Slide 37 of 45
- Use Plate Washers
- Square plate washers should be used instead of round washer. 1997 building code will require this.
- Testing shows that these function better than round washers in earthquakes
- Round malleable washers tend to fold up and split the sill plate during an earthquake, especially when the sill plate hole is oversized.
- During the 1994 Northridge earthquake, sill plates often split or pulled through anchor bolts.
- The square plate washer is more effective in creating a good friction connection between the sill plate and the bolt. It also makes tightening of expansion anchors easier.
- The figure shows a square plate washer used with an adhesive anchor. Note that the adhesive has spilled out of the hole. This is correct, as we will discuss shortly.