire Endurance CAM Membrane Table Time Assigned to Protective Membranes IBC Table (1) Description of Finish Time (minutes) 3/8" Douglas-fir plywood, phenolic bonded 5 1/2" Douglas-fir plywood, phenolic bonded 10 5/8" Douglas-fir plywood, phenolic bonded 15 3/8" gypsum board 10 1/2" gypsum board 15 5/8" gypsum board 20 1/2" Type X gypsum board 25 5/8" Type X gypsum board 40 Double 3/8" gypsum board 25 1/2" + 3/8" gypsum board 35 Double 1/2" gypsum board 40

4 CAM Wall Membranes Membranes on Exterior Face of Walls IBC Table (3) () Sheathing Paper Exterior Finish 5/8" T&G lumber 5/16" exterior grade plywood 1/2" gypsum board Sheathing paper Lumber siding: or Wood shakes & shingles 1/4" external grade plywood 1/4" hardboard Metal siding Stucco on metal lath Masonry veneer None None 3/8" external grade plywood CAM Wood Component Table Assigned Times for Wood Components IBC Table (2) () Description of Frames Time (minutes) Wood studs, 16 inches on center 20 Wood joists, 16 inches on center 10 CAM Cavity Insulation Table CAM Example 1 Assigned Times for Insulation of Cavity IBC Table (5) () Insulation Type Time (minutes) Interior Wall 2" X4" Wood Stud Mineral wool batts 15 5/8" Type X Gypsum Board 2" X 4" Wood Stud 20 minutes 5/8 " Type X Gypsum Board 40 minutes Total 60 minutes

5 CAM Example 2a CAM Example 2b Exterior Wall 2" X 4" Wood Stud Glass Fiber Insulation Exterior Wall 2" X 4" Wood Stud Glass Fiber Insulation 1/2" Gypsum Board 2" X 4" Wood Stud 20 minutes 1/2 " Gypsum Board 15 minutes Total 35 minutes 1/2" Gypsum Board & 1/2" Type X Gypsum Board 2" X 4" Wood Stud 20 minutes 1/2 " Gypsum Board 15 minutes Total 35 minutes 1/2" Type X Gypsum Board 25 minutes Total 60 minutes DCA 2 Design of Fire-Resistive Exposed Wood Members Beam Fire Test ASTM E 119 Limited to 1-Hour IBC Simplified approach Beams/Columns

6 Design Methodology for Beams and Columns D Heated zone Charred wood b = width (inches) of beam or larger column face d = depth (inches) of beam or narrower column face z = load factor r = load ratio t = fire endurance time (minutes) W Fire Endurance Time for Beams (1) fire exposure on four sides t=254zb[4-2(b/d)] 2.54 (2) fire exposure on three sides t = 2.54 z b [4-(b/d)] Fire Endurance Time for Columns (1) fire exposure on four sides t=254zb[3-2(d/b)] 2.54 (2) fire exposure on three sides t = 2.54 z b [3-(d/2b)]

7 Column Stability - Fixity Factors IBC Table (2) Buckling Modes Load Factor z For columns with K e l /d <11: z = 1.5 for r 50 z = /r for r > 50 Recommended K e Values Load Factor z For columns with K e l /d >11, and all llbeams: z = 1.3 for r 50 Load Ratio r r = Load max allowable load actual z = /r for r > 50 can be expressed as geometry or other ratio forms since load is a linear variable

8 Exposed dbeam Example Exposed dbeam Example Given: 8.75 x24 Glulam beam exposed to fire on 3 sides; S req d = 753 in 3 Need: 1 hour rating Calculate the Load Ratio, r r = S req d / S supplied = 753 in 3 / 840 in 3 = 90% Calculate the Load Factor, z z = /r = / 90 = Exposed dbeam Example Calculate the Fire Endurance Time, t t = 2.54 z b [4-b/d] = 2.54 (1.035)(8.75) [4-(8.75/24)] = 83 minutes Calculate up to 2-hours Bending / Compression / Tension Lumber / Glulam / SCL / Decking

9 Technical Report 10 Calculating the Fire Resistance of Exposed Wood Members Basis for NDS Chapter 16 provisions and simplified approach in Nonlinear char model eff = 1.2 n t where: eff = effective char rate (in/hr), adjusted for exposure time, t n = nominal linear char rate (in/hr), based on 1-hr exposure t = exposure time (hrs) Effective Char Rates and Char Layer Thickness (for n = 1.5 inches/hour) Required Fire Effective Char Effective Char Layer Endurance Rate, eff Thickness, char (hr) (in/hr) (in) 1-Hour ½-Hour Hour Load K * Allowable Design Capacity Member Capacity K Bending Strength 2.85 Tensile Strength 2.85 Compression Strength 2.58 Beam Buckling Strength 2.03 Column Buckling Strength 2.03 where: K = factor to adjust from allowable design capacity to j g p y average ultimate capacity

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11 Design Example Design Example Douglas fir glulam beams Span L = 18 feet Spaced at s = 6 feet Design Load q live = 100 psf q dead = 15 psf For the structural design of the beam, calculate the induced moment: Beam load: w total = s (q dead + q live ) = (6 )(15+100) Induced demand moment: M max = w total L 2 / 8 = (690)(18) 2 / 8 = 690 plf = 27,945 ft-lb Timber decking nailed to the compression edge of beams provides lateral bracing Size the beam for required bending strength for 1 hour fire duration Design Example Design Example Select a 6-3/4 x 12 24F-V4 Douglas-fir glulam beam Tabulated bending stress, F b, equal to 2400 psi Calculate the design resisting moment: M = F b S s = (2371)(162) / 12 = 32,009 ft-lb Calculate the beam section modulus: S = 2 = 2 /6 = 3 s BD /6 (6.75)(12) in Calculate the adjusted allowable bending stress: Assuming: C D = 1.0, C M = 1.0, C t = 1.0, C L = 1.0, C V = 0.99 F b = F b (C D )(C M )(C t )(lesser of C L or C V ) = 2400(1.0)(1.0)(1.0)(0.99) 0)(1 0)(1 0)(0 = 2371 psi Structural Capacity Check: M > M max 32,009 ft-lb > 27,945 ft-lb

12 Design Example Design Example For the fire design of the wood beam: the loading is unchanged, therefore, the maximum moment is unchanged, the fire resistance must be calculated Charring depth char for 1 hour duration: Required Fire Effective Char Effective Char Layer Endurance Rate, eff Thickness, char (hr) (in/hr) (in) 1-Hour ½-Hour Hour Substitute in residual cross-section dimensions for 3-sided beam into the section modulus relation, i.e.: 3-Sided Exposure (i.e. beams) b = B - 2 t d = D - t = B - 2 char = D - char Calculate charred beam section modulus exposed on 3-sides: S f = (B-2 char )(D- char ) 2 / 6 = (6.75-2(1.8))(12-1.8) 2 / 6 = 54.6 in 3 Design Example Calculate the adjusted allowable bending stress : F b = F b (lesser of C L or C V ) = 2400(0.99) = 2371 psi Calculate strength resisting moment using charred cross-section: M = K F b S f = (2.85)(2371)(54.6)/12 ) = 30,758 ft-lb Flame Spread DCA 1 Flame Spread Performance of Wood Products Fire Capacity Check: M > M max 30,758 ft-lb > 27,945 ft-lb

13 Flame Spread E 84 Tunnel Apparatus Flame Spread Class I or A 0-25 fire retardant treated wood Class II or B redwood cedar Class III or C most other wood species softwood plywood hardwood plywood particleboard based on Red Oak = 100 Smoke Developed Index available free from A smoke-developed index was also measured for some of the wood products listed in DCA 1. None of the products tested exceeded d 450, a limiting iti value commonly used in building code regulations.

14 Wildland Urban Interface Wildland Urban Interface 703A.7 - State Fire Marshal Test Standards Exterior Wall Siding & Sheathing 12-7A-1 150kW 10min Exterior Windows 12-7A-2 150kW 8min Under Eave 12-7A-3 300kW 10min Decking* 12-7A-4 80kW 3min Decking Alternate Method A 12-7A-4A 80kW 3min Ignition Resistant Materials 12-7A-5 ASTM E84/UL723 *Part B consists of 12mph wind for 40 min Wildland Urban Interface 704A - Ignition Resistant Construction SFM 12-7A-5 Extended 30 min. Flamespread Test ASTM E84 / UL 723 Used for FRTW FRTW Exterior Use XYZ Company FRTW Shakes and Shingles Class B Wildland Urban Interface 707A Exterior Covering 2x nominal rafter tails and dblocking exempt Exterior Walls - 707A.3 Ignition resistant Heavy timber 4x or greater Log walls Tested per SFM 12-7A-1 5/8 Type X Gypsum between framing and siding 1-hour fire resistive s assembly

15 Wildland Urban Interface 707A Exterior Covering Open Eaves - 707A.4 Ignition resistant 5/8 Type X Gypsum between covering and roof deck 1-hour fire resistive assembly 2x nominal rafter tails and blocking exempt Gable-end end overhangs exempt Fascia/Trim exempt Wildland Urban Interface 707A Exterior Covering Enclosed Eaves - 707A.5 Ignition resistant 5/8 Type X Gypsum between framing and covering 1-hour fire resistive assembly Tested per SFM 12-7A-3 Gable-end end overhangs exempt Fascia/Trim exempt Wildland Urban Interface Wildland Urban Interface 707A Exterior Covering Porch Ceilings/Floors/Appendages /A - 707A.6-9 Ignition resistant 5/8 Type X Gypsum between framing and covering 1-hour fire resistive assembly Tested per SFM 12-7A-3 Architectural trim exempt Heavy timber exempt 709A Decking <10 of the building <10 of the building SFM 12-7A-4 + SFM 12-7A-5 SFM 12-7A-4A + Ignition Resistant Siding Exterior FRTW ASTM E84 Class B

16 Wildland Urban Interface Wildland Urban Interface WUI Product Handbook fire pdf/bml/wuiproducts.pdf Lists SFM approved products Siding Windows/Doors Eaves Decking Ignition-Resistant materials Wood Roof Shakes/Shingles Siding and Sheathing Manufacturer-specific Generic Siding over 7/16 Plywood/OSB No holes or loose knots ASTM E 84 Class B or C Species-dependent Use DCA 1 Flamespread Wildland Urban Interface AWC Helpdesk Decking Manufacturer-specific Generic Over 2x6 Doug Fir or better joists 24 o.c.orless or ASTM E 84 Class B or C Species-dependent Use DCA 1 Flamespread info@awc.org (202)

17 Course Evaluations Questions? In order to maintain high-quality learning experiences, please access the evaluation for this course by logging into CES Discovery and clicking on the Course Evaluation link on the left side of the page. This concludes The American Institute of Architects Continuing Education Systems Course The Wood Products Council