Bolt Design for Ledger Beam 3

[cap4000]

I have a 3 x 12 bolted to masonry wall for floor framing. Can someone verify the single shear value of a 7/8 bolt. Any tips will greatly appreciated. I have a value of 495 pounds but it seems low. Thanks

 

[AELLC]

What is the species and grade of the ledger?

 

[cap4000]

It will be Doug Fir Large Grade 2 or better

 

[MiketheEngineer]

Masonry wall might be controlling?? But 500 lbs actaully doesn't seem unreasonable - but haven't checked.

 

[AELLC]

I get 1010 pounds for the ledger itself, but don't have the latest values for masonry.

 

[cap4000]

I think the block reduces the value around 50% but not sure.

 

[AELLC]

No, it doesn't work that way. Problem is, I don't have the latest masonry code. The 1010 pounds is the minimum value of all possible failure modes of the bolt in the wood ledger by itself.

There is a separate check for failure mode in the masonry. If the masonry is uninspected, the allowable stress is reduced by half but that is not applied to the 1010 pounds wood value...it is applied to the bolt value in masonry.

Is this regular solid-grouted CMU at least 8" wide? Also, the bolt needs to be 6" into masonry.

 

[DST148]

@Cap4000 : Ref: ACI 530-05, Section 2.1.4.2.3 - Allowable Stress Design of masonry
The allowable load in shear primarily depends on the strength of masonry, edge distance of anchor from
top of the masonry, and area of anchor.
Assuming min. strength of masonry as 1500 psi and fy for steel as 36000 psi, I get the following values:

edge dist. from top of masonry ----- Allowable load in shear
10.5" ---------------------------------------------- 1917 lbs.
8" -------------------------------------------------- 1412 lbs
6" -------------------------------------------------- 1009 lbs
4" --------------------------------------------------- 605 lbs
3" -------------------------------------------------- 403 lbs

The minimum effective embedment length of the headed and bent-bar anchor bolt shall be 4 bolt diameters, but not less than 2".

 

[MiketheEngineer]

Most large anchor suppliers, Hilti, Simpson, Fastenal, etc can supply you tables that fit these exact requirements.

 

[spats]

The American Wood Council has an online calculator.

http://www.awc.org/calculators/connections/ccstyle.asp

I think it's appropriate to use concrete as your main member type, although I don't what their assumption is for dowel bearing strength in the masonry. The only reference I've ever found is the 1997 NDS, Table 8.2E, which gave a dowel bearing strength of 6000 psi for >= 2000 psi concrete or for masonry. It probably doesn't matter, as Mode IIIs will likely control.