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Re: HILTI Anchor for anchoring Vessels; now Covert.[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>, seaint(--nospam--at)seaint.org
- Subject: Re: HILTI Anchor for anchoring Vessels; now Covert.
- From: Neil Moore <nma(--nospam--at)omsoft.com>
- Date: Fri, 17 Mar 2006 13:25:18 -0800
Go to the ICC website and download Covert's ER-4846 Legacy Report, which should provide you with the allowable shear and tension capacities for various configurations. It is a 17 page .pdf file. On some powerhouse projects, Covert is the required anchor.
Neil Moore, SE, SECB
neil moore and associates
shingle springs, california
At 12:41 PM 3/17/2006, Padmanabhan Rajendran wrote:
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?
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.
- 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.
- Harold Sprague
- > ----- Original Message -----
- > From: Padmanabhan Rajendran
- t; 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 t he surface will crack?
- > Please share your thoughts and experiences, if any.
- > Thanks.
- > Rajendran
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