Anchor bolt embedment

[mont1230]

The 1995 CABO code was the last to have anchor bolts 15" embedment into masonry and the 1998 ICC came out with 7" embedment into masonry. Does anyone have a commentary or explanation why this occurred?

 

[steveray]

Not me....Why do you ask? Maybe something in ACI 318? I do not recall ever seeing anchor bolts that long for a house.

 

[mont1230]

We have amended this since I came on in 2006 and was trying to justify to our code committee to keep the 7" embedment, instead of 15" embedment like it once was.

 

[mtlogcabin]

Steel construction

Table R505.3.1(1)

a. Anchor bolts are to be located not more than 12 inches from corners or the termination of bottom tracks (e.g., at door openings or corners). Bolts extend a minimum of 15 inches into masonry or 7 inches into concrete. Anchor bolts connecting cold-formed steel framing to the foundation structure are to be installed so that the distance from the center of the bolt hole to the edge of the connected member is not less than one and one-half bolt diameters.

 

[zigmark]

Below in item #5 is the 95 CABO requirement;

"FIGURE 403.1a CONCRETE AND MASONRY FOUNDATION DETAILS

NOTES:

1 Exterior footings shall extend to below the frost line unless otherwise protected against frost heave. In no case shall exterior footings be less than 12 inches below grade.

2 Footing widths (W) shall be based on the load-bearing value of the soil in accordance with Table 401.4.1 or shall be designed in accordance with accepted engineering practice.

3 Spread footings shall be a minimum of 6 inches thick, and footing projections (P) shall be a minimum 2 inches and shall not exceed the footing thickness.

4 Footings shall be supported on undisturbed natural soil or engineered fill.

5 The sill plate or floor system shall be anchored to the foundation with ½-inch-diameter bolts placed 6 feet on center and not more than 12 inches from corners. Bolts shall extend a minimum of 15 inches into masonry or 7 inches into concrete. Sill plates shall be protected against decay where required by Section 322.

6 Pier and column footing sizes shall be based on the tributary load and allowable soil pressure in accordance with Table 502.3.3b."

ZIG

 

[Sifu]

Interestingly there is an illustration in the 09 IRC that shows a bolt extending down into the second course of masonry but no mention of that so my guess is that it is a holdover illustration that didn't get edited out. I did see a house once that was destroyed in a storm, I think it was a flood. The only thing left was the foundation, without the top corse of CMU, the floor was moved off the foundation with the 1st course still attached to it by the anchor bolts.

 

[mont1230]

I what to see if anyone knows why it went from 15" embedment to 7" embedment in masonry?

 

[linnrg]

I think because most are installing grout in all cells versus the older practice of grouting only the cells with reinforcement

 

[Msradell]

I think because most are installing grout in all cells versus the older practice of grouting only the cells with reinforcement

Is that really being done in most areas? Haven't lived in an area where they do CMU foundation walls recently, everything around here is poured. When I did live in an area with CMU for the walls only the cells was reinforcing were grouted.

 

[linnrg]

I think it was in early versions of IRC for fully grouted in seismic zones, Do not find the same in newer IRC version all of which have been fully revised. We have been requiring the full grout for them, but do not see residential foundations made of masonry like we used to. Our most common is slab on on grade shall frost protected with in floor heat, or ICF foundations and crawl spaces.

on commercial projects we still see masonry foundations and walls fairly regularly and they are all specified by structural to be solid filled