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Re: Plywood shear wall definition

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Plywood shear wall definition
• From: "Dennis S. Wish, PE" <dennis.wish(--nospam--at)verizon.net>
• Date: Thu, 27 Jan 2005 19:32:57 -0800

```Bill,
```
You are correct, unless the discontinuity occurs mid height in which case the sheathing on each side can help to control out-of-plane forces (i.e. wind) and additional straps can be used to resist bending around this joint. The use of holddowns would be necessary if the upper panels are narrow (example: openings occur in the 4-inch pony wall that calculates into uplift or overturning on the panel). In either case, is holddowns are not used, then coiled straps may be sufficient depending on the rated uplift and the same coiled strap or LST (MST etc) can be used on both sides to address out-of-plain (forces normal) buckling. I'm not sure if I make this any clearer or simply muddied the water. The simple point is to protect the load path against failure at any discontinuity (break) that may occur in-plane and out-of-plane.
```Dennis

BCainse(--nospam--at)aol.com wrote:

```
A little clarification: the definition of the aspect ratio, per CBC Figure 23-II-, "General Definition of Shear Wall Height to Width Ratio," is based on the ratio of the clear height (measured between the _bottom_ of the framing for the upper diaphragm and the lower diaphragm) to the width of the sheathing unless shear transfer is provided around openings. See the cited figure for the latter case. Regards,
```Bill Cain, SE
Berkeley CA
```
In a message dated 1/26/2005 12:07:55 PM Pacific Standard Time, Jnapd(--nospam--at)aol.com writes:
```
Mark:
```
1. There is no problem switching plywood from outside to inside
```    face of studs if all other requirements are completed as you stated.
```
2. If the holdown strap is on the outside face there should be
```    no problem.  Do not put on inside face.  If PHD holdown is used
make sure they lineup. A little offset on the upper more to the
```
center of the lower post. I am assuming the studs change at the 2nd floor
```    diaphragm.  The aspect ratio is between diaphragms, (ground to 2nd
floor and 2nd floor to roof) not between ground and roof.
```
Are these thoughts to be used in a possible plaintiff or defendant
```    position.
```
Joe Venuti
```    Johnson & Nielsen Associates
Palm Springs, CA

```
```

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