SPECIFICATION FOR THE DESIGN OF - Transcon Steel

72 Commentary on the Prescriptive Method for One and Two Family Dwellings - 2004
Hold Downs Required at Shear Wall Ends
Single Shear Wall: T u = 3,730 lbs T ASD = 2,710 lb
Aligning Shear Walls: T u = 6,910 lbs T ASD = 4,940 lb
Using Simpson’s S/HTT-14 Hold Down with 5/8” diameter bolt for single shear wall:
T allow = 5,260 lbs
T allow = 3,950 lbs (without 1/3 increase for wind/seismic)
T allow > T ASD = 2,710 lb
Using Simpson’s S/HD8 Hold Down with 5/8” diameter bolt for aligning shear wall:
T allow = 7,920 lbs
T allow = 5,940 lbs (without 1/3 increase for wind/seismic)
T allow > T ASD = 4,940 lb
E11.5 Required Sheathing (End Walls)
End wall shear walls use 7/16” OSB fastened with No. 8 screws at 6” at panel edges and
12” at intermediate supports. Per previous calculations, L Required at 2 nd floor = 12.6’; and
L Required at 1 st floor = 17.45’.
Try Type II walls (perforated shear wall):
Determine percentage of fully sheathed wall @ 2 nd floor = (5+12+5)/30 = 0.73 = 73.3%
@ 1 st floor = (5+8+8)/30 = 0.70 = 70%
Maximum unrestrained opening at 1 st and 2 nd floor = 7’, with wall fully sheathed above
and below.
Interpolate for length adjustment factor for both “percent fully sheathed wall” and
“Maximum unrestrained opening”:
At 2 nd Floor:
% Fully Sheathed 6.75’ 7’ 7.5’
60 1.28 1.32
73.3 1.176 1.182 1.203
80 1.12 1.14
Therefore, the required length of fully sheathed (Type II) wall = (1.182)(12.60’) = 14.89’
14.89’ < 22’ ok
At 1 st Floor:
% Fully Sheathed 6.75’ 7’ 7.5’
60 1.28 1.293 1.32
70 1.2 1.21 1.23
80 1.12 1.127 1.14
Therefore, the required length of fully sheathed (Type II) wall = (1.21)(17.45’) = 21.11’