1. 2182 D - Timber Framing Code
Wall Bracing
Class Exercise 1

2. Floor Plan from Exercise 1. AS 1684 .2 (2006) Non Cyclonic Code.
Reference Material
Class Exercise 1 Roofing & Wall Framing notes.
Floor Plan from Exercise 1.
AS (2006) Non Cyclonic Code.

4. (a) Determine the wind classification (b) Determine the wind pressure
Refer to page 112 – Section 8 – AS
General
Bracing shall be designed and provided for each storey of the house and for the subfloor, where required, in accordance with the following procedure:
(a) Determine the wind classification
(b) Determine the wind pressure
(c) Determine area of elevation
(d) Calculate racking force
= N3

5. 8.3.2 Wind pressure on the building
Refer to page 112 – Section 8 – AS
Wind pressure on the building
Wind pressures on the surfaces of the building depend on the wind classification, width of building and roof pitch. Tables 8.1 to 8.5 give pressures depending on these variables.
(AS , pages 116 – 124)
Pressures are given for single storey and upper storey of two storeys for both long and short sides of the building, and lower storey of two storeys or subfloor for both long and short sides of the building.

6. Refer to page 112 – Section 8 – AS 1684.2
Area of elevation
The wind direction used shall be that resulting in the greatest load for the length and width of the building, respectively.
As wind can blow from any direction, the elevation used shall be that for the worst direction.

7. Permanent Wind Bracing
Length of Building
Width of Building
Roof Pitch Rise of Roof
Floor to ceiling height
Wind Classification
Permanent Wind Bracing
14.640
7.570
300
2.100m
2.700m N3
Using the Plan & previous information from Roof and Wall framing
Calculations fill in the above information
(7.570 ÷ 2) – = 3.635
3.635 × tan 30 = 2.098
Rise = 2.100m

8. Wind Direction 2
Wind Direction 1

9. Calculate the area of elevation for Wind Direction 1
3 785
7 070
14 640
2 100
1 350
x = m2
7 070 x = m2
3 785 x = m2
Total Area m2

10. Refer to page 116 – Section 8 – AS 1684.2
Racking force
The total racking force for each storey or level of the building shall be the product of the projected area of elevation of the building multiplied by the lateral wind pressure determined from Tables 8.1 to 8.5. The racking force shall be calculated for both directions (long and short sides) of the building.
Table 8.2 is used for determining the pressure on single or upper storey elevations where the wind direction is at 90O to a ridge and for wind speeds N1, N2, N3 & N4.

11. Projected area of elevation (m2)
Racking force
The total racking force, in kN, shall be calculated as follows:
Projected area of elevation (m2) X
Lateral wind pressure (kPa) =
Total racking force

12. Pressure / kPa = 1.1 Wind Direction 1 Wind Speed / N3 Roof Pitch 300
Building Width
Pressure / kPa
= 1.1

13. Projected area of elevation
Racking force
The total racking force, in kN, shall be calculated as follows:
Projected area of elevation
(42.6m2) X
Lateral wind pressure
(1.1kPa)
= Total racking force
(46.9kN) – Wind Direction 1

14. Side elevation (Wind direction 1)
Area m2
Wind Pressure kPa (table 8.2 p 118)
Total Racking Force KN
Nominal Bracing KN
Bracing Required KN
42.6
1.1
46.9
Fill in known information (Area, Pressure, Raking Force)
Calculate Nominal Bracing

15. Refer to page 140 – Section 8 – AS 1684.2
 Nominal wall bracing
Nominal wall bracing is wall framing lined with sheet materials such as plywood, plasterboard, fibre cement or hardboard, or the like, with the wall frames nominally fixed to the floor and the roof or ceiling frame.
The maximum amount that can be resisted by nominal wall bracing is 50% of the total racking forces determined from Clause 8.3.4 . Nominal wall bracing shall be evenly distributed throughout the building. If this is not the case, the contribution of nominal bracing shall be ignored.
The minimum length of nominal bracing walls shall be 450 mm.

16. 8.3.6.2  Nominal wall bracing (Cont.)
The bracing capacity of nominal bracing is scheduled in Table 8.17.

17. Wind Direction 1
Calculate all single sided (Gyprock lined) walls for Nominal Bracing
2 x (7.570 – 0.480) + (2 x 1.100) = m
x 0.45kN/m = 7.4kN
Now Calculate double or Two Sided (Gyprock Lined) Walls

18. Wind Direction 1
Two Sided walls for Nominal Bracing
(4 x 2.500) + (1 x 2.400) + (1 x 3.500) + (2 x 0.500) = m
x 0.75kN/m = 12.7kN

19. Side elevation (Wind direction 1)
Area m2
Wind Pressure kPa (table 8.2 p 118)
Total Raking Force KN
Nominal Bracing KN
Bracing Required KN
42.6
1.1
46.9 20
26.9
Fill in Nominal Bracing total of Single & Two Sided walls
= kN
Check that nominal bracing is 50% or less than total racking force
Bracing required = Total Racking Force – Nominal Bracing.
46.9 – 20 = 26.9kN of Bracing Required.

20. 8.3.6.6 Location and distribution of bracing
Refer to page 148 – Section 8 – AS
Location and distribution of bracing
Bracing shall be approximately evenly distributed and shall be provided in both directions (see Figure 8.5).
Bracing shall initially be placed in external walls and where possible at the corners of the building.
Figure 8.5 Location of Bracing

21. Select Bracing Bracing Type ‘G’ Method B (p 144)
Method B = 6.0 KN/m x 1.2m (sheet width)
1 Sheet = 7.2KN Therefore 4 x 7.2 = 28.8 KN
Reference, Location and distribution of bracing
Check bracing required to amount of ‘G’ type bracing.
26.9kN Required & 28.8kN given in type ‘G’.
4 Type ‘G’ sheets will meet the requirements.

22. Bracing Type ‘G’ – Table 8.18 page 144 AS 1684.2 - 2006

23. Wind Direction 1
Mark Plan with Bracing Sheets to support Wind Direction 1

24. 8.3.6.6 Location and distribution of bracing
Refer to page 148 – Section 8 – AS
Location and distribution of bracing
Bracing shall be approximately evenly distributed and shall be provided in both directions (see Figure 8.5).
Bracing shall initially be placed in external walls and where possible at the corners of the building.
Figure 8.5 Location of Bracing

25. Calculate spacing of Bracing for Wind Direction 2
Refer page 150 of (2006)
Wind Speed
Ceiling Width
Roof Pitch
Spacing of
Bracing
Calculate spacing of Bracing for Wind Direction 2

26. Wind Direction 1
Braces are too far apart. We must place intermediate braces < 6.1m apart

27. Wind Direction 1
Braces are too far apart. We must place intermediate braces < 6.1m apart

28. Repeat for Wind Direction 2

29. Calculate the area of elevation for Wind Direction 2
3 785
7 570
2 100
1 350
7 570 x = m2
3 785 x = m2
Total Area m2

30. Wind Direction 2 Wind Speed Roof Pitch Building Width Pressure / kPa
Refer page 122
of (2006)
Wind Direction 2
Wind Speed
Roof Pitch
Building Width
Pressure / kPa
1.2kPa

31. Projected area of elevation
Racking force
The total racking force, in kN, shall be calculated as follows:
Projected area of elevation
(18.1m2) X
Lateral wind pressure
(1.2kPa)
= Total racking force
(21.7kN) – Wind Direction 2

32. End elevation (Wind direction 2)
Area m2
Wind Pressure kPa (table 8.4 p 122)
Total Racking Force KN
Nominal Bracing KN
Bracing Required KN
18.1
1.2
21.7
Fill in known information (Area, Pressure, Raking Force)
Calculate Nominal Bracing

33. Refer to window schedule for window sizes
Wind Direction 2
Calculate all single sided (Gyprock lined) walls for Nominal Bracing
2 x ( – 0.480) = m
– openings = nominal S/S length
Refer to window schedule for window sizes

34. Total length of opening widths = 16.150
Window Schedule:
Window W x H
W9 Bedroom
W1 Bedroom
W8 Bedroom
W2 Bath & WC
W3 Laundry
W4 Kitchen
W5 Dining
W6 Living
W7 Family
D2 Entry
D1 Kitchen
Total length of opening widths =

35. Wind Direction 2 28.320 – openings = nominal S/S length
x 0.45kN/m = 5.477kN
Now Calculate double or Two Sided (Gyprock Lined) Walls

36. Wind Direction 2 Two Sided walls for Nominal Bracing
( ) – = – 4.500
= m
x 0.75kN/m = 8.483kN

37. End elevation (Wind direction 2)
Area m2
Wind Pressure kPa (table 8.4 p 122)
Total Racking Force KN
Nominal Bracing KN
Bracing Required KN
18.1
1.2
21.7
10.85
10.85
Fill in Nominal Bracing total of Single & Two Sided walls
= kN
Check that nominal bracing is 50% or less than total raking force
Nominal Bracing is over 50% - Therefore Total raking force is to be halved
21.7 ÷ 2 = kN

38. 8.3.6.6 Location and distribution of bracing
Refer to page 148 – Section 8 – AS
Location and distribution of bracing
Bracing shall be approximately evenly distributed and shall be provided in both directions (see Figure 8.5).
Bracing shall initially be placed in external walls and where possible at the corners of the building.
Figure 8.5 Location of Bracing

39. Calculate spacing of Bracing for Wind Direction 2
Refer page 150 of (2006)
Wind Speed
Ceiling Width
Roof Pitch
Spacing of
Bracing
Calculate spacing of Bracing for Wind Direction 2

40. Select Bracing Bracing Type ‘G’ Method B (p 144)
Method B = 6.0 KN/m x 1.2m (sheet width)
1 Sheet = 7.2KN - Therefore 2 x 7.2 = 14.4 kN
14.4 kN Meets the racking force requirement, but does not meet the
requirements of clauses & , Therefore those requirements
need to be met.
Braces need to start at the corners and no further apart than 6.700m
maximum Spacings to Wind Direction 2
Mark braces on floor plan.

41. Wind Direction 2
Bracing for Wind Direction 2 complete.

42. Select Bracing Bracing Type ‘G’ Method B (p 144)
Method B = 6.0 KN/m x 1.2m (sheet width)
1 Sheet = 7.2KN - Therefore 2 x 7.2 = 14.4 kN
Refer to pg 148: panel length 600 equals strength of 900
Divided by two. i.e. .9 x 6Kn/m= 5.4 / 2=2.7
(3 x 2.7) + (.9 x 6kN) = 20.7
Braces need to start at the corners and no further apart than 6.700m
maximum Spacings to Wind Direction 2
Mark braces on floor plan.

43. Wind Direction 2
Bracing for Wind Direction 2 complete.

44. Exercise 1 Completed