Shear Wall Design

Dimension Ratios
 
          The International Building Code (IBC) and the Uniform Building Code (UBC) place limits on the dimensions of wood-frame shear walls.  These restrictions are based on the poor performance of tall, narrow wood-frame shear wall segments observed in previous earthquakes. The limits are in the form of maximum height-to-width ratios (h:b).   The maximum allowable ratios are a function of the type of shear wall construction and the location (seismic zone) of the structure.  Much of the information in UBC Table 23-II-G is presented below.

 Be sure to pay special attention to the footnotes as they may dictate your design.

Material

Horizontal Diaphragms
maximum. Span :Width 

Shear Walls
maximum Height :Width

1.  Diagonal Sheathing, conventional 3:1 1:11
2.  Diagonal Sheathing, special 4:1 2:12
3.  Wood Structural panels... nailed all edges 4:1 2:12,3
4.  Wood Structural panels... no blocking 4:1 not permitted

1 .In Seismic Zones 0, 1, 2, 3, the maximum ratio may be 2:1
2  In Seismic Zones 0, 1, 2, 3, the maximum ratio may be 3½:1
3  In Seismic Zones 4, the maximum ratio may be 3½:1 for walls not exceeding 10 feet in height on one side of the door to a one-story
    Group U Occupancy

 

Topics of this module include:

IntroductionLoad Path, Segmented Design Method, UBC Design Table,
Wall ShearChord DesignAnchorage, Deflection,
Perforated Design Method, Method Comparison, Shear Wall Failures