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SDPWS 4.3.2.3. defines a "perforated wall" as an entity with full height segments at the ends and one or more openings within, and other full-height segments between the openings. Non-shear-resisting narrow segments can also exist within the wall.
These walls require hold-downs at the wall ends only, but SDPWS 4.3.5.6 reduces the shear capacity by a perforation factor Co (opening coefficient) based on opening size, and increases the design hold-down forces , drag strut forces and deflection force by the inverse of that factor.
These walls appear with diagonal hatching in Plan View. They are distinguished in Elevation view by showing the perforation factor.
As per SDPWS 4.3.3.4, aspect ratio limitations apply to each full-height sheathing segment within the wall, such that narrower segments are not included in the length of the perforated wall. Segments within the next range of aspect ratios are penalized by reducing the effective length of the segments, thus increasing the unit shear force, rather than by a shear capacity reduction. The narrow wall wall penalty is also applied in various ways to hold-down forces, drag strut forces and deflection force.
Openings and narrow segments are neglected when determining the effective length of the wall for shear force distribution, so in the absence of permissible narrow segments with an effective length reduction, the average shear force on all segments is the same as a segmented wall of the same proportions. In contrast to segmented walls, the shear force on each segment of the perforated wall is the same as all the others regardless of their relative stiffness, and the wall is analyzed as a unit.
Any non-full-height segment that occurs at the end of wall designated as Perforated in Shearwalls, and the opening next to it, is ignored when deciding where to place hold-downs and when calculating the perforation factor. Thus perforated walls are automatically pared down to their extent between the extreme full height sheathing segments when used in force distribution, design and deflection routines.
Other restrictions apply to perforated walls that are implemented in Shearwalls:
Refer also to Perforated Shear Wall Design the following for more details.