Thanks for the response.
I looked at my numbers a little more closely this morning and realize my
maximum load combination is 88.9 kips horizontal thrust. The 60 kips was
from the roof snow load. I also have drifted snow load on the worst case
frame, plus the dead load.
I wasn't thinking of using 40 grade steel reinforcing. I was considering
using A36 rods. It would be too confusing to try to get 40 grade rebar
for the project. If I limit the stress to 22 ksi I need (4) 1.125 dia
rods. I'm still wondering about an efficient way to get the force out of
the anchor bolts and into the rods. I 'm considering using some angles to
'dead head' the rods in the pier. I can see I would put a significant
cage of rebar around the bolts. I would detail a concrete tie beam below
the floor slab. I'm still not comfortable with how the force load path
travels from the bolts to the tie rods.
Rich
> Last I heard, grade 40 was a fractional cent per pound less than
> grade 60, so I'm not sure theres much economy there. 60 kips is
> only, what, about 4 number 6 bars for strength? I haven't done a
> PEMB with forces this large recently, so I can't give any
> specifics on details. If it were me, I would just check every
> material interface from the baseplate down to make sure there were
> no weak spots.
> Jordan
>
> Rich Lewis wrote: I have a pre-engineered metal
> building with some large tie beam forces. They are around 60 kips. The
> reason they are so high is a 40 psf roof snow load with a 13 feet eave
> height. The clear span of the rigid frame is 80 feet. For smaller loads
> I typically wrap the anchor bolts with a ‘U’ shaped rebar and
> use mechanical ties for the rebar of the tie beam. With loads this high
> I was wondering if I should be using a better mechanism for transferring
> the forces. What other options might I consider to transfer the thrust
> force from the rigid frame to the tie beam? I’m also wondering
> about stretching the tie bar itself. This is a metal frame with metal
> siding. What kind of limit should I use as a maximum stretch of the
> bars? Should I consider using lower strength steel and a larger area in
> order to reduce the delta from the PL/AE stretch? Thanks.
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