Glass Calculation - Laminated: 3 lites Fully Tempered, 2 layers PVB

[JNEnginr]

Hey,

I was going to post this in the glass section of the site, but it looks like no one's been there since 06/2016, so here i am.

Anyone have any experience with design Tempered Laminated Glass that is 3 lites thick with 2 layers of PVB in-between?

E1300 Section 6.2.5 has it for singly glazed LG, but my situation seems a little different. Do i just distribute the load?

Thanks in advance.

 

[KootK]

For high temperatures and long duration loads, you'll probably treat it as three non-composite lites. For other conditions and composite behavior, from the IStructE document:

What is the intended use of the panel? Three laminated is unusual so I'm guessing it's something like floor. Depending on the use, it may be wise to consider one or more layers to be sacrificial or non-participating for reasons of redundancy, fire performance, etc.

Hopefully member NorthCivil shows up on this one. I know that he has extensive experience in this area.





I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JNEnginr]

Thanks so Much!

Yes, its for a Canopy , and it seems like its overkill. 1/4"FT-1/8"PVB-1/4"FT-1/8"PVB-1/2"FT

I've seen NorthCivil posts in the Glass section so i concur that i hope he chimes in.

Also, what happens when the glass inst supported continuously along all 4 edges, but rather at the 4 corners, with the 4 way arm mounts. Anything special to consider there?

 

[KootK]

Point support will result in localized stresses at those supports likely being the dominant concern with regard to ultimate capacity. That, instead of midspan bending etc. Additionally, you'll want to give consideration to proper edge distances etc given the nature of the hardware and tolerances etc. While I've not read E1300-16 cover to cover yet, I do believe that point support invalidates the use of that document for design.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JNEnginr]

Are you aware of another document that does cover said design?

 

[KootK]

Well, I should rephrase that. You can use E1300 for composite glass properties etc in many instances. You'll just need to work out the stresses by some means other than those handy charts.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[klaus.]

Hi
are you using a FEA Model to do the stress calculation ?
As KootK said...you can treat it as 3 single lites ... load share according to the stiffness of each lite
it is a pretty thick glass ( 1 inch in total )... so I guess the deformation might govern the design




best regards
Klaus

 

[JNEnginr]

Originally I was looking to use E1300 but i don't think it's appropriate anymore so im guessing FEA Model might be the best, if not only, way to go.

I agree that deflection is going to control as well, i just want to know the correct way of going about this.

 

[klaus.]

The interesting Question is, what is the allowable stress that you compare the results of FEA with ??

The USA codes and regulations do not give any decent values because the glass 'codes' are not made for FEA Calculation






best regards
Klaus