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Re: big dig structural failure - epoxy anchors overhead supporting gravity

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>>By the way Bob--how much better is
brush-blow-brush?<<<<

Brush blow brush is WAY better.....finishing up with "blow" reduced capacity by 30%+  in my expeience YMMV. 
My brilliant idea of blowing last was a totally bad idea. 

Check out the Hilti design / application guide & use their recommended procedures,  I have a lot of faith in their work.

Poorly prepped holes can reduce chemical anchor capacity by 50%.

I think SImpson reudces their values depending on hole cleaning method, they even have a value for "no cleaning" but I'm sure there is a huge scatter on those values & I'd be reluctant to use those values.

Proper cleaing, if you've got the right tools & process. isn't all that hard.

BTW I typically vacuum as I drill so the subsequent "blows" are much less messy, most of the drilling debris is already gone.

So my process is drill & suck, brush, blow, brush


cheers
Bob

On 7/15/06, chuck utzman < chuckuc(--nospam--at)pacbell.net> wrote:
Epoxy creep?
I like simple explainations myself--dirty holes as Bob K. suggested
sounds more likely.  By the way Bob--how much better is
brush-blow-brush?  As long as I'm going to observe the process, I might
as well get the best procedure.
Around here the Building Dept. is starting to require a  Special
Inspector (in addition to the EOR) to observe epoxied tiedown bolts (it
comes up ferquently in remodeling work).  Comments?
Chuck Utzman, P.E.

Ray Pixley wrote:

> Guys.  Play nice.
>
> The vibration argument is probably a red herring.  Has anybody had
> thoughts on epoxy creep?  Perhap in combination with fatigue?
>
> ----Original Message Follows----
> From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
> Reply-To: <seaint(--nospam--at)seaint.org>
> To: <seaint(--nospam--at)seaint.org>
> Subject: Re: big dig structural failure - epoxy anchors overhead
> supporting gravity
> Date: Sat, 15 Jul 2006 16:34:42 -0500
>
>
> On Jul 15, 2006, at 4:15 PM, S. Gordin wrote:
>
>> Now, if I place a sandbag on it - the vibrations will be much less
>> without adding any rigidity to the system, just because of the
>> increased mass.
>
> Again, I don't see how that works, except if the decreased frequency
> due to the added mass is enough less than the frequency of the
> excitation of the fan. And you could get the same effect if you were
> to stiffen the deck, say by adding a support.
>
> The frequency of a flat slab carrying only its own weight is
> proportional to the thickness and inversely proportional to the square
> of the span. You get more bang for the buck by adding supports than
> you do from adding thickness. Adding thickness means using stronger
> supports, but adding supports decreases the load per support.
>
>> If those panels would be made of, say, steel decking, they will
>> vibrate; fill the deck with concrete - for all practical reasons,
>> they won't.
>
> I wonder if the purpose is to use the mass to hold them in place
> against uplifting from the pressure wave. Strictly speaking that isn't
> vibration, it's rigid body motion. Otherwise I think I'll stick to my
> guns.
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
> .......................................| John Sedgwick, Spotsylvania
> 1864)
> http://www.skypoint.com/~chrisw/
>
>
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