Shear Resistance

 

Panel Sheathing

1. wide acceptance
2. economy of installation
3. high allowable unit shears
4. simple

 

 

Lumber Sheathing

in Special Design Provisions for Wind and Seismic (SDPWS) Supplement

 

 

Shear

through the thickness (panel)

nail capacity of the framing  (vs capacity of the nail)

 

 

References

 IBC chapter 23 - Wood

 

SDPWS Supplement

 

 

Nail Patterns

unblocked - two edges not supported by framing minimum 6-in. OC along supported edges minimum 12-in. OC along intermediate framing (field nailing)
blocked can vary spacing, nail size, panel type

direction of continuous panel joint

direction of unblocked edge

 

 

Failure Modes

panel buckling 1, 2

nail deformation

nail pull through  (3/8-in. edge distance)

splitting the framing

• reductions for species other than DF-L and SP
• 2X framing has 10% less capacity than wider
• 3X or wider required for ≤ 3-in. spacing

source 1, 2

 

 

Six Load Cases

compare

1. direction of lateral force
2. direction of continuous panel joint
3. direction of unblocked edge (if it is unblocked)

 

Case Orientation to Load Panel Orientation Framing Continuous Panel Joint Unblocked Edge 1 //  ⊥ ⊥ strong 2 ⊥  ⊥ // strong 3  ⊥ // // strong 4  // // ⊥ strong 5  // both ⊥ strong 6  ⊥ both // strong

SDPWS

IBC

 check both lateral load directions:  transverse, longitudinal

 

If a thicker panel than that given in the table is used, the unit shear from the table should be based on the nailing used.  No increase in shear is permitted because of the increased thickness. If a larger nail size is used for a panel thickness given in the table, the unit shear from the table should be based on the panel thickness.  No increase is permitted because of the increased nail size.

 

tongue-and-groove, panel clips, etc CANNOT substitute diaphragm blocking

 

 

Nail Sizes

penny weight/size, length, diameter

Building Construction Illustrated, 3rd Ed, by FDK Ching and C Adams, Wiley, 2001

nails for nail guns

 

 

Nail Penetration

1-1/4-in. for 6d nails
1-3/8-in. for 8d nails
1-1/2-in. for 10d nails

reductions possible in NDS

wood connections, fastener withdrawal

overdriving nails: link, link (see overdriven nails near bottom)

 

 

Staples

• 3 staples/sec
• 12.7 staples/sec
• 27 staples/sec
• video 1
• video 2  (2:23)

 

• 16 gauge wire
• > 1-in. penetration
• minimum crown width
• staple orientation

 

Bostitch T35 stapler

• 16 gauge
• 1" crown
• 0.5 thru 1.25" length

Senco SNS40 stapler

• 16 gauge
• 7/16" x 2.00"
• 7/16" x 1.75"
• 7/16" x 0.75"
• no oil needed