Shear Walls With Openings - The Analysis of Irregular Shaped Structures - page 374

where L tot = total length of perforated shear wall including lengths of perforated shear
wall segments and lengths of segments containing openings

A o = total area of openings in perforated shear wall where individual opening
areas are calculated as opening width times clear opening height. Where
sheathing is not applied to the framing above or below the opening, these
areas shall be included in the total area of the openings

h = height of perforated shear wall

Σ L i = sumofperforatedshear wall segmentlengths t ,

Figure 10.2 shows a typical perforated shear wall elevation. Hold-downs are only
installed at each end of the wall in accordance with SDPWS Section 4.3.6.4.2. Addition-
ally, in accordance with SDPWS Section 4.3.6.4.2.1, the bottom plates at the full-height
sections of the wall are required to be anchored for a uniform uplift force. The resistance
of a perforated shear wall shall be calculated as follows:

Method

1. Determine the percent of full-height segments = Σ LL

i / tot .

2. Determine the maximum opening height. Where areas above and below the
opening are unsheathed, the opening height shall be equal to the full height of
the wall.

3. The shear resistance adjustment factor C o is determined from SDPWS
Table 4.3.3.5. Interpolation is allowed.

4. The unadjusted allowable nominal shear capacity v allow is taken from SDPWS
Table 4.3A and is to be adjusted for the aspect ratio as required. The maximum
aspect ratio h / w of individual wall piers shall not exceed 2 : 1 for seismic or
3.5 : 1 for wind. Where any segment exceeds 2 : 1 for seismic but does not exceed
3.5 : 1, the unadjusted shear resistance shall be multiplied by 2 w / h .

5. Adjusted shear resistance = C o v allow .

6. V wall = C o V allow Σ L i maximum shear capacity of wall.

It can be seen that the difference between the Sugiyama method and the SDPWS
method is that the shear capacity of the wall for the Sugiyama method is determined by
multiplying the reduced shear value by the full length of the wall; in contrast, the
SDPWS method multiplies the reduced shear factor by the sum of the lengths of the
full-height sections. Comparing the two methods will show that the SDPWS method is
only slightly more conservative.

Limitations of SDPWS Section 4.3.5.3

1. Full-height segments must be located at each end of the perforated shear wall.
Openings shall be permitted to occur beyond the ends of the perforated shear
wall, provided the lengths of such openings are not included in the length of
the perforated shear wall. Where full-height segments do not meet the aspect
ratio requirements, the segment cannot be used.

2. The aspect ratio limitations of Section 4.3.4.1 and Fig. 10.3 a shall apply.