BCD201: Fire Design Methodologies for Code Acceptance

AMERICAN FOREST & PAPER ASSOCIATION American Wood Council Engineered and Traditional Wood Products American Wood Council Engineered and Traditional Wood Products BCD201: Fire Design Methodologies for Code Acceptance A F & P A Copyright 2004 American Forest & Paper Association, Inc. All rights reserved. Welcome to ecourse BCD 201 titled Fire Design Methodologies for Code Acceptance. Copyright 2004, 2007 American Forest & Paper Association, Inc. All rights reserved. 1

Copyright of Materials This presentation is protected by US and International copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the American Forest & Paper Association / American Wood Council is prohibited. Copyright 2004 American Forest & Paper Association, Inc. All rights reserved. 3

BCD201: Learning Outcomes By the end of this ecourse, you will be: 1. Able to apply provisions for designing wood members for fire safety, including the Component Additive Method 2. Able to design heavy timber for fire resistance 3. Able to determine flame spread ratings 4. Familiar with fire-rated assemblies In this ecourse, you will learn to apply provisions for designing wood members for fire safety, including: using the component additive method, designing heavy timber for fire resistance, flame spread ratings, and fire-rated assemblies. 4

Design for Code Acceptance Pubs AWC publishes 4 Design for Code Acceptance (DCA) publications and one Technical Report that deal with fire. 5

Outline DCA1: Fire Spread Performance of Wood Products DCA3: Fire Rated Wood Wall Assemblies DCA4: Component Additive Method (CAM) for Calculating and Demonstrating Assembly Fire Endurance DCA2: Design of Fire-Resistive Exposed Wood Members TR10: Calculating the Fire Resistance of Exposed Wood Members Detailing for Fire Control This presentation will highlight all 5 documents and show by example how to use the information contained in them. Also, information on detailing for the prevention of fire spread will be covered. 6

Design for Code Acceptance 1 DCA 1 Fire Spread Performance of Wood Products Design for Code Acceptance 1 (DCA 1): Flame Spread Performance of Wood Products. 7

Design for Code Acceptance 1 E 84 Tunnel Apparatus The Steiner Tunnel Test is used to determine flame spread rating. It is calibrated with Red Oak flooring and measures the relative spread of fire over time. The measure is expressed as an index where the Red Oak standard is given the value of 100, and cementitious board is given a value of zero. 8

DCA 1: Flame Spread Ratings for Various Wood Products Class I or A 0-25 fire retardant treated wood Class II or B 26-75 redwood cedar Class III or C 76-200 most other wood species softwood plywood hardwood plywood particleboard based on Red Oak = 100 Typical flame spread ratings for various woods are grouped for acceptance in the building code provisions. The lower the rating number, the lower the ability of flame to spread. Some examples of flame spread rating numbers are: FRTW: 0-25 Redwood & Cedar: 26-75 Other woods: 76-200 DCA 1 now lists flame spread ratings for a variety of domestic wood species and materials and is updated frequently on the web as new material ratings become available. 9

Design for Code Acceptance 3 DCA 3 Fire Rated Wood Wall Assemblies revised with new title and contents 2001 DCA 3: One-hour Fire Rated Exterior Walls. 10

DCA 3: Designing for Fire Endurance Tools for designing wood frame construction to provide fire endurance: traditional ASTM E-119 Assemblies Component Additive Method (DCA 4) Beam/Column Calculation Method (TR10) There are several code accepted methods for designing to provide fire endurance. ASTM E119 assemblies; component additive method (CAM); beam/column calculation method. The latter two methods will be discussed later in order of complexity. DCA 3 lists and describes complete assemblies that have been approved to meet a specific time rating for fire endurance. This is the simplest approach to designing to meet a given fire endurance requirement in the building code - simply pick an approved assembly that meets the time required, i.e. a one-hour fire assembly. Each assembly has been furnace-tested to the standard ASTM E119. 11

ASTM E-119 Joist Assembly Typical 1 hour rated assembly: 19/32" plywood 15/32" plywood 2" x 10" joists @ 16" o/c 1/2" type X gypsum wallboard The figure above shows a 1-hr E119 joist assembly (UL512). It uses ½" type X gypsum board on 2x10 floor joists with 2 layers of plywood: 19/32" flooring over 15/32" subfloor. 12

ASTM E-119 Truss Assembly Typical 1 hour rated assembly: 3/4" plywood parallel chord truss steel furring channel 5/8" proprietary type X wallboard The above figure is a typical 1-hr E119 truss assembly (UL528). It uses 5/8" type C gypsum board on furring channels (note the channels are doubled at board edges). This is on parallel chord trusses with 1 layer of 3/4" plywood. Note that each assembly is generic in description, and that each assembly description is cataloged by Underwriters Laboratories in terms of a catalog number. 13

ASTM E-119 Truss Assembly As constructed: The figure above shows what that assembly looks like as constructed prior to testing in an E- 119 furnace. 14

DCA 3: Designing for Fire Endurance DCA 3 lists and describes many of the common fire rated wood assemblies for wood construction by duration list and descriptions are updated frequently as test results become available The figure above shows the form of a DCA 3 rated assembly description sheet. 15

Design for Code Acceptance 4 DCA 4 Component Additive Method (CAM) for Calculating and Demonstrating Assembly Fire Endurance DCA 4: Component Additive Method (CAM) for Calculating and Demonstrating Assembly Fire Endurance. Should a tested assembly, not be available, or applicable, one can create a conforming assembly using the Component Additive Method. This is most frequently utilitarian when designing in existing structures where the existing assemblies may not be easily altered. 16

DCA 4: CAM Background Component Additive Method (CAM) developed by NRC using NBS tests recognized by SBCCI and ICBO published by BOCA for new and existing assemblies CAM was developed by the National Research Center of Canada using National Building Science data, based upon Harmathy's 10 rules of fire endurance. Recognized by ICBO and SBCCI and published by BOCA, the CAM applies to both new and existing assemblies. The complete background to CAM is described in DCA 4, along with the required tables and examples for design. CAM is implemented by adding time contributions from each materials layer through the thickness of the entire assembly. 17

DCA 4: CAM Membrane Table Time Assigned to Protective Membranes 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 Here is an example of the table from DCA 4 of times assigned to protective membrane materials, i.e. ½" gypsum board: 15 minutes; 5/8" doug-fir plywood: 15 min. 18

DCA 4: Wall Membranes Membranes on Exterior Face of Walls 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 The table lists the minimum membrane protection required when the assembly is asymmetrical. Membrane protection on each side is required if exposure to fire may occur from either side. 19

DCA 4: CAM Wood Component Table Assigned Times for Wood Components Description of Frames Time (minutes) Wood studs, 16 inches on center 20 Wood joists, 16 inches on center 10 Wood roof and floor truss assemblies 24 inches on center 5 Here is another table from DCA 4 listing assigned times for various wood components, for example: studs 16 o.c. - 20 min. joists 16 o.c. - 10 min. trusses 24 o.c. - 5 min. 20

DCA 4: CAM Cavity Insulation Table Assigned Times for Insulation of Cavity Insulation Type Time (minutes) Mineral wool batts 15 Glass fiber batts, non-loadbearing walls 5 Here is another example of a table from DCA 4 listing assigned times for cavity insulation, i.e. mineral wool batts assigned a time of 15 minutes. 21

DCA 4: CAM Example 1 Component Additive Method (CAM) - Interior Wall 2" X 4" Wood Stud 5/8" Type X Gypsum Board 2" X 4" Wood Stud 20 minutes 5/8 " Type X Gypsum Board 40 minutes Total 60 minutes To apply Component Additive Method, take each material layer in the assembly, find its respective assigned time from the DCA table, and sum the materials times together. The summed time yields the time rating for the assembly. Example: 2x4 studs@16"o.c. = 20 min.; 2 layers 5/8" type X gypsum board = 40 min.; total = 60 min. This interior wall assembly would satisfy a 1 hour requirement. 22

DCA 4: CAM Example 2a Component Additive Method (CAM) - 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 Consider this exterior wall for a 1 hour time requirement. From the DCA 4 tables, the materials times are as follows: 2x4 studs@16"o.c. = 20 min.; 1 layer ½" gypsum board = 15 min.; total = 35 min. That s less than the 1 hour required. 23

DCA 4: CAM Example 2b Component Additive Method (CAM) - Exterior Wall 2" X 4" Wood Stud Glass Fiber Insulation 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 To meet the minimum 1 hour requirement, add an additional layer of ½" type X gypsum = 25 min., for a total of 60 min. Now the assembly is OK. 24

Design for Code Acceptance 2 DCA 2 Design of Fire-Resistive Exposed Wood Members Design for Code Acceptance 2 (DCA 2): Design of Fire Resistive Exposed Wood Members. Should you have exposed structural wood material, you can provide meaningful fire protection by design. DCA 2 provides the necessary guidance and formulae based on extensive fire testing and char rate modeling. 25

DCA 2: E-119 Fire Test Beam Fire Test The figure above shows a glulam beam being tested in an ASTM E119 furnace. 26

DCA 2: Charred Cross-section Beam Fire Design Heated zone D Charred wood W Analysis of wood members subjected to fire yields the following characteristics about their cross section. Wood is a natural insulator that chars from the outside-in at a measurable, predictable rate when exposed to fire. The outer layer is a char layer (sacrificial wood). The heated zone is where some strength reduction in the wood occurs due to elevated temperature. The inner zone is unaffected during the fire. This affords good residual loadcarrying ability for the wood member based on the size or cross section of the inner zone. 27

DCA 2: Section Terminology Design Methodology for Beams and Columns b d z r t is the width (inches) of beam or larger column face is the depth (inches) of beam or narrower column face is the load factor is the load ratio is the fire endurance time (minutes) The following terminology is used in this calculation method (see slide). 28

DCA 2: Beams Fire Endurance Time for Beams (1) fire exposure on four sides t = 2.54 z b [4-2(b/d)] (2) fire exposure on three sides t = 2.54 z b [4-(b/d)] The beam fire endurance calculation formulae is: (see slide). Note the distinction for 3-sided vs. 4-sided exposure. 29

DCA 2: Columns Fire Endurance Time for Columns (1) fire exposure on four sides t = 2.54 z b [3-2(d/b)] (2) fire exposure on three sides t = 2.54 z b [3-(d/2b)] The fire endurance time equation for columns is: (see slide). Again, note the distinction between 3-sided and 4-sided fire exposure. 30

DCA 2: Columns Column Stability - Fixity Factors Buckling Modes Recommended K e Values 0.5 0.7 1.0 1.0 2.0 2.0 K e is normally assigned to be 1.0 for pin/pin end fixity conditions. The table, shown above, recommends K e values based upon the buckling modes expected in the condition of the design. 31

DCA 2: Load Factor Load Factor z For columns with K e /d <11: z = 1.5 for r 50 z = 0.9 + 30/r for r > 50 Load factors are shown graphically in DCA 2. Load factor, z, for columns with slenderness ratio K e l/d < 11 (see slide). 32

DCA 2: Load Factor Load Factor z For columns with K e /d >11, and all beams: z = 1.3 for r 50 z = 0.7 + 30/r for r > 50 Again note, load factors are shown graphically in DCA 2. Note the distinction for slender columns with Ke l/d > 11 and for all beams (see slide). 33

DCA 2: Load Ratio Load Ratio r r = Load max allowable load actual can be expressed as geometry or other ratio forms since load is a linear variable r is the Load Ratio and can be expressed in geometry or in other ratio forms since load is a linear variable (see slide). 34

DCA 2: Exposed Beam Example Given: 8.75 x24 Glulam beam exposed to fire on 3 sides; S req d = 753 in 3 Need: 1 hour rating Consider this example: Design an 8.75 x 24 glulam beam for 1-hr fire endurance rating assuming 3 sides exposed to fire. Assume a required section modulus (S req'd ) of 753 in 3 based on actual loads. 35

DCA 2: Exposed Beam Example Calculate the Load Ratio, r r = S req d / S supplied = 753 in 3 / 840 in 3 = 90% Calculate the Load Factor, z z = 0.7 + 30/r = 0.7 + 30 / 90 = 1.035 The Load Ratio is the applied load on a member as a percentage of the allowable load. The Load Factor, z, is determined from this load ratio (see slide). 36

DCA 2: Exposed Beam 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 the fire endurance time in minutes using the time formula for a 3-sided exposed beam (see slide). This is equal to 83 minutes. This beam exceeds the one-hour (60 minutes) requirement in this design. If the time, t, calculated is less than 60 minutes, then to get the one-hour requirement for this exposed beam, the section size would need to be increased slightly. 37

Technical Report 10 TR10 Calculating the Fire Resistance of Exposed Wood Members Technical Report 10 (TR 10): Design of Fire Resistive Exposed Wood Members, forms the technical basis for DCA 2. It is also complete with detailed explanation, test results, and comprehensive calculation examples. 38

Technical Report 10 Superior fire performance of heavy timbers attributed to the charring effect of wood Benefits of charring an insulating char layer is formed protects the core of the section The physical basis for the DCA 2 and TR 10 documents is the charring characteristic of wood when subjected to fire. Charring of wood occurs at a measurable, predictable rate, and because of wood s insulation properties, the cross-section interior remains capable of sustaining and carrying the load. 39

Technical Report 10 Experimental charring rates measured in various parts of the world appear to be consistent North America - Standard fire endurance test ASTM E-119 many other countries - comparable fire exposure in ISO 834 Effects of fire on adhesives synthetic glues used in the manufacture of glulam do not adversely affect performance Charring rates of wood under standard fire exposure conditions were measured in studies world-wide. Glued products did not perform any differently than their solid counterparts. 40

Analog for Cross-Sectional Dimensions A standard terminology was established for describing the charred and uncharred section dimensions for two common fire exposures. 41

Estimating Cross-sectional Dimensions due to Charring 4-Sided Exposure (i.e. columns) b = B - 2βt d = D - 2βt 3-Sided Exposure (i.e. beams) b = B - 2βt d = D - βt 2-Sided Exposure (i.e. decking) b = B - βt d = D - βt where: β t is the char rate of the material is the fire exposure time which resulted in these relations for charred width and depth as shown in the table above. 42

ASCE 29 Method for Beams (Lie Empirical Method) t f = 2.54 Z B (4-2B/D) 4-sided exposure 2.54 Z B (4 - B/D) 3-sided exposure where: Z = 1.3 R < 0.5 0.7 + 0.3 / R R > 0.5 and, where: R is the ratio of applied to allowable load (load ratio) t f is the fire endurance time (minutes) Here is the ASCE 29 Method for beams of 3- and 4-sided exposure. Note that the the failure time is expressed in minutes (see slide). 43

ASCE 29 Method for Columns (Lie Empirical Method) t f = 2.54 Z D (3 - D / B) 4-sided exposure 2.54 Z B (3 - D / (2B)) 3-sided exposure For short columns (K e / D < 11): Z = 1.5 R < 0.5 0.9 + 0.3 / R R > 0.5 For long columns (K e / D > 11): Z = 1.3 R < 0.5 And, where: 0.7 + 0.3 / R R > 0.5 R is the ratio of applied to allowable load (load ratio) t f is the failure time (minutes) Likewise, here is the ASCE 29 Method for columns of 3- and 4-sided exposure, and varying slenderness to allow for the buckling effect as charred section increases with exposure time. Note that the the failure time is expressed in minutes (see slide). 44

New Mechanics-Based Design Method expands the use of large exposed wood members: loading conditions fire exposures mechanical properties stress interactions expanded range of wood products This design method is a rational approach that allows for exposed structural wood members to be used in structures that could be exposed to fire. 45

Design Considerations predicts reduced cross-sectional dimensions adjusts for charring at the corners accounts for the loss of strength and stiffness in the heated zone The equations used in this method account for all the charring characteristics of a wood cross-section exposed to fire. 46

Model for Charring of Wood Nonlinear char model used - nominal linear char rate input. To account for rounding at corners and reduction of strength and stiffness of the heated zone, the nominal char rate values, β n, are increased 20%. β eff = 1.2 β n t 0.187 where: β eff is the effective char rate (in/hr), adjusted for exposure time, t β n is the nominal linear char rate (in/hr), based on 1-hr exposure t is the exposure time (hrs) In terms of the charring characteristics of wood, this is the char model used. 47

Effective Char Rates and Char Layer Thickness (for β n = 1.5 inches/hour) Required Fire Effective Char Effective Char Layer Endurance Rate, β eff Thickness, α char (hr) (in/hr) (in) 1-Hour 1.80 1.8 1½-Hour 1.67 2.5 2-Hour 1.58 3.2 and these are the charring results based on a typical char rate of 1.5 inches per hour. 48

Design for Member Capacity Dead Load + Live Load K * Allowable Design Capacity Where: K is a factor to adjust from allowable design capacity to average ultimate capacity The factor, K, adjusts from allowable design capacity of the member to average ultimate capacity - the maximum capacity the member can physically sustain (no safety factors). 49

Allowable Design Stress to Average Ultimate Strength Adjustment Factor Member Capacity Bending Moment Capacity, in-lb. 2.85 Tensile Capacity, lb. 2.85 Compression Capacity, lb. 2.58 Beam Buckling Capacity, lb. 2.03 Column Buckling Capacity, lb. 2.03 K This table lists the values of K for various mode capacities to adjust to an ultimate strength basis. 50

General Comparison Given the theoretical derivation of the new mechanics-based design method, existing test results from fire tests of exposed, large wood members were compared against the model predictions. International and North American test data were reviewed. The theoretical model was checked against full scale tests from all over the world. 51

Predicted Time vs. Fire Test Observed Time (Wood Beams Exposed on 3-Sides) Mechanics-Based Model Prediction Predicted Time to Failure (minutes) 160 140 120 100 80 60 40 20 0 0 20 40 60 80 100 120 140 160 Observed Time to Failure (minutes) Model and test agreement were good for wood beams exposed on 3 sides. 52

Predicted Time vs. Fire Test Observed Time (Wood Columns Exposed on 4-Sides) Predicted Time to Failure (minutes) 140 120 100 80 60 40 20 0 Mechanics-Based Model Prediction 0 20 40 60 80 100 120 140 Observed Time to Failure (minutes).also for wood columns exposed on 4 sides. 53

Predicted Time vs. Fire Test Observed Time (Wood Tension Members Exposed on 4-Sides) Predicted Time to Failure (minutes) Mechanics-Based Model Prediction 160 140 120 100 80 60 40 20 0 0 20 40 60 80 100 120 140 160 Observed Time to Failure (minutes) and for wood in tension exposed on 4 sides. 54

Predicted Time vs. Fire Test Observed Time (Decking Exposed on Bottom Side) Mechanics-Based Model Prediction Predicted Time to Failure (minutes) 100 80 60 40 20 0 0 20 40 60 80 100 Observed Time to Failure (minutes) as well as for decking exposed on the bottom side. 55

Technical Report 10 Expands the uses for large, exposed wood members (tension, bending/compression, bending/tension members, decking) Expands applicability of current methods to other EWP s (SCL) Expands use of large, exposed wood members to 2 hour fire endurance applications. The model and methodology described in TR 10 holds several advantages for structural wood applications. 56

TR 10: 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 Timber decking nailed to the compression edge of beams provides lateral bracing Size the beam for required bending strength for 1 hour fire duration Here is a detailed example, worked from start to finish - with more depth than that presented previously in DCA 2. Consider Douglas fir beams spanning 18 feet and spaced 6 feet apart. The beams support 100 psf live load and 15 psf dead load. Timber decking laterally braces the compression flange of the beams. Size the beam for a 1 hour rating. 57

TR 10: Design Example For the structural design of the beam, calculate the induced moment: Beam load: w total = s (q dead + q live ) = (6 )(15+100) = 690 plf Induced demand moment: M max = w total L 2 / 8 = (690)(18) 2 / 8 = 27,945 ft-lb Solution: First, calculate the induced demand moment based on the tributary width of 6 feet (beam spacing). 58

TR 10: 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 beam section modulus: S s = BD 2 /6 = (6.75)(12) 2 / 6 = 162.0 in 3 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) = 2371 psi Pick a beam, calculate its section modulus from actual dimensions, and the adjusted allowable bearing stress of the material. 59

TR 10: Design Example Calculate the design resisting moment: M = F b S s = (2371)(162) / 12 = 32,009 ft-lb Structural Capacity Check: M > M max 32,009 ft-lb > 27,945 ft-lb Multiply the adjusted allowable bending stress by the section modulus to get the maximum resisting moment offered by your chosen beam. Check for adequacy, and in this case, OK. 60

TR 10: 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 From TR 10 table, find charring depth α char for 1 hour duration: Required Fire Effective Char Effective Char Layer Endurance Rate, β eff Thickness, α char (hr) (in/hr) (in) 1-Hour 1.80 1.8 1½-Hour 1.67 2.5 2-Hour 1.58 3.2 Now, design the cross-section for fire endurance. A certain amount of the cross-section will char during the duration of the rating time, reducing the cross-section size required to sustain load. From the table in TR 10, find the char depth for the duration you are seeking, in this case, 1 hour. 61

TR 10: Design Example 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 - 2βt d = D - βt = B - 2α char = D - α char Calculate charred beam section modulus exposed on 3-sides: S f = (B-2α char )(D- α char ) 2 / 6 = (6.75-2(1.8))(12-1.8) 2 / 6 = 54.6 in 3 Determine the charred section dimensions and calculate a new charred section modulus for the residual section. 62

TR 10: Design Example Calculate the adjusted allowable bending stress (some adjustment factors don t apply and may have been other than 1.0 before): 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 Fire Capacity Check: M > M max 30,758 ft-lb > 27,945 ft-lb Recalculate the adjusted allowable bending stress, since not all of the adjustment factors apply here and may have been other than 1.0 before. Determine the strength resisting moment based on the charred cross-section, and in this case is good for a 1 hour fire duration. 63

TR 10 Conclusions Full-scale test results indicate that the mechanics-based method will conservatively estimate the fire endurance time of large, exposed wood members. Given the theoretical derivation of the new mechanics-based design method, it can be easily incorporated in current wood structural design provisions. Incorporation of new mechanics-based method in the NDS will assist in the proper design of large, exposed wood members for standard fire exposures. TR 10 concludes that the modeled behavior is conservatively accurate, that it can be easily implemented as a design process, and that will permit designers to use exposed large section wood members in structural applications that could be subject to fire exposure. 64

Standardization of New Method New Design Method has been approved for inclusion in: 2001 National Design Specification for Wood Construction. This design approach has been approved for inclusion in the 2001 NDS. 65

Detailing for Fire Control To reduce the spread of fire, use: fire blocking prevents movement of flame and gases to other areas of the building through small concealed spaces in framing and building components draft stopping prevents movement of air, smoke, flame, and gases to other areas of the building through large concealed spaces such as attics and floor assemblies with suspended ceilings or open-web trusses Apart from designing cross-sections to withstand fire endurance, there are other design provisions that can be implemented to reduce the spread of fire in wood frame buildings. Two compartmentalization techniques have been shown to be effective to this end: fire blocking, and draft stopping. The difference between the two is scale - fire blocking for small openings, and draft stopping for separating large assemblies. 66

Detailing for Fire Control Fire Blocking: Walls Balloon Framing 2x plates act as fireblock between wall and attic Continuous studs 2 or more stories 2x to fireblock stud space 2x fireblock between walls and floors Lack of fire blocking in balloon framing can quickly lead to catastrophic results, since flame can quickly climb through wall and floor cavities through chimney effect. Here are key locations to limit the spread of fire through the cavities of a balloon frame. 67

Detailing for Fire Control Fire Blocking: Walls Platform Framing 2x plates act as fireblock between wall and attic 2x plates act as fireblock between walls and floor 2x plates act as fireblock between wall and floor Platform framing offers a little more flame spread protection because of the platform nature of the framing. Here, continuity of the fire blocks is important. 68

Detailing for Fire Control Fire Blocking: Walls at Soffits Subfloor or underlayment 2x top plates Soffit 2x fireblock Fire blocks at soffit locations offer protection from flame spread into the soffit cavity. 69

Detailing for Fire Control Fire Blocking: Walls at Drop Ceiling Subfloor or underlayment 2x top plates Dropped ceiling 2x fireblock Similarly, fire blocks at the dropped ceiling level also serve the same protection. 70

Detailing for Fire Control Fire Blocking Walls: at Cove Ceiling Subfloor or underlayment 2x top plates Cove ceiling 2x fireblock as well as at ceiling coves. 71

Detailing for Fire Control Fire Blocking: Stairs 2x Fireblock at top and bottom between stringers To prevent fire from migrating into the joist spaces of floors, fire blocks should be located at the top and bottom of stair runs. Often framing headers serve this function. 72

Detailing for Fire Control Fire Blocking: Pipes Approved noncombustible firestop 2x Scab to reduce opening Plate Crevices around piping offer a sneaky way for fire to slip into a cavity. A fire block is needed here. 73

Detailing for Fire Control Fire Blocking: Chimneys Approved noncombustible fireblock Floor level A non-combustible fire block is to provided at all chimney openings to limit fire migration upward beside the chimney. 74

Detailing for Fire Control Draft Stopping: Single Family Dwellings Floor / Ceiling Floor Joists Draftstop Drop Ceiling Area on either side of draftstop is limited To prevent the spread of flame through assemblies, draft stopping is used. One application is compartmentalization of false or dropped ceilings into void volumes that are smaller so that fire is confined. 75

Detailing for Fire Control Draft Stopping: Single Family Dwellings Floor / Ceiling Draftstop Open-Web trusses Area on either side of draftstop is limited Drop Ceiling For trussed floors or ceilings, sheathing the truss will compartmentalize the void space into smaller volumes. 76

Detailing for Fire Control Draft Stopping: Multi-Family (2 or more) Dwellings Floor / Ceiling Ceiling joist Drop Ceiling Tenant separation wall Draftstop in line with tenant separation wall Draft stopping between dwelling units in the void space over tenant separation walls will also help to confine fire. 77

Detailing for Fire Control Draft Stopping: Multi-Family (2 or more) Dwellings In attic in line Floor / Ceiling with separation wall Tenant separation wall In mansard or overhang Also draft stopping the attic space in line over tenant separation walls will also compartmentalize the attic space into smaller volumes. 78

available from www.awc.org These documents are available free in HTML or PDF form from www.awc.org. Thank you! 79

Appendix - Test Data Appendix - Test Data 80

Beams Tested Designation Breadth (in) Depth (in) Specific Gravity F b-ult (psi) E x10 6 (psi) Resisting Moment (ft-lbs) Induced Moment (ft-lbs) TRADA 5.5 9.0 0.49 7,530 2.0 45,528 9,832 NFoPA 8.75 16.5 0.47 6,840 1.6 222,356 55,855 AF&PA-27 8.75 16.5 0.47 6,840 1.6 222,762 18,937 AF&PA-44 8.75 16.5 0.47 6,840 1.6 222,762 30,707 AF&PA-91 8.75 16.5 0.47 6,840 1.6 222,762 65,075 FCNSW1 5.9 16.5 0.82 28,485 2.7 621,507 74,789 FCNSW2 5.9 16.5 0.52 14,500 1.7 318,918 20,504 81

Columns tested in France Designation Depth (in) Breadth (in) Specific Gravity (lb/ft 3 ) F c-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Induced Load (lbs) CSTB44 7 7.875 0.56 2,565 1.6 132,365 39,790 CSTB45 7 7.875 0.56 2,565 1.6 132,365 39,790 82

Columns tested in Germany by Stanke et al. Designation Depth (in) Breadth (in) Specific Gravity F c-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Induced Load (lbs) R14A 5.5 5.5 0.44 7,368 2.5 84,644 19,026 R14B 5.5 5.5 0.45 7,929 2.3 80,310 19,026 R14C 5.5 5.5 0.45 8,131 2.4 82,217 9,524 R14D 5.5 5.5 0.43 7,447 2.2 75,740 14,264 H14A 5.5 5.5 0.44 8,050 2.0 70,825 19,026 H14B 5.5 5.5 0.48 7,652 2.4 82,598 19,026 H14C 5.5 5.5 0.45 8,131 2.4 82,217 9,524 H14D 5.5 5.5 0.43 7,447 2.2 75,740 14,264 H14/24A 5.5 9.5 0.41 6,243 1.7 99,126 32,628 H14/24B 5.5 9.5 0.41 6,169 1.6 98,033 32,628 H14/30A 5.5 11.75 0.45 6,914 1.7 130,414 40,786 H14/30B 5.5 11.75 0.47 8,690 2.7 198,238 20,393 H14/30C 5.5 11.75 0.46 7,165 1.8 134,828 20,393 83

Columns tested in Germany by Stanke et al. Designation Depth (in) Breadth (in) Specific Gravity F c-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Induced Load (lbs) H14/40 5.5 15.75 0.45 6,675 1.6 158,898 54,234 R15A 5.875 5.875 0.38 5,995 1.8 78,944 24,030 R15B 5.875 5.875 0.38 5,970 1.8 78,629 24,030 H15A 5.875 5.875 0.40 6,515 1.9 85,341 24,030 H15B 5.875 5.875 0.37 5,868 1.7 77,371 24,030 R16 5.875 5.875 0.31 4,302 1.3 72,417 29,432 H16A 6.25 6.25 0.37 5,723 1.7 94,688 29,432 H16B 6.25 6.25 0.40 6,595 1.9 108,172 29,432 R16/30 6.25 11.75 0.41 5,944 1.5 163,784 27,558 H16/30A 6.25 11.75 0.42 6,229 1.6 171,131 55,116 H16/30B 6.25 11.75 0.44 6,666 1.7 182,354 55,116 H16/30C 6.25 11.75 0.43 6,470 1.6 177,337 55,116 H16/30D 6.25 11.75 0.40 5,710 1.5 157,743 27,558 84

Columns tested in Germany by Stanke et al. Designation Depth (in) Breadth (in) Specific Gravity F c-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Induced Load (lbs) R20A 7.875 7.875 0.40 5,931 1.6 199,681 56,438 R20B 7.875 7.875 0.39 6,657 1.7 219,632 56,438 R20C 7.875 7.875 0.46 9,003 2.2 288,658 28,219 R20D 7.875 7.875 0.43 5,685 1.6 198,702 28,219 H20A 7.875 7.875 0.38 5,903 1.7 209,239 56,438 H20B 7.875 7.875 0.39 6,031 1.8 218,955 56,438 H20C 7.875 7.875 0.45 8,676 2.1 270,840 28,219 H20D 7.875 7.875 0.45 7,370 2.0 254,219 28,219 H20/40A 7.875 15.75 0.44 6,651 1.6 413,483 112,877 H20/40B 7.875 15.75 0.45 5,415 1.3 340,466 112,877 H24A 9.5 9.5 0.40 5,639 1.5 344,680 89,949 H24B 9.5 9.5 0.38 6,616 1.8 401,964 89,949 85

Columns tested in Germany by Stanke et al. Designation Depth (in) Breadth (in) Specific Gravity F c-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Induced Load (lbs) H26A 10.25 10.25 0.42 6,346 1.7 485,005 110,672 H26B 10.25 10.25 0.42 5,579 1.5 428,165 110,672 R27A 10.625 10.625 0.38 5,220 1.3 428,663 121,034 R27B 10.625 10.625 0.40 5,504 1.6 483,442 121,034 R27C 10.625 10.625 0.41 6,229 1.6 528,292 121,034 H27A 10.625 10.625 0.42 6,216 1.9 555,826 121,034 H27B 10.625 10.625 0.40 5,448 1.4 463,536 121,034 H27C 10.625 10.625 0.41 6,181 1.6 524,303 121,034 H28A 11.00 11.00 0.40 5,806 1.5 543,889 132,939 H28B 11.00 11.00 0.42 6,260 1.6 585,187 132,939 H40 15.75 15.75 0.41 5,659 1.4 1,257,232 308,647 86

Columns tested in England by Malhotra et al. Designation Depth (in) Breadth (in) Specific Gravity F c-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Induced Load (lbs) FR3 5.6 15.0 0.59 5,197 1.7 327,980 35,990 FP4 9.0 9.0 0.59 5,197 1.7 397,461 143,962 HR7 6.9 12.0 0.54 4,454 1.5 319,043 62,060 HP8 9.0 9.0 0.54 4,454 1.5 340,497 62,060 RR11 9.0 9.0 0.54 3,961 1.2 300,777 110,452 RP12 6.9 12.0 0.54 3,961 1.2 279,505 27,613 CR15 9.0 9.0 0.38 3,218 1.0 244,966 44,754 CP16 5.6 15.0 0.38 3,218 1.0 199,062 44,754 87

Tension Members Tested Designation Breadth (in) Depth (in) Specific 1 Gravity F t-ult (psi) E x10 6 (psi) Resisting Capacity (lbs) Tension Load (lbs) 4x6 Timber 3.38 5.31 0.49 2,132 1.4 38,223 3,194 5x9 Glulam 5.06 8.81 0.50 4,560 1.6 203,437 35,167 9x9 Glulam 8.56 8.75 0.50 4,560 1.6 341,644 19,580 1 Specific gravity estimated for grade and species 88

Measured and Calculated Decking Fire Resistance Times Designation Species Breadth (in) Depth (in) M induced M ult Measured t f (min) Calculated t f (min) UL #2 Douglas fir 5.5 1.5 0.16 24+ 25 UL #4 Douglas fir 5.5 1.5 0.21 18+ 23 HT1 Subalpine fir 1.625 3.625 0.07 62 58 HT2 Subalpine fir 1.625 3.625 0.07 56 58 HT3 Southern pine 5.625 2.625 0.15 54 53 HT4 Southern pine 5.625 2.625 0.15 NR 53 HT5 Southern pine 5.625 2.625 0.18 NR 49 HT6 Southern pine 5.625 2.625 0.18 45 49 NR = Not Reported 89

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