High Capacity Shear Walls

The American Plywood Association performed a series of experiments to test the limits of shear wall strength. Their findings can be found in APA Research Report 138.

138 Word

Looking at this table we are using:

(1) Structural 1 Plywood

(2) Plywood that is 23/32 ” thick.

(3) The stud framing that is 4″ wide.

(4) The rows of nails.  For example, 3 lines of fasteners means there are 3 rows of nails going up and down on the studs.

APA Research Report 138 :  describes tests prove show very high strength shear walls can be produced by using multiple rows of nails or staples in wood framing that is wider than the normal 1-1/2 inch wide framing used in new construction.  These high capacity shear walls also need high capacity foundations.  As you can see a shear wall built in this way can resist 1900 pounds of earthquake force and represents the strongest shear wall ever tested.  Even though it has never been tested, a two sided shear wall of this type could have an enormous ability to resist earthquakes.

Overturning Forces in High Capacity Shear Walls

A typical application would be typical building in San Francisco where much of the front lower story is taken up by a garage and the rest is taken up by a stair wall.  In these circumstances the front of the building is not connected to any foundation.  This is also a preferred method in terms of effectiveness and often cost compared to moment columns. 

The next consideration is uplift or overturning forces.  High capacity shear walls must resist a tremendous amount of overturning.  For example, if the shear wall can is resist 1900 pounds per linear foot of lateral earthquake force, it will also need to resist #15,200 pounds of overturning force.    For this reason proper sizing of hold downs is critical.  In this table from Simpson Strong-Tie, the name of the hold down appears under Model No.

Hold Downs

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