Slide 24 of 45
Notes:
- Connections at sole plates
- We have put shear force into the shear wall through the top plate
- Now we are going to take it out of the shear wall through the sole plate.
- Important: What is the difference between a sill plate and a sole plate?
- Sill plate: Bottom plate on concrete or masonry
- Sole plate: Bottom plate is sitting on wood
- The sole plate connection:
- Is an inherently weak connection – it is difficult to make it strong
- One reason for weakness is that nails must go through flooring, subfloor etc., so penetration of nail is not as good as needed.
- When nails or lag screws resist shear, they must be sufficiently long enough to penetrate through the sole plate and floor sheathing into the framing member below.
- Table 23-G of the UBC specifies the required penetration of nails into the framing member.
- When the nail penetration falls below Table 23-G values, the allowable load for the nail is reduced proportionally up to 50% of its value
- When nail penetration falls below 6 nail shank diameters, the allowable load value is zero
- For this reason, nails often cannot transfer shear forces through thick sheathing.
- What can be done to address this problem?
- If the wall framing is exposed above the floor, as in new framing that has not yet had plaster or drywall attached, the nails can be installed from above.
- However, in some retrofit situations, the wall framing above is not (or cannot be) exposed.
- In this case, it may be possible to add framing clips where the underside of the floor and the rim joist or blocking meets.
- Short joist hanger nails should be used to attach the clips to the joist or blocking.
- Longer nails or wood screws should be used to penetrate up through the floor decking and into the sole plate above.
