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Re: HILTI Anchor for anchoring Vessels

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Bill,

Neil, too, brought my attention to the ICC Reports. Thanks to both of you as well as to others who shared their views.

I found something interesting about the ICC Report vis-a-vis HILTIs' published tables for HVA adhesive anchors. The allowable loads listed in ICC are smaller than what HILTI allows. In addition, the adjustment factors  for edge distance and anchor spacing are also more conservative in ICC tables. Furthemore, the tension-shear interaction formula recommended by ICC will yield a larger number in comparison with what would be calculated from HILTI's. In essence, ICC's recommendation has conservatism built in at three stages of the calculation. I was told by HILTI representative that ICC, for whatever reason, typically, adopts a higher factor of safety (obviously!). I was also told that ICC does not conduct any test or study on its own. It, simply, takes the ultimate values provided by HILTI (HILTI runs its own test program) and comes up with allowable values!

HILTI did not make a final recommendation except to say that the engineer is bound by the directive of the controlling permitting agency, if any, or by the code dictated by the client. If the client does not care or, if permitting is not involved, the engineer is free to use whatever he takes fancy to! That was comforting!

I am positive that such anamolies may exist between any other ICC report and the corresponding vendor data. I thought this information will be useful for the list members.

Rajendran

bcainse(--nospam--at)aol.com wrote:
Rajendran-
Go to the ICC website and download ESR-1702 for Covert Operations, Inc. products. DUC values are in Tables 15 through 19.
Bill Cain, S.E.
Berkeley CA
 
 
-----Original Message-----
From: Padmanabhan Rajendran <rakamaka(--nospam--at)yahoo.com>
To: seaint(--nospam--at)seaint.org
Sent: Fri, 17 Mar 2006 12:41:48 -0800 (PST)
Subject: Re: HILTI Anchor for anchoring Vessels

Harold,

Thanks.

1. I did not see any tables and charts to design Covert, Undercut anchor at their web site. Does it mean that I prescribe the loads and the Company designs on a case by case basis?

2. Hilti recommends tensioning epoxy anchors. So, what may be your objections to it?

Rajendran

Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:
I have used a Covert "Ductile Undercut Anchor" post installed mechanical
anchor rod and tensioned the anchor rods after installation.
http://www.covertoperationsinc.com/duc.html
On the applications that I have employed, the bolts were checked after a
week and showed no relaxation.

I would advise against tensioning an epoxy anchor.

Regards,
Harold Sprague

>
> ----- Original Message -----
> From: Padmanabhan Rajendran
> To: seaint(--nospam--at)seaint.org
> Sent: Friday, March 17, 2006 6:58 AM
> Subject: HILTI Anchor for anchoring Vessels
>
>
> A client wants to set a vessel (8' dia X about 55' tall) on an existing,
>2' thick, concrete mat, and anchor the vessel to the mat with 1" dia HILTI
>epoxy grouted anchor rods. The tension and shear in the bolt is 11000 lbs
>and 1000 lbs respectively. My scope of work is to determine the bolt
>embedment depth. I understand that the bolt will be pretensioned after the
>vessel is installed.
>
> I used the published values of nominal bolt loads, adjustment factors
>for edge distance and bolt spacing etc. to calculate the bolt embedment
>depth. One of the standard embedment lengths (12.375") is sufficient to
>support the vessel.
>
> What bothers me is that the post-installed epoxy anchors are not
>approved by ACI 318 (See Appendix D for Scope of application) mainly
>because the reliability of these type of anchors has not been certified in
>accordance with ACI 355.2. However, the published bolt values in HILTI
>catalog have been certified, by ICC Evaluation Service, to conform to UBC
>1997, and 2000 IBC. The certification stipulates that it is valid only when
>the concrete is uncracked. The restriction stems from the fact that the
>anchors were not tested in cracked concrete environment.
>
> The current thinking in anchor bolt design is that the headed bolt, or
>something similar, is the most effective anchor element. It is reported
>that L- shaped and J-shaped bolt perform poorly, in comparison. If L-shaped
>and J-shaped bolts perform poorly, how can a straight piece (despite having
>threads) perform any better?
>
> Is it possible to pretension an, un-sleeved, anchor bolt? Is it not
>likely that concrete near the surface will crack?
>
> Please share your thoughts and experiences, if any.
>
> Thanks.
>
> Rajendran
>
>
>------------------------------------------------------------------------------
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