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Re: Anchor bolt sleeve - Pretension force

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1. Current understanding of the mechanics of embedments in concrete is that 
 "bond strength" was never reliable in the first place and isn't used in 
considering anchorage.

2. The old "bond break" theory represented by the use of sleeves etc. 
represents an obsession with a mechanism that was always trivial though we 
didn't realize how trivial at the time. I haven't used AB sleeves in twenty 
 years, but I've worked in the energy industry, where they do things because 
 "that's the way the guy who trained me did them."

3. I've found that for pretensioning of headed bolts for mechanical equipment, 
 the critical factor is bearing on the head, 99.9% of the time.

(FOOTNOTE: torque ratings of bolts to equivalent pretension values is absurdly 
 inaccurate; the statistical correlation is around 50%. Turn-of-the-nut is 
better but by no means accurate. I use "DTI sandwiches" for pretensioned 
equipment anchor bolts).

William L. Polhemus, Jr. P.E.

6

> On Oct 2, 2015, at 10:02 AM, Vasu, Ravi <Ravi.Vasu(--nospam--at)jacobs.com> wrote:
> 
> List,
> 
> I have an anchor bolt case for  a compressor foundation done recently. 
> A sleeve, 2 ft long is provided at top for a 2.5" dia(A354, Grade BC), 6.5 
> ft long. The bond breaking tape below the sleeve is missed by construction. 
> The anchor bolt needs to be pre tensioned for 125 kips for 2.5 inch dia 
> bolt suggested by compressor vendor. I have gone through several articles. 
> One of the articles by Rick Drake(Fluor) says,  Sleeve at top is sufficient 
> for the stretching of the bolt.  My concern is the concrete below the 
> sleeve may go through some cracks (bond strength available is small < 20 
> kips) before the cone action starts from the bottom nut of the A bolt to 
> counteract the pretension force.  If sleeve is sufficient(need back up 
> tech. article), how much length is required?.
> 
> Let me know your thoughts on this.
> 
> Thanks
> 

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