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For each material type, the table below lists the maximum allowable aspect ratio h/bs, where , bs = segment length and h = height of segmented or perforated wall segment or force-transfer pier.
For blocked wood structural panels and fiberboard, values are given for adjusted and unadjusted shear capacity, and within that range of aspect ratios the given Shear Capacity Adjustment must be applied to the shear capacity for segmented and force-transfer walls, and to the effective total segment length for perforated walls. Factors are different according to whether you have selected capacity-based or deflection based force distribution methods in the Design Settings.
Wall segments that have aspect ratios that are are greater than the maximum are treated as non-shearwalls and do not attract shear force. Force transfer piers greater than the maximum are rejected when you make a user interface change that would create one.
The areas of the program where you can see these aspect ratios and factors are given below the table.
Aspect Ratio Limits and Factors |
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Shearwalls |
SDPWS |
Wood Structural Panels |
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Maximum aspect ratio |
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SDPWS 4.3.4, Table 4.3.4 |
Blocked, unadjusted |
3.5:1 |
3.5:1 |
Blocked, unadjusted |
2:1 |
2:1 |
Unblocked |
2:1 |
2:1 |
Shear Capacity Adjustment* |
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4.3.4.2, 4.3.3.4.1 Exception 1. |
Capacity-based force distribution |
2b,/ h |
2b, / h |
Deflection-based distribution |
1.25 - 0.125 h / b, |
1.25 - 0.125 h / b, |
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Fiberboard |
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Maximum aspect ratio |
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SDPWS 4.3.4, Table 4.3.4 |
Adjusted |
3.5:1 |
3.5:1 |
Unadjusted |
1:1 |
1:1 |
Shear Capacity Adjustment* |
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4.3.4.2, 4.3.3.4.1 Exception 2 |
Capacity-based force distribution |
0.1 + 0.9 b,/ h |
0.1 + 0.9 b,/ h |
Deflection-based distribution |
1.09 - 0.09 h / b, |
1.09 - 0.09 h / b, |
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*Applies to segmented and force-transfer walls only; for perforated walls the lengths of the wall segments are factored by 2b,/ h in the calculation of Co . This has the effect of decreasing Co . which is applied to the shear capacity. |
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Lumber sheathing |
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Maximum aspect ratio |
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Table 4.3.4 |
Horizontal, Vertical |
2:1* |
Doesn't say |
Single Diagonal |
2:1 |
2:1 (Refers to Diagonal, conventional) |
Double Diagonal |
3.5:1** |
Doesn't say |
* Use value for single diagonal in absence of guidance for horizontal and vertical lumber |
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** Use value for wood structural panels, on the assumption that "conventional" refers to single diagonal only. |
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Capacity-based force distribution not allowed as per SDWPS 4.3.4.2 |
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Gypsum and plaster |
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Maximum aspect ratio |
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4.3.4, Table 4.3.4, Note 1 |
Unblocked |
1.5:1 |
1.5:1 |
Blocked |
2:1 |
2:1 |
Capacity-based force distribution not allowed as per SDWPS 4.3.4.2, |
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Plan View
The program shows segments as greater than the maximum aspect ratio as hollow, as if they were non-shearwalls. Segments to which an aspect ratio is applied are shown with diagonal hatching.
Elevation View
The aspect ratio and any applicable aspect ratio factors are shown on each wall segment in Elevation view.
Wall and Shear Line Dimensions Output
The Wall and Shear Line Dimensions table of the Design Results output shows the aspect ratio of all segments
Shear Results Output
The program shows the Aspect Ratio factor in the wall segment row the Shear Results table in the wall row in the column Cub/Asp.