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Re: Transfer force of large tie beam

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Jordan,

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.
> Rich            ******* ****** ******* ******** ******* ******* *******
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