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The program implements the provisions in O86 11.5.4 for shear wall resistance and 11.7.1.3 for deflection for unblocked wood structural panel (WSP) sheathing.
Blocking
You can specify that only one side of a wall is blocked; that is, the sheathing is nailed to the blocking on that side, but not on the other. All shear wall materials can be designated as unblocked or blocked.
Unblocked wood structural panels (plywood and OSB) are modified by the Jus factor as described below. Gypsum wallboard lateral design strengths vd depend on whether the wall is blocked or unblocked. .
Unblocked is unavailable for walls greater than 4.88 m (16.0') in height to comply with O86 11.5.4. A wall changed to that height will cause an unblocked wall to change to be blocked.
Jus Factor
The program determines Jus factors from Table 11.3 based on the based on stud spacing and intermediate nail spacing on that each side ot the wall, as shown below. ( 19.2 is the Shearwalls stud spacing choice corresponding to 500 mm, representing 5 intervals on an 8' sheet of plywood).
Intermediate Nail Spacing |
Stud Spacing |
|||
300 mm (12") |
400mm (16") |
500 mm (19.2") |
600 mm" |
|
150 mm ( 6" ) |
1.0 |
0.8 |
0.6 |
0.5 |
300 mm ( 12" ) |
0.8 |
0.6 |
0.5 |
0.4 |
For values of intermediate nail spacing between 150 mm and 300 mm , the factor for 300 mm spacing is used, in other words, the program does not interpolate Table 11.3.
Shear Resistance for Unblocked Walls
As per 11.5.4, Shearwalls applies the Jus factor to the shear resistance of WSP sheathing with 150 mm (6") edge nail spacing, regardless of the actual nail spacing, to arrive at the design capacity.
Unblocked GWB shear walls have lower shear strengths vd in Table 11.4. These strengths are based on 400 mm (16") stud spacing, and are further reduced for greater stud spacing.
Deflection of Unblocked Walls
As per 11.7.1.3 the deflection of an unblocked WSP wall with 150 mm (6") edge nail spacing is calculated regardless of the actual nail spacing, and divided by the Jus factor to determine the deflection of the segment.
There is no modification to the deflection of unblocked GWB walls.
Output
The Sheathing Materials table indicates whether each side of the wall is blocked and shows the Jus factor for that wall construction.
Shear Design Table
The shear resistance shown in the table for an unblocked segment incorporates the Jub factor,
Deflection Table
The deflection shown in the table for an unblocked wall segment incorporates the Jub factor,