There are many factors that affect the stability of the wall. I’ll assume all those issues are correct: 1) grade of cmu, 2) grade of mortar, 3) grade and placement of grout, 4) grade and placement of masonry reinforcement, 5) adequate design and correct placement (edge distance) of reinforcement for seismic activity for your area, (and you have high stresses in your area), 6) correct corrosion protection for your area, (and you have high corrosion in your area), 7) lateral stability, (including adequate soil resistance in your area).
Instead, I’ll concentrate on the single issue of supporting a 6’ high fence from rotating and causing the anchors to fail.
Assuming the fence posts are about 6’ on center and the fence is 6’ high and wind resistance is about 30 psf in your area, the load is 1,080 ft.-lbs. Rotation is taken 3’ from the base for a load of 3240 ft.-lbs. Assuming there are two anchors resisting this force, so each anchor will need to resist about 1620 ft.-lbs. Those anchors you’re suggesting to use are inadequate.
The Code (see ICC Section 2109.7) outlines steel connection requirements. The only anchors that will provide adequate withdrawal resistance are wedge anchors or anchor bolts with a 2” hook. Wedge anchors will provide about 3000 lbs. pullout strength (which has a safety factor of about 2 with adequate edge distance). See
Using a 1/2” wedge anchor, you’ll need about 2 1/2” edge distance. This is impossible with your 4” steel plate and about 1 1/4” side shell on the cmu. The Code requires an edge distance based on the size of the bolt:
- 1/4” = 1 1/2”
- 1/2” = 2 1/2”
- 5/8” = 3”
This is based on standard grade concrete, (i.e.: 2500, 3000, etc.) If you’d use a “high-strength” concrete it can be reduced. (See ICC Chapter 19, Table 1908.2)
Perhaps the reason the previous owner never installed the fence is because they knew it would not be adequate.