2182 D - Timber Framing Code Wall Bracing Class Exercise 1

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 1684 .2 (2006) Non Cyclonic Code.

(a) Determine the wind classification (b) Determine the wind pressure Refer to page 112 – Section 8 – AS 1684.2 8.3.1 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

8.3.2 Wind pressure on the building Refer to page 112 – Section 8 – AS 1684.2 8.3.2 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 1684.2, 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.

Refer to page 112 – Section 8 – AS 1684.2 8.3.3 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.

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) – 0.150 = 3.635 3.635 × tan 30 = 2.098 Rise = 2.100m

Wind Direction 2 Wind Direction 1

Calculate the area of elevation for Wind Direction 1 3 785 7 070 14 640 2 100 1 350 14 640 x 1 350 = 19.764 m2 7 070 x 2 100 = 14.847m2 3 785 x 2 100 = 7.949 m2 Total Area 42.56 m2

Refer to page 116 – Section 8 – AS 1684.2 8.3.4 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.

Projected area of elevation (m2) 8.3.4 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

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

Projected area of elevation 8.3.4 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

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

Refer to page 140 – Section 8 – AS 1684.2 8.3.6.2  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.

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

Wind Direction 1 Calculate all single sided (Gyprock lined) walls for Nominal Bracing 2 x (7.570 – 0.480) + (2 x 1.100) = 16.380m 16.380 x 0.45kN/m = 7.4kN Now Calculate double or Two Sided (Gyprock Lined) Walls

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) = 16.900m 16.900 x 0.75kN/m = 12.7kN

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 7.371 + 12.675 = 20.046 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.

8.3.6.6 Location and distribution of bracing Refer to page 148 – Section 8 – AS 1684.2 8.3.6.6 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

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, 8.3.6.6 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.

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

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

8.3.6.6 Location and distribution of bracing Refer to page 148 – Section 8 – AS 1684.2 8.3.6.6 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

Calculate spacing of Bracing for Wind Direction 2 Refer page 150 of 1684.2 (2006) Wind Speed Ceiling Width Roof Pitch Spacing of Bracing Calculate spacing of Bracing for Wind Direction 2

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

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

Repeat for Wind Direction 2

Calculate the area of elevation for Wind Direction 2 3 785 7 570 2 100 1 350 7 570 x 1 350 = 10 220 m2 3 785 x 2 100 = 7 949 m2 Total Area 18.1m2

Wind Direction 2 Wind Speed Roof Pitch Building Width Pressure / kPa Refer page 122 of 1684.2 (2006) Wind Direction 2 Wind Speed Roof Pitch Building Width Pressure / kPa 1.2kPa

Projected area of elevation 8.3.4 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

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

Refer to window schedule for window sizes Wind Direction 2 Calculate all single sided (Gyprock lined) walls for Nominal Bracing 2 x (14.640 – 0.480) = 28.320m 28.320 – openings = nominal S/S length Refer to window schedule for window sizes

Total length of opening widths = 16.150 Window Schedule: Window W x H W9 Bedroom 1 1.800 1.550 W1 Bedroom 2 1.200 1.550 W8 Bedroom 3 1.200 1.550 W2 Bath & WC 1.800 0.900 W3 Laundry 1.350 0.900 W4 Kitchen 1.650 0.900 W5 Dining 1.200 1.550 W6 Living 1.850 1.650 W7 Family 1.850 1.650 D2 Entry 1.350 2.060 D1 Kitchen 0.900 2.060 Total length of opening widths = 16.150

Wind Direction 2 28.320 – openings = nominal S/S length 12.170 x 0.45kN/m = 5.477kN Now Calculate double or Two Sided (Gyprock Lined) Walls

Wind Direction 2 Two Sided walls for Nominal Bracing (11.510 + 4.300) – 5 doors @ 0.900 = 15.810 – 4.500 = 11.310m 11.310 x 0.75kN/m = 8.483kN

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 5.477 + 8.483 = 13.960 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 = 10.85 kN

8.3.6.6 Location and distribution of bracing Refer to page 148 – Section 8 – AS 1684.2 8.3.6.6 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

Calculate spacing of Bracing for Wind Direction 2 Refer page 150 of 1684.2 (2006) Wind Speed Ceiling Width Roof Pitch Spacing of Bracing Calculate spacing of Bracing for Wind Direction 2

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 8.3.6.6 & 8.3.6.7, 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.

Wind Direction 2 Bracing for Wind Direction 2 complete.

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 to8.3.6.5 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) + 7.2 = 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.

Wind Direction 2 Bracing for Wind Direction 2 complete.

Exercise 1 Completed