Glass Guard Approval

[CANeng11]

I've been asked if I would be able to approve the attached glass guards (is balustrade the correct term?). I've never come across this before and I wanted to ensure I knew what all the considerations are for these designs. Looking through the code (Canada), it appears that the critical information is that it needs to be able to withstand certain minimum specified loads (0.5 kN/m or 1.0kN at any point, as well as 1.5 kN/m applied at the top of the guard) and that it must be safety glass of the laminated or tempered type conforming to CAN/CGSB-12.1-M. Now, I can easily check the capacity of the connection for the applied loading, but I feel that checking the glass is trickier (or at least something I don't have experience in). Does anyone have any experience with these types of guards? Anything I am missing?

 

[jayrod12]

If my memory serves me correctly the one tricky item we've had designing glass guard is the canadian glass code requires a top rail where glass is being used as guards to act as a alternative load path if a single lite is broken.

I don't know if they've changed that requirement, haven't had to do one in a while.

 

[MIStructE_IRE]

Cool house! Although glass balustrades would not work with my crazy kids.. Similarly, that sharp corner on the glazing should be reviewed by H&S guys. That’s gonna hurt..

I usually see FE done for Point supported glass. You obviously have large stress concentrations around these supports so i’m not sure how you’d go about it with any degree of justifiable accuracy without FE.

In my experience this would typically need to be 19mm toughened laminated glass. This looks quite thin?

Just from looking at this, I would also have my doubts about the floor level balustrade glazing and its connections. Edge distance/base material/glass design stresses - all need to be checked thoroughly.

 

[CANeng11]

The glass is only 12mm thick. We don't have the capability to run a FEA on this. This is a good client, so we obviously don't want to tell him we can't do this for him, but it's looking that way maybe.

 

[CANeng11]

jayrod12... I wasn't able to find any reference regarding the top rail requirement. Maybe it was taken out as you said.

 

[MIStructE_IRE]

Jayrod, we have that requirement here also.

 

[Brad805]

You need to look thru Part 9 if this is in a house. The clause Jayrod mentioned is in Part 3 if I recall correctly. We had a go around with a client over that. The break in the handrail at the mid landing is another potential problem, but I do not recall if Part 9 allows that. If the building inspector has passed the life safety aspects I would look at the specific questions being asked. CR Laurence is a common supplier for the standoffs and they have tables. As for the glazing, I am curious why that is not kicked back to the supplier?

It looks like they used lags for the mounts at the main floor. I suspect they would have been supplied a stainless steel bolt, but that is not as simple as lags.

 

[jayrod12]

Found it. It appears that is when the glass is only designed as interior fit panel. It would appear that b)i) would allow you to proceed without a top rail. But in my experience, the glass needs to be quite thick in that case. I believe the new Oilers Arena in Edmonton has cantilevered glass guards everywhere and it is 1" thick (approximately I don't have access to the documents directly).
CSA-A500-16 Building Guards

 

[EdStainless]

The rating of the glass should be etched into the corner of the pieces.
I hope that this is a pre-engineered system from a company that makes these for a living.
If so then they should have detailed information about conformance.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[CANPRO]

Were you there in person to check this out? If so, did you put it to the test? Giving a railing a good sturdy shake isn't by any means going to validate the design, but it sure can invalidate it in a hurry.

 

[Dvdt18]

As EDStainless said, most of the glass guards we design have the stamp in the bottom corner. Perhaps they have an invoice with more spec's on the glass?

If the hardware is from C.R. Laurence, you may be able to find detailed spec's here

http://www.crlaurence.ca/apps/conte...ce.ca/datasheets/testreports/testreports.html

 

[JLNJ]

You might want to do a series of real pull tests in the field since your calculations will probably show several of the components don't work.

 

[StrucPEng]

If you are looking to run an FEA I would suggest SJ Mepla. It is designed specifically for glass FEA, created in Germany who are arguably leading in structural glass design. They do offer a trial version of the software as well.

https://www.mepla.net/en/

Just based on the size of glass you noted (12mm monolithic) you might have a hard time justifying it working for guard loads. This looks residential so that is helpful but you will have some pretty high stresses at the point fixing holes at the bottom and at the handrail which has to be checked as well for its own loads and effect on the glass. Usually for balustrades we have specified laminated glass with a stiff SG inter layer. Benefit of the inter layer is you can usually justify not having a top cap as the inter layer is usually stiff enough for short term loading to resist glass breakage. If the mono lights break there is nothing other than the handrail to transfer that load into adjacent panels.

Good video showing the difference between mono glass and laminated glass (

https://www.youtube.com/watch?v=FZYlUbrIhps)

As far as I know A500-16 has not been adopted by the building code as a reference standard. We have had issues with building officials in the past where they did not require a top rail and others where they required one full stop.

 

[Pmtottawa]

Sure hope your project isn't in Ottawa.
I've dealt with them on numerous projects and fail anything that doesn't have a top rail.

 

[NorthCivil]

CANeng11

I'm a glass guy and have worked in Canada.

1. From your post. "I've been asked if I would be able to approve the attached glass guards" "something I don't have experience in"

If you don't have experience in this, why would you run the risk of approving something you know nothing about?

2. I can tell straight away, by the photos, this arrangement looks non compliant in many ways. Very dodgy.

3. "This is a good client". well, your good client is asking you to risk your neck to allow them to avoid fixing a costly mistake.

I've been called out to sign off on quite a few guardrails looking like this. I will give them the repair methods, though I rarely get called out to inspect the repair. They usually find another sucker who doesn't know much about glass to rubber stamp it. You are being asked to be the rubber stamper.

here is some reading for you if you have any spare time:

https://www.egbc.ca/getmedia/6a9595...-technical-Ahmed-Syed-for-publishing.pdf.aspx