Tabulated Design Capacities

1. Shear Capacities

   The following changes to unit shear capacity values from Tables 4.3A-D were implemented.

   1. Seismic Capacities
      1. Gypsum-based Materials

         Seismic capacities for gypsum-based materials in Table 4.3C decreased by a factor of 1.4 due to the application of the new seismic ASD factor of 2.8 from 4.1.4 rather then the previous 2.0, without a corresponding change to the tabulated shear capacities.

      2. Other Materials

         For other materials, the tabulated seismic capacities increased to compensate for the increase of the ASD factor to 2.8 factor, which therefore had no effect other than due to rounding. Factored seismic values previously rounded to the closest 5 plf are can now be slightly different, for example 390 lbs is now 389.3 and appears in the output as 389. In all cases the difference is less than 1 plf.

   2. Wind Capacities

      For wind design, the previous implementation multiplied the tabulated seismic values by 1.4 then divided by 2, which created slight inaccuracies, such as 476 plf instead of 475 plf . These inaccuracies have been eliminated and wind design values are now exactly the tabulated values divided by 2. In all cases the change is less than 1 plf.

   3. Reduction Factor for 10d Nails

      A new Note 10 to Table 4.3A applying a 0.92 factor to wood structural panels using 10d nails has been implemented, and if applicable, a note appears under the Sheathing Materials table giving the reduction.

2. Perforated Wall Capacity
   1. Shear Capacity Adjustment Factor Co

      A new formulation of perforated wall factor C_o in 4.3.5.6 and Equation 4.3-5 was implemented. This equation replaces the choice of using a different equation and tabulated values in previous editions of the SDPWS.

      1. Design Setting for Co Calculation

         The Design Setting offering you a choice of using SDPWS 2015 Eqn. 4.3-5 or Table 4.3.3.5 has been removed.

   2. Shear Capacity Calculation and Aspect Ratio Factor

      New definition of perforated shear wall capacity in Eqn' 4.3-5 that effectively introduces an aspect ratio factor = Sbi / Sb where bi are the full-height sheathing segment lengths adjusting for for narrow segments as per 4.3.3.4 and Sb is the sum of the unadjusted lengths. The value Sbi used to be incorporated in the Co factor.

      1. Output

         This factor is now shown in the Shear Results table for perforated walls in the same column as the Aspect Ratio factor for for Segmented and FTAO walls, with an explanation in the table legend.

   3. Capacity Limit

      There is no longer a separate capacity limitation on single-sided perforated shear walls; the double-sided limitation in 4.3.3.2(4) now applies to single- and double-sided walls.

3. Out-of-Plane Wind Load Sheathing Capacities

   The following changes to Table 3.21A for out-of plane wind loads used for component and cladding design of sheathing bending and shear strength were implemented.

   1. OSB vs. Plywood

      Allowable loads are now provided separately for OSB and plywood. Previously the lower of the OSB and plywood values was used.

   2. Structural 1 vs Structural Sheathing

      For plywood panels applied parallel to the studs (i.e. vertically), there are separate values for Structural 1 and Structural Sheathing.Previously, the lower Structural Sheathing values were used for both.