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Lateral Design of Wood Frame Structures

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Lateral Failure Shear Walls and Braced Walls

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Photos Courtesy National Information Service for Earthquake Engineering, University of California, Berkeley.

Lateral Failure

Earth Home

Shear Walls and Braced Walls

Shear Walls and Braced Walls

Photos Courtesy National Information Service for Earthquake Engineering, University of California, Berkeley. Photos Courtesy National Information Service for Earthquake Engineering, University of California, Berkeley.

Lateral Forces !

WIND - Wind forces are calculated from the velocity of the wind in that region and the load is stated in pounds per square foot.

Lateral Forces !

SEISMIC - Each region (Seismic Design Category, SDC) applies a multiplier to the structure’s mass in order to determine the lateral design load. ! The higher the SDC, the higher the multiplier.

– Racking – Sliding

– Overturning – Racking

Lateral Bracing

Lateral Bracing Shear Walls and Braced Walls

Shear Walls and Braced Walls

All buildings must have some type of lateral resisting system for lateral forces (wind, seismic).

Both Braced Walls and Shear Walls behave as a cantilevered beam.

1. 2. 3. 5.

Braced Walls Shear walls Prefabricated shear panel X-Bracing

Shear Wall/Braced Wall fixed at one end (at foundation)

Cantilever Beam fixed at one end

Shear Walls & Braced Walls

Shear Wall Analysis Methods

Shear Walls

Shear Walls

Shear Walls ! An Engineered Solution ! 

Pre-Fabricated or Field Fabricated

Braced Walls ! A prescriptive equivalent to engineered shear wall ! Braced Wall Lines ! Braced Wall Panels

Each Method requires: • Holdowns for uplift or overturning/ racking resistance • Anchor bolts for shear or translation

Shear Walls

Pre-Fabricated Shear Walls Shear Walls

Shear Walls

!  Manufacturer

provides allowable loads for a particular panel and installation !  Should compare cost differences to site built !  Install per manufacturer’s recommendation.

Site-Built Shear Walls !  Nailing

patterns and hardware attachment information provided by engineer. !  IBC Table 2306.4.1 Provides Nailing Information Courtesy of APA-The Engineered Wood Association!

Complete Exterior Sheathing CUREE’s 7 Steps to better Shearwalls

Building Better Shear walls CUREE came out with 7 Tips to building better shear walls as a result of their research.

Symmetrical Edge Nailing Pattern CUREE’s 7 Steps to better Shearwalls

!  Non-symmetrical !  Reduced

!  Damage

pattern shifts center of rotation of the panel

Capacity

concentrated at edges having single row of nails

Use Sill Plate Washers

Increase Nailing Edge Distance

CUREE’s 7 Steps to better Shearwalls

!  Plate

washers called for in the code as a result of sill plate splitting in cyclic testing performed at Virginia Tech !  Building code now requires 3” x 3” x ¼” Plate washers

CUREE’s 7 Steps to better Shearwalls

!  More

distance from edge equals better shear wall performance. !  Maintain ¾” at top and bottom of wall 5/8” on side framing member attachment

Avoid Over-Driving Nails into Sheathing

Use Larger Vertical Members CUREE’s 7 Steps to better Shearwalls

CUREE’s 7 Steps to better Shearwalls

!  Increase

vertical members or studs at holdowns and on sheathing joints !  Use

4x at holdowns !  Use 3x at vertical framing joints !  When

using a pneumatic nailer, avoid over-driving nails into sheathing !  Nail head should be recessed into sheathing a maximum of 1/32 inch

!  If

using built-up post, studs must be nailed together (stitch nailing) to ensure piece acts as single unit

Shear Walls & Braced Walls

Exceptions for Braced Wall Panel Length

Braced Walls

Shear Walls ! An Engineered Solution ! 

Pre-Fabricated or Field Fabricated

Braced Walls ! A prescriptive equivalent to engineered shear wall ! Braced Wall Lines ! Braced Wall Panels

Braced Walls

! 

Section R602.10.4 give exceptions if building contains: !  ! 

Continuous wood structural panel sheathing (R602.10.5) Alternate braced wall panels (R602.10.6.1 or R602.10.2)

PRESCRIPTIVE VS. ENGINEERED ! 

PRESCRIPTIVE ! 3 Stories Max. ! Wind < 110 mph (< 100 mph in hurricane-prone regions) ! SDC A-D ! Other limitations stated in IRC Chapter 3

! 

ENGINEERED ! Any size/shape within IBC limits ! Wind – no limit ! Seismic – no limit ! Governed by engineer’s calculations

“Cookbook Engineering” ! 

!  Recipes

! ! ! ! !

BRACED WALL REQUIREMENTS HAVE BEEN COMPLETELY REWRITTEN

! 2006 IRC © = 6 pages ! 2009 IRC © and 2012 IRC © = 28 pages ! ICC / APA Guide to the 2009 IRC© Bracing Provisions = 255 pages ! 

! !

based on: Historical Performance Typical Materials Conservative Analysis Nationwide Application No Design Professional Required

Braced Walls in the 2012 IRC ©

2012 IRC & 2009 IRC vs. 2006 IRC ! 

Ad Hoc Wall Bracing Committee

ALL PLANS DESIGNED UNDER 2006 IRC © SHOULD BE REVIEWED Most smaller houses will likely be OK Larger houses may need additional bracing.

! Continuous improvement to the organization of BW requirements ! Reorganized to consolidate BWL length, spacing and orientation into ! ! ! ! ! !

one section BWP now allowed to be up to 10ft from end of BWL instead of 12.5ft Wind adjustment footnotes have now been consolidated into a table Bracing methods consolidated into one section Minimum BWP lengths consolidated into one table All ABW now consolidated into one section Simplified BW section added for low wind and low seismic areas.

BRACED WALL TERMINOLOGY ! ! ! !

BRACED WALL LINE SPACING

Braced Wall Line Braced Wall Line Spacing Braced Wall Panel Braced Wall Panel Spacing

– The braced wall line spacing in IRC Table R602.10.1.3 Seismic>Do is limited to 25 feet or less, however: – For townhouses in SDC C - No adjustment required for spacing up to 35 feet, bracing length Table R602.10.1.3. Note that IRC Section R301.2.2 exempts all residential buildings in SDC A and B from seismic provisions of the code. – For all structures in SDC D0, D1, D2, - No adjustment required for spacing up to 35 feet to accommodate a single room not to exceed 900 square feet in each dwelling unit, otherwise braced wall line lengths should be adjusted in accordance with IRC Table R602.10.1.3, with certain limitations. Braced wall line spacing greater than 35 feet is not permitted.

BRACED WALLS OFFSET

TABLE R602.10.1.3 BRACED WALL LINE SPACING

BRACED WALL LINE SPACING CRITERIA APPLICATION

CONDITION

BUILDING TYPE Maximum Spacing

Wind Bracing

Seismic Bracing

Exception to Maximum Spacing

85 mph to < 110 mph

Detached, Townhouse

SDC A - C

Detached

Use Wind Bracing

SDC A - B

Townhouse

Use Wind Bracing

SDC C

Townhouse

35 feet

Up to 50 feet when length of required bracing per Table R602.10.3(3) is adjusted in accordance with Table R602.10.3(4).

SDC D0, D1, and D2

Detached, Townhouses, One- and Two-Story Only

25 feet

Up to 35 feet to allow for a single room not to exceed 900 square feet. Spacing of all other braced wall lines shall not exceed 25 feet.

SDC D0, D1, and D2

Detached, Townhouse

25 feet

Up to 35 feet when length of required bracing per Table R602.10.3(3) is adjusted in accordance with Table R602.10.3(4).

For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 mile per hour = 0.447 m/s.

60 feet

None

•  BRACED

WALL PANELS are allowed to be offset up to 8’-0” and still be considered in the same BRACED WALL LINE so long as all of the BRACED WALL PANELS are within 4’-0” of the designated BRACED WALL LINE.

BRACED WALL LINE SPACING ! !

LENGTH OF BRACED WALL LINES

IRC Section R602.10.1 The length of the braced wall line spacing shall be measured as the maximum distance to adjacent braced wall lines.

! !

LENGTH OF BRACED WALL LINES

! 

LENGTH OF BRACED WALL LINES

R602.010.1 BRACED WALL LINES:

The end of a braced wall line shall be considered to be either: !  The intersection with perpendicular exterior walls !  The intersection with perpendicular – 1 braced wall lines !  The end of the braced wall line shall be chosen such that the – 2 maximum length results

! 

– 3

IRC Section R602.10.1 The length of a braced wall line shall be measured as the distance between the ends of the wall line.

! 

R602.010.1 BRACED WALL LINES:

! 

The end of a braced wall line shall be considered to be either: The intersection with perpendicular exterior walls The intersection with perpendicular braced wall lines The end of the braced wall line shall be chosen such that the maximum length results

! 

– 1 !  ! 

– 2

– 3

IMAGINARY (EFFECTIVE) BRACED WALL LINES !

BRACED WALL LINE LENGTH EXAMPLE

If wall line is less than 4 feet from braced wall line there is no need for a bracing panel on that line. – The braced wall line spacing in IRC Table R602.10.1.2 (2) is limited to 25 feet or less, however: – For townhouses in SDC C - No adjustment required for spacing up to 35 feet, bracing length Table R602.10.1.2 (3). Note that IRC Section R301.2.2 exempts all residential buildings in SDC A and B from seismic provisions of the code. – For all structures in SDC D0, D1,, D2, - No adjustment required for spacing up to 35 feet to accommodate a single room not to exceed 900 square feet in each dwelling unit, otherwise braced wall line lengths should be adjusted in accordance with IRC Table R602.10.1.5, with certain limitations. Braced wall line spacing greater than 35 feet is not permitted.

BRACED WALL PANEL SPACING !

BRACED WALL PANEL (PRESCRIBED)

IRC Section R602.10.1.4 !

Not Farther Than 25 Feet on Center !

Measured From Centerline of Panel to Centerline of Panel

!

If Bracing Sections are Wider Than 4 Feet it is Acceptable to be Spaced 21 Feet Apart

!

Seismic and Wind Requirements Slightly Different

!

A full-height section of wall constructed to resist in-plane shear loads through interaction of framing members sheathing material and anchors.

!

The panel’s length meets the requirements of its particular bracing method and contributes toward the total amount of bracing required along its braced wall line in accordance with Section R602.10.1.

INTERMITTENT BRACING !

LIB – LET-IN-BRACING

!

DWB – DIAGONAL WOOD BOARDS

!

WSP – WOOD STRUCTURAL PANEL

!

SFB – STRUCTURAL FIBERBOARD SHEATHING

!

GB – GYPSUM BOARD

!

PBS – PARTICLEBOARD SHEATHING

!

PCP – PORTLAND CEMENT PLASTER

!

HPS – HARDBOARD PANEL SIDING

!

ABW – ALTERNATE BRACED WALL

!

PFH – PORTAL FRAME WITH HOLDOWNS

!

PFG – PORTAL FRAME AT GARAGE.

LIB – LET-IN-BRACING Method

Material

Minimum Thickness

LIB

Let-In Bracing

1x4 wood or approved metal straps at 45 to 60 angles for maximum 16” stud spacing

DWB – DIAGONAL WOOD BOARDS Method

Material

Minimum Thickness

DWB

Diagonal Wood Boards

3/4” (1” nominal) for maximum 24” stud spacing

Figure

Figure

Connection Criteria

Wood: 2-8d nails per stud including top & bottom plate Metal: per manufacturer

WSP – WOOD STRUCTURAL PANEL

Connection Criteria

Method

Material

Minimum Thickness

2-8d (2 1/2” x 0.113”) nails or 2 staples, 1-3/4” per stud

WSP

Wood Structural Panel (See Section R604)

3/8”

Figure

Connection Criteria

Exterior Sheathing: see IRC Table R602.3(3) Interior Sheathing: see IRC Table R602.3(1)

SFB – STRUCTURAL FIBERBOARD SHEATHING Method

Material

Minimum Thickness

SFB

Structural Fiberboard Sheathing

1/2” or 25/32” for Maximum 16” Stud spacing

Figure

Connection Criteria

1-1/2” galvanized roofing nails or 8d common (2-1/2” x 0.131”) nails at 3” spacing (panel edges) at 6” spacing (intermediate supports).

GB – GYPSUM BOARD Method

GB

Material

Gypsum Board

Material

Minimum Thickness

PBS

Particleboard Sheathing (See Section R605)

3/8” or 1/2” for maximum 16” stud spacing

Figure

Figure

Connection Criteria

Nails and screws at 7” spacing at panel edges including top and bottom plates for all braced wall panel locations. For exterior sheathing nail or screw size, see IRC Table R602.3(1). For interior gypsum board nail or screw size, see IRC Table R702.3.5.

1/2”

PCP – PORTLAND CEMENT PLASTER

PBS – PARTICLEBOARD SHEATHING Method

Minimum Thickness

Connection Criteria

Method

Material

Minimum Thickness

1-1/2” galvanized roofing nails or 8d common (2-1/2” x 0.131”) nails at 3” spacing (panel edges) at 6” spacing (intermediate supports).

PCP

Portland Cement Plaster

See Section R703.6 for maximum 16” stud spacing

Figure

Connection Criteria

1-1/2”, 11 gage 7/16” head nails or 7/8”, 16 gage staples at 6” spacing

CONTINUOUS SHEATHING

HPS – HARDBOARD PANEL SIDING

Method

Material

Minimum Thickness

HPS

Hardboard Panel Siding

7/16” for maximum 16” stud spacing

Figure

Connection Criteria

!

0.092” dia., 0.225 head nails with length to accommodate 1-1/2” penetration into studs at 4” spacing (panel edges), at 8” spacing (intermediate supports).

CONTINUOUS SHEATHING BRACING MATERIALS ! ! ! !

CS-WSP CS-G CS-PF CS-SFB

CS-WSP CONTINUOUSLY SHEATHED WOOD STRUCTURAL PANEL

Method

CS-WSP

Method

Material

Minimum Thickness

CS-WSP

Wood Structural Panel

3/8”

6d common (2” x 0.113”) nails at 6” spacing (panel edges) and at 12” spacing (intermediate supports) or 16 ga. x 1-3/4 staples: at 3” spacing (panel edges) and 6” spacing (intermediate supports)

CS-G

Wood Structural Panel Adjacent to Garage Openings and Supporting Roof Load Only ab

3/8”

See Method CS-WSP

CS-PF

Continuous Portal Frame

See Section R602.10.4.1.1

See Section R602.10.4.1.1

a. Applies to one wall of a garage only. b. Roof covering dead loads shall be 3 psf or less.

Structural Sheathing Applied to all Sheathable Surfaces Including the Areas Above and Below Openings

Figure

Connection Criteria

Material

Wood Structural Panel

Minimum Thickness

3/8”

Figure

Connection Criteria

6d common (2” x 0.113”) nails at 6” spacing (panel edges) and at 12” spacing (intermediate supports) or 16 ga. x 1-3/4 staples: at 3” spacing (panel edges) and 6” spacing (intermediate supports)

CS-G

CS-PF

CONTINUOUSLY SHEATHED WOOD STRUCTURAL PANEL ADJACENT TO GARAGE

CONTINUOUSLY SHEATHED PORTAL FRAME

Method

Material

Minimum Thickness

CS-G

Wood Structural Panel Adjacent to Garage Openings and Supporting Roof Load Only ab

3/8”

Figure

Connection Criteria

See Method CS-WSP

Method

Material

Minimum Thickness

CS-PF

Continuous Portal Frame

See Section R602.10.4.1.1

Figure

Connection Criteria

See Section R602.10.4.1.1

a. Applies to one wall of a garage only. b. Roof covering dead loads shall be 3 psf or less.

CS-SFB

MIXED BRACING METHODS

CONTINUOUSLY SHEATHED STRUCTURAL FIBERBOARD SHEATHING

Method

CS-SFB

! !

Material

Continuous Structural Fiberboard Sheathing

Minimum Thickness

1/2” or 25/32” for 16” Stud Spacing Only

New to the 2009 IRC Restrictions apply, see R602.10.5

Figure

Connection Criteria

1-1/2” galvanized roofing nails or 8d common (2-1/2” x 0.131”) nails at 3” spacing (panel edges) at 6” spacing (intermediate supports).

! ! !

!

R602.10.1.1 BRACED WALL PANELS. ! Mixing of bracing methods shall be permitted as follows: 1. Mixing bracing methods from story to story is permitted. 2. Mixing bracing methods from braced wall line to braced wall line within a story is permitted, except CS shall conform to R602.10.4 and R602.10.5. 3. Mixing bracing methods within a braced wall line is permitted only in SDC A, B and detached dwellings of C.

Table R602.10.4.1.1

ABW – ALTERNATE BRACED WALL Method

ABW

Material

Minimum Thickness

Wood Structural Panel

Figure

Tension Strap Capacity Required For Resisting Wind Pressures Perpendicular to 6:1 Aspect Ratio Walls

Connection Criteria MINIMUM WALL STUD FRAMING SIZE AND GRADE

3/8”

BASIC WIND SPEED (mph)

MAXIMUM PONY WALL HEIGHT (feet)

MAXIMUM TOTAL WALL HEIGHT (feet)

MAXIMUM OPENING WIDTH (feet)

85

0

10

18

1000

1000

1000

1000

1000

9

1000

1000

1000

1000

1000

10

16

1000

1000

1750

1800

2325

3500

18

1000

1200

2100

2175

2725

Engineering Req’d

– 8d common or gal. box nails@ 6" o.c. at panel edges for the first two stories

– Studs under header as required

1

2X4 No. 2 Grade

– 8d common or gal. box nails @ 12" o.c. at interior supports

– Hold-down or strap-type anchor per Table R602.10.3.2 (Both shown for clarity.) Strap-type anchors shall be permitted to be attached over the wood structural panel.

– Minimum reinforcing of foundation, one #4 bar top and bottom of footing. Reinforcing shall be lapped 15 inches.

2

2

– (2) 1/2" Diameter anchor bolts per Figure R403.1.1, located between 6 and 12 inches of each end of the segment

– Minimum footing size under opening is 12" x 12" A turneddown slab shall be permitted at door openings. Reinforcing shall be as shown above.

4

2

10

12

12

12

2x6 Stud Grade 4

Table R602.10.3.2 Minimum Length Requirements and Hold-Down Forces For ABW Braced Wall Panels

85

90

100

Exposure C

Tension strap capacity required (lbf)

– For panel splice (if needed) adjoining panel edges shall meet over and be fastened to common framing

– Minimum 2X4 framing, minimum double studs required

100

Exposure B

See Section R602.10.3.2

– Min. 3/8" (10) wood structural panel sheathing on one face

90

12

1000 1275

9

1000

1000

1025

1075

1550

2500

16

1525

2025

3125

3200

3900

Engineering Req’d

18

1875

2400

3575

3700

Engineering Req’d

Engineering Req’d

9

1000

1200

2075

2125

2750

4000

16

2600

3200

Engineering Req’d

Engineering Req’d

Engineering Req’d

Engineering Req’d

18

3175

3850

Engineering Req’d

Engineering Req’d

Engineering Req’d

Engineering Req’d

9

1775

2350

3500

3550

Engineering Req’d

Engineering Req’d

16

4175

Engineering Req’d

Engineering Req’d

Engineering Req’d

Engineering Req’d

Engineering Req’d

9

1000

1000

1325

1375

1750

2550

16

1650

2050

2925

3000

3550

Engineering Req’d

18

2025

2450

3425

3500

4100

Engineering Req’d

9

1125

1500

2225

2275

2775

3800

16

2650

3150

Engineering Req’d

Engineering Req’d

Engineering Req’d

Engineering Req’d

18

3125

3675

Engineering Req’d

Engineering Req’d

Engineering Req’d

Engineering Req’d

Bracing Around Garage Doors Braced Walls

Lateral Failure SEISMIC DESIGN CATEGORY AND WIND SPEED

HEIGHT OF BRACED WALL PANEL

Minimum sheathed length

SDC A, B and C Wind speed < 110 mph

R602.10.3.2, item 1 hold-down force (lb) R602.10.3.2, item 1 hold-down force (lb) Minimum sheathed length R602.10.3.2, item 1 hold-down force (lb)

SDC D0, D1 and D2 Wind speed < 110 mph

R602.10.3.2, item 1 hold-down force (lb)

8 ft

9 ft

10 ft

11 ft

12 ft

2’-4”

2’-8”

2’-10”

3’-2”

3’-6”

1800

1800

1800

2000

2200

3000

3000

3000

3300

3600

2’-8”

2’-8”

2’-10”

Not Permitted

Not Permitted

1800

1800

1800

Not Permitted

Not Permitted

3000

3000

3000

Not Permitted

Not Permitted

Photo Courtesy National Information Service for Earthquake Engineering, University of California, Berkeley.

PFH – PORTAL FRAME WITH HOLDOWNS

PFG – PORTAL FRAME AT GARAGE EIGHT SPECIFIC PFG PROVISIONS R602.10.3.4

Method

Material

Minimum Thickness

PFG

Wood Structural Panel

7/16”

Figure

Connection Criteria

Method

Material

Minimum Thickness

See Section R602.10.3.4

PFH

Wood Structural Panel

3/8”

– Fasten sheathing to header with 8d common or galvanized box nails in 3 in. grid pattern as shown and 3 in. o.c. in all framing (studs, blocking, and sills) typ.

– 1

– For a panel splice (if needed), panel edges shall occur over and be nailed to common blocking, and occur within middle 24 in. of wall height. One row of 3 in. o.c. nailing is required in each panel edge.

– 2

– Minimum length based on 4:1 height-to-length ratio. For example: 24 in. min. for 8 ft. height.

– 3

See Section R602.10.3.3

– Fasten sheathing to header with 8d common or galvanized box nails in 3 in. grid pattern as shown and 3 in. o.c. in all framing (studs, blocking, and sills) typ.

– 2

– 3

– Min. length = 16 in. for one story, min. length = 24 in. for use in the first two story structures.

– 4

– Min. 4200 lb tie-down device (embedded into concrete and nailed into framing). – For a panel splice (if needed), panel edges shall occur over and be nailed to common blocking, and occur within middle 24 in. of wall height. One row of 3 in. o.c. nailing is required in each panel edge.

CONTINUOUSLY SHEATHED BRACED WALL LINE A braced wall line with structural sheathing applied to all sheathable surfaces including the areas above and below openings.

Connection Criteria

– Fasten top plate to header with two rows of 16d sinker. Nails at 3 in. o.c. typ.

– 1

– 5

!

Figure

CONTINUOUSLY SHEATHED BRACED WALL WITH OPENINGS !

R602.10.4.2 OPENINGS IN BRACED WALL LINE

CONTINUOUSLY SHEATHED BRACED WALL WITH OPENINGS !

R602.10.4.2 OPENINGS IN BRACED WALL LINE

– TABLE R602.10.5

!

CS - MINIMUM LENGTH OF BRACED WALL PANELS

WALL HEIGHT Method

Adjacent Clear Opening Height

8’

9’

10’

11’

12’

64”

24”

27”

30”

33”

36”

68”

26”

27”

30”

33”

36”

72”

27”

27”

30”

33”

36”

76”

30”

29’

30”

33”

36”

80”

32”

30”

30”

33”

36”

84”

35”

32”

32”

33”

36”

88”

38”

35”

33”

33”

36”

92”

43”

37”

35”

35”

36”

96”

48”

41”

38”

36”

36”

100”

-

44”

40”

38”

38”

104”

-

49”

43”

40”

39”

108”

-

54”

46”

43”

41”

112”

-

-

50”

45”

43”

116”

-

-

55”

48”

45”

120”

-

-

60”

52”

48”

124”

-

-

-

56”

51”

128”

-

-

-

61”

54”

132”

-

-

-

66”

58”

136”

-

-

-

-

62”

140”

-

-

-

-

66”

144”

-

-

-

-

72”

CS-G

See Note B

24”

27”

30”

-

-

CS-PF

< 120”

16”

18”

20”

-

-

CS-WSP, CS-SFB

a. Interpolation shall be permitted. b. Garage openings adjacent to a method CS-G panel shall be provided with a header in accordance with IRC Table R502.5(1). A full-height clear opening shall not be permitted adjacent to a method CS-G c. Maximum opening height shall be in accordance with IRC Figure R602.10.4.1.1.

CONTINUOUSLY SHEATHED BRACED WALL WITH OPENINGS R602.10.4.2 OPENINGS IN BRACED WALL LINE

EXAMPLE PROBLEM

Example 1 – Upper Level

EXAMPLE PROBLEM 1 ! 

Single Family

! 

Two Story

! 

SDC = C

! 

Wind =100 MPH, Exposure C

! 

Roof Eave-to-Ridge = 8 ft

! 

Roof/Ceiling Dead Load = 20 psf

! 

Wall Dead Load = 8 psf

! 

Wall Heights: 10 ft

2012 IRC - WIND

TABLE R602.10.3(2) WIND ADJUSTMENT FACTORS TO THE REQUIRED LENGTH OF WALL BRACING

!

BASIC WIND SPEED 5

1.00 1.30 1.45 1.60

Additional 800-Pound Hold-Down Device

Top Story Only

Fastened to the end studs of each braced wall panel and to the foundation or framing below.

0.80

DWB, WSP, SFB, PBS, PCP, HPS

Interior Gypsum Board Finish (or Equivalent)

Any Story

Omitted from inside face of braced wall panels

1.40

DWB, WSP, SFB, PBS, PCP, HPS, CS-WSP, CS-G, CS-SFB

Gypsum Board Fastening

Any Story

4 inches o.c. at panel edges, including top and bottom plates, and all horizontal joints blocked

0.70

GB

APPLICABLE METHODS

All Methods

For SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 pound = 4.48 N. a. Linear interpolation shall be permitted. b. The total adjustment factor is the product of all applicable adjustment factors. c. The adjust factor is permitted to be 1.0 when determining bracing amounts for intermediate braced wall lines provided the bracing amounts on adjacent braced wall lines are based on a spacing and number that neglects the intermediate braced wall line.

2012 IRC - WIND

TABLE R602.10.3(2) WIND ADJUSTMENT FACTORS TO THE REQUIRED LENGTH OF WALL BRACING

!

BASIC WIND SPEED 5

1.00 1.30 1.45 1.60

Additional 800-Pound Hold-Down Device

Top Story Only

Fastened to the end studs of each braced wall panel and to the foundation or framing below.

0.80

DWB, WSP, SFB, PBS, PCP, HPS

ABW

Interior Gypsum Board Finish (or Equivalent)

Omitted from inside face of braced wall panels

1.40

DWB, WSP, SFB, PBS, PCP, HPS, CS-WSP, CS-G, CS-SFB

PFH

Any Story

Gypsum Board Fastening

Any Story

4 inches o.c. at panel edges, including top and bottom plates, and all horizontal joints blocked

APPLICABLE METHODS MINIMUM LENGTH a

METHOD (See Table R602.10.4)

All Methods

CONTRIBUTING LENGTH (inches)

9 Feet

10 Feet

11 Feet

12 Feet

DWB, WSP, SFB, PBS, PCP, HPS, BV-WSP

48

48

48

53

58

Actual b

GB

48

48

48

53

58

Double Sided = Actual Single Sided + 0.5 x Actual Actual b

LIB

0.70

Wall Height 8 Feet

55

62

69

NP

NP

SDC A, B, and C wind speed = < 110 mph

28

32

34

38

42

SDC D0, D1, and D2 Wind speed < 110 mph

28

32

34

NP

NP

Supporting Roof Only

16

16

16

18c

20c

Supporting One Story & Roof

24

24

24

27c

29c

48

PFG

24

27

30

33d

36d

1.5 x Actual b

CS-G

24

27

30

33

36

Actual b

CS-PF

16

18

20

22e

24e

Actual b

48

48

GB

For SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 pound = 4.48 N. a. Linear interpolation shall be permitted. b. The total adjustment factor is the product of all applicable adjustment factors. c. The adjust factor is permitted to be 1.0 when determining bracing amounts for intermediate braced wall lines provided the bracing amounts on adjacent braced wall lines are based on a spacing and number that neglects the intermediate braced wall line.

This concludes The American Institute of Architects Continuing Education Systems Course!

Todd Grevious! (952)898-8651! [email protected]!

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.45 N, 1 mile per hour = 0.447 m/s. NP = Not Permitted a. Linear interpolation shall be permitted. b. Use the actual length when it is greater than or equal to the minimum length. c. Maximum header height for PFH is 10 feet in accordance with Figure R602.10.6.2 but wall height may be increased to 12 feet with pony wall. d. Maximum opening height for PFG is 10 feet in accordance with Figure R602.10.6.3 but wall height may be increased to 12 feet with pony wall. e. Maximum opening height for CS-PF is 10 feet in accordance with Figure R602.10.6.4 but wall height may be increased to 12 feet with pony wall.