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Brian Payne, AIA
Senior Member
Username: brian_payne

Post Number: 41
Registered: 01-2014


Posted on Tuesday, June 10, 2014 - 03:30 pm:   Edit PostDelete PostPrint Post

I am looking for any recommendations on a system to horizontally support 4 inch thick limestone to match the wall construction. Any suggestions?
George A. Everding, AIA, CSI, CCS, CCCA
Senior Member
Username: geverding

Post Number: 751
Registered: 11-2004


Posted on Tuesday, June 10, 2014 - 03:39 pm:   Edit PostDelete PostPrint Post

What does the ILI Handbook say? I know at one time it had some recommendations for gravity loading in soffit and similar situations.
Liz O'Sullivan
Senior Member
Username: liz_osullivan

Post Number: 149
Registered: 10-2011


Posted on Tuesday, June 10, 2014 - 03:42 pm:   Edit PostDelete PostPrint Post

Kahn would say to "honor the materials that you use." But that doesn't help at all, does it?
Wayne Yancey
Senior Member
Username: wayne_yancey

Post Number: 655
Registered: 01-2008


Posted on Tuesday, June 10, 2014 - 03:50 pm:   Edit PostDelete PostPrint Post

Brian,

Go to http://www.halfenusa.com/ for inspiration. Halfens soffit anchors may work for stone.

Also check the Marble Institute of America manual.

Wayne

Wayne
Robert E. Woodburn, AIA, CSI, CCS, CCCA
Senior Member
Username: bob_woodburn

Post Number: 88
Registered: 11-2010
Posted on Tuesday, June 10, 2014 - 04:03 pm:   Edit PostDelete PostPrint Post

I asked the stone what it wanted to be, and it said, "I like bedrock..."

(apologies to Kahn...)
ken hercenberg
Senior Member
Username: khercenberg

Post Number: 772
Registered: 12-2006


Posted on Tuesday, June 10, 2014 - 04:26 pm:   Edit PostDelete PostPrint Post

Halfen has a great system but it costs. A lot.

There are a number of options available. See Cold Spring Granite, Hohmann & Barnard, and similar firms for their stone anchoring systems. MIA and ILI do have some useful details but they may not be all-inclusive of some options offered by manufacturers.
spiper (Unregistered Guest)
Unregistered guest
Posted on Tuesday, June 10, 2014 - 05:57 pm:   Edit PostDelete PostPrint Post

Depending on the quantity of the soffit and the timeframe of the project you could consider reducing the weight of the soffits by going to a composite panel at these locations.
Stone Panels, Inc. can do thin stone panels from the same material and the same quarry and they will be much easier to mount. They are not cheap and they have a long lead time but it may help you rest easier.
ken hercenberg
Senior Member
Username: khercenberg

Post Number: 773
Registered: 12-2006


Posted on Tuesday, June 10, 2014 - 07:55 pm:   Edit PostDelete PostPrint Post

Oh, and whatever system you use, don't use chemical anchors.
Edward J Dueppen, RA, CSI, CCS, LEED AP
Senior Member
Username: edueppen

Post Number: 8
Registered: 08-2013
Posted on Wednesday, June 11, 2014 - 08:43 am:   Edit PostDelete PostPrint Post

Ken, you roused my curiosity. Why not chemical anchors?
ken hercenberg
Senior Member
Username: khercenberg

Post Number: 774
Registered: 12-2006


Posted on Wednesday, June 11, 2014 - 10:33 am:   Edit PostDelete PostPrint Post

After the fiasco at the Big Dig where the chemical anchors in an overhead application failed horribly, there was backlash about putting chemical anchors in permanent stress/tension applications such as heavy soffits.

It may be overkill, and maybe the anchor manufacturers have changed their stance again since then, but right after it happened I was instructed to avoid it by structural engineers and folks like Hilti.
George A. Everding, AIA, CSI, CCS, CCCA
Senior Member
Username: geverding

Post Number: 752
Registered: 11-2004


Posted on Wednesday, June 11, 2014 - 11:52 am:   Edit PostDelete PostPrint Post

Hilti did the corrective work on the tunnel failure. I heard that the issue wasn't anything intrinsically wrong with chemical anchors, it was in the installation and quality control. If you aren't relatively precise in drilling the hole, and most important, if you don't clean the dust out first, you don't achieve the design structural capacity.

Hilti's fix used an expansive anchor (perhaps with adhesive as well, I don't exactly remember) so they had a mechanical means to resist the gravity load. Like Ken, I don't know where they are now with their recommendations, but the point to take away - installation is perhaps more important than product in this application.

I second the recommendation about Halfen - they can solve a myriad of tricky structural connections. True about the cost of their systems. On the other hand, a lawsuit resulting from falling limestone could be a bit expensive too, eh?
Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate
Senior Member
Username: lynn_javoroski

Post Number: 1829
Registered: 07-2002


Posted on Wednesday, June 11, 2014 - 12:01 pm:   Edit PostDelete PostPrint Post

Read about a falling concrete panel here:

http://www.nbc15.com/home/headlines/UPDATE_Milwaukee_Garage_to_Reopen_Year_after_Accident.html

Yeah, a bit expensive.

Lynn
Wayne Yancey
Senior Member
Username: wayne_yancey

Post Number: 656
Registered: 01-2008


Posted on Wednesday, June 11, 2014 - 12:24 pm:   Edit PostDelete PostPrint Post

Pay attention to George's last comment. You get what you pay for. We are to poor to buy cheap.
ken hercenberg
Senior Member
Username: khercenberg

Post Number: 776
Registered: 12-2006


Posted on Wednesday, June 11, 2014 - 12:50 pm:   Edit PostDelete PostPrint Post

To my understanding the failure in the epoxy was due to cold flow (creep) which occurs over time. See http://en.wikipedia.org/wiki/Big_Dig_ceiling_collapse for a wiki post about it.
George A. Everding, AIA, CSI, CCS, CCCA
Senior Member
Username: geverding

Post Number: 753
Registered: 11-2004


Posted on Wednesday, June 11, 2014 - 12:55 pm:   Edit PostDelete PostPrint Post

I wanted to clarify my previous comment which wasn't entirely clear - there isn't anything intrinsically wrong with chemical anchors, assuming you use the right anchors and install correctly with proper testing and quality control. There were issues with the epoxy used in the ceiling collapse as Ken stated. Read about it in the NTSB report:

http://www.ntsb.gov/doclib/reports/2007/HAR0702.pdf
Edward J Dueppen, RA, CSI, CCS, LEED AP
Senior Member
Username: edueppen

Post Number: 9
Registered: 08-2013
Posted on Wednesday, June 11, 2014 - 01:15 pm:   Edit PostDelete PostPrint Post

George - thanks for sharing this document. I have a new understanding of the limitations of epoxy anchors.
Mark Gilligan SE,
Senior Member
Username: mark_gilligan

Post Number: 665
Registered: 10-2007
Posted on Wednesday, June 11, 2014 - 01:29 pm:   Edit PostDelete PostPrint Post

These suspended systems need to be designed by a registered engineer. While the detailed design may be delegated the engineer designing the building should make sure that the structure can accommodate a reasonable design strategy.

There are special code provisions related to the installation of adhesive anchors that suggests that any specification for their use be reviewed if not written by somebody who is familiar with the code provisions.
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick

Post Number: 1577
Registered: 03-2002
Posted on Wednesday, June 11, 2014 - 06:24 pm:   Edit PostDelete PostPrint Post

In the case of the failure on the Big Dig (in my fair city), it was reported to be cold flow as Ken mentioned. (There were several structural engineers involved in the design and construction of these anchors.) There were some lawsuits about whether the formulation was appropriate, and whether the manufacturer's recommendations were followed or correct. My own take on that issue, after reading about it, was this was a bit of a red herring; but I don't know what the courts concluded. It also seemed to me that there was not much redundancy in the system, allowing for progressive collapse - one anchor no longer carrying any load led others nearby to be significantly overloaded. The fix was to use mechanical anchors as mentioned above. I believe there were some code changes made after this incident to address the issue.
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick

Post Number: 1578
Registered: 03-2002
Posted on Wednesday, June 11, 2014 - 06:30 pm:   Edit PostDelete PostPrint Post

My post above was about the collapsing concrete ceiling panels. But the Big Dig also had a failure of lighting fixture attachment after that, which probably did not get much national publicity. In that case; there was corrosion between stainless steel attachment hardware and the aluminum of the fixture (or something quite similar.) In this case, it seemed like the choices made for alloys and materials should have worked, but in the damp (and I suppose polluted) environment of the tunnel - not so good. No one was hurt in this case.

I'll skip the story about the excessive water infiltration.
anon (Unregistered Guest)
Unregistered guest
Posted on Wednesday, June 11, 2014 - 05:59 pm:   Edit PostDelete PostPrint Post

you might consider using a thin stone of the type/variety you want over a lightweight core material - Thin Stone Systems makes a very nice version of this (there are a few others), and they provide engineering and details for fastening.

http://www.thinstonesystems.com/

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