Bolts/Beam supporting floor joists...
Bolts/Beam supporting floor joists...
(OP)
A homeowner wants to install an addition on the side of his house and he said he would like to bolt a double 2x10 beam to his existing stone foundation. The new floor joists will either sit on top of the beam or on joist hangers fastened on the beam.
According to my calcs the load on the beam will be 263 plf which equates to 100,000 lb-in (16' span). A double 2x10 beam can only support 41,200 lb-in. so the beam will obviously not work. A 2-ply lvl (11-7/8" deep and 16'6" long) can support 422 plf so this could be used.
My question is how do the bolts affect things? The bolts are securing the beam to the existing structure so do they need to be desinged to carry the 263 plf or is the beam still the controlling factor?
If my question is not clear let me know. Thanks.
According to my calcs the load on the beam will be 263 plf which equates to 100,000 lb-in (16' span). A double 2x10 beam can only support 41,200 lb-in. so the beam will obviously not work. A 2-ply lvl (11-7/8" deep and 16'6" long) can support 422 plf so this could be used.
My question is how do the bolts affect things? The bolts are securing the beam to the existing structure so do they need to be desinged to carry the 263 plf or is the beam still the controlling factor?
If my question is not clear let me know. Thanks.






RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
Bolting into a stone foundation is another story. You might consider through bolting with a backer plate and nut inside the wall.
RE: Bolts/Beam supporting floor joists...
Bolting a 2-ply ledger to old stone might be difficult and there is built-in eccentricity so you'll have pull-out on the anchor bolts, not just shear.
I see absolutely no reason to use a two-ply ledger as the span is MiketheEngineer said, between bolts.
Two plies just adds to the eccentricity.
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
The problem here will be in the details....
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
BA
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
According to my tables, one 1/2" bolt can carry a factored load of 2.52 kN or 567# perpendicular to the grain in a 38mm thick SPF ledger with bolt embedded 100 mm into the concrete. So the spacing of a 1/2" bolt would be 567/395 = 1.4' or about 16" for a concrete foundation wall (not sure about stone wall).
BA
RE: Bolts/Beam supporting floor joists...
RE: Bolts/Beam supporting floor joists...
If you are in the US you would use the American Forest & Paper Association (AF&PA) National Design Specifications for Wood Construction (NDS). You go to Table 11E and select the wood specie, side member thickness, bolt diameter and find the Z perpendicular value.
You didn't mention what the load is from but you can modify the allowable capacity by the Duration of Load factor. If it was from snow the Cd would be 1.15 times the loads in the Table.
I hope that this helps.
RE: Bolts/Beam supporting floor joists...
The table I used is "Bolt Selection Tables - Single Shear, Wood to Concrete" page 262 of Wood Design Manual 2001 published by the Canadian Wood Council. In USA you would have a different reference.
The factored load should be 1.25*DL + 1.5*LL in Canada. Since I didn't know the dead load, I conservatively used 1.5*263 = 395#/' for factored load.
BA
RE: Bolts/Beam supporting floor joists...
Just so we don't confuse things, I was using ASD (Allowable Stress design) and BAretired was using LRFD (Load & Resistance Factor Design).
I don't use LRFD for wood and I don't think that there is a duration of load factor (Cd) in LRFD.
I hope that I didn't muddy up the water.
RE: Bolts/Beam supporting floor joists...
Is there a place I can get a copy of the NDS book or are the tables online anywhere? I know I can get the NDS book at awc.org but is there someplace cheaper?
Thanks.