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Re: Hexagonal Foundation Pedestal for Vessels, Stacks, Etc.

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In almost every instance I've seen lately, the anchor bolts are able to be 
anchored into the concert by embedment alone. You make sure there's enough 
"meat" in the pedestal for the pullout "cone". The bolts are snugged to the 
 foundation to make sure there's always compression between the base plate 
and the concrete surface (grout pad), so the critical limit states are nearly 
 always the bearing at the anchorage (usually a Hex or Heavy Hex bolt head) 
 and tensile capacity of the bolt.

I typically put pretension in the bolts of 50% to 70% Fu, using "squirter" 
DTI washers. The resulting maximum additional tension from wind or EQ 
overturning is not much per bolt then.

There are typically "a lot" of bolts but not always. For instance, the one 
I'm looking at now requires only (8) 1" Dia. Bolts. It's a 12' Dia. X 32' 
vertical vessel, and the ASCE 7-10 wind speed is 140 mph.

William L. Polhemus, Jr. P.E.

5

> On Sep 30, 2014, at 1:52 PM, <Dick_Roberts(--nospam--at)oxy.com> <Dick_Roberts(--nospam--at)oxy.com> 
> wrote: 
> I would think ( I try not too - it hurts my head ) the vertical bars would 
> have to be sized to transfer the tension from the anchor bolts to the
> foundation. Not for compression. A foundation that size must have a lot 
> of anchor bolts.
> 
> Grumpy old man
> 
> -----Original Message-----
> From: seaint-seaosc(--nospam--at)mail-list.com [mailto:seaint-seaosc(--nospam--at)mail-list.com] On
> Behalf Of Bill Polhemus Sent: Tuesday, September 30, 2014 2:10 PM
> To: seaint-seaosc(--nospam--at)mail-list.com
> Subject: [SEAINT-SEAOSC] Hexagonal Foundation Pedestal for Vessels, Stacks, 
> Etc.
> 
> This is something that has bothered me for years now, and I wonder if 
> anyone here, who might have some experience with design of foundations for 
> process equipment, has an opinion.
> 

Truncated 1087 characters in the previous message to save energy.

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