Shear Wall Design

Comparison of SSW and PSW Design Methods
 
          Two shear wall design methodologies have been presented in this tutorial.  Both methods have advantages and disadvantages.

           The segmented shear wall (SSW) approach is the "tried and true" method.  It relies only on the segments of full-height sheathing to resist shear, and neglects the effects of sheathing above and below openings.  In general it yields a higher design shear capacity than the perforated shear wall (PSW) method.  However, the SSW method also requires hold-downs at the bottom corners of each full-height shear wall segment to resist overturning.  This may result in a large number of hold-downs which are labor-intensive to install and add cost to a project.

            The perforated shear wall (PSW) design approach is the newer method, having been developed in the early 1980's by Professor Hieto Sugiyama in Japan (Sugiyama 1981).  The PSW method takes into consideration the contribution to shear resistance of the sheathing located above and below openings, and reduces the required number of hold-downs.  However, the PSW method typically results in lower shear capacity for a given wall.  This is oftentimes acceptable since shear walls designed using the traditional SSW method frequently have excess shear capacity.  The following chart illustrates a comparison between allowable shear capacities for the SSW method versus the PSW method.
 

          This chart presents the calculated shear capacities for 8 ft by 8 ft walls with a 30.5 in. wide window that varies in height from 24 in. to a full wall height of 96 in.  It is important to note that regardless of the opening height, the SSW method gives the same capacity (2025 lb), whereas the PSW method provides decreased capacity as the amount of sheathing above/below the window decreases.


Topics of this module include:

IntroductionLoad Path, Segmented Design Method, UBC Design Table, Wall Shear, Dimension Ratios,
  Chord Design,  Anchorage, Deflection, Perforated Design MethodShearwall Failures

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