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Glass used as walls
2

Glass used as walls

Glass used as walls

(OP)
since most clients choose glass walls to be installed for residential house, what are the remedies (structural design) to resist lateral forces?

RE: Glass used as walls

Moment resisting frames, or cantilevered columns. Or else, talk the client or architect out of some of the glassed area so as to provide some shear walls. Or provide cross bracing across the glass, a solution which some like and some don't.

RE: Glass used as walls

You can also utilize interior shear walls to take the place of the glass walls laterally. Thee sided shear wall systems are an option too, albeit a contentious one. For both schemes it is prudent to keep an eye on the drift at the glass wall.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

Impressive picture glass, got any details on that sort of system? What provides the lateral resistance for the structure?

Maine EIT, Civil/Structural.

RE: Glass used as walls

Quote (TehMightyEngineer)

What provides the lateral resistance for the structure?

The 2x4's, silly. smile

RE: Glass used as walls

Oh, of course. ;)

Maine EIT, Civil/Structural.

RE: Glass used as walls

It may well be the glass that resists the shear loads. With appropriate attention to reliability, that kind of thing is very much on the table nowadays.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

No kootk, no it is not... If your material is wholly brittle, you should very much NOT be using it as a cyclical loading resistance system. Not at all reasonable, IMHO.

Glass: Very impressive... Is this a non-EQ zone? Otherwise how did you address post-EQ reliability?

RE: Glass used as walls

A few points:
- glass is infinitely strong in compression
- structural silicone between panels makes the panels work together in plane as a pretty effective shear wall
- there was another concrete shear wall out of the shot.
- project was in Santa FE, NM
- it was laminated glass and had other layers of redundancy built into the concept.

See attached for another glass wall building, actually with a glass beams and a glass roof also. We completed in Times Square NYC in 2008.

RE: Glass used as walls

Glorious Glass99. Are you familiar with the work of John Kooymans? I got to peer review some of his work back when we shared an employer. That's how I came to be a believer in glass as a serious structural material.

I firmly believe that structural reliability methods properly applied to brittle materials can produce structures with the same level of safety that can be had in ductile construction. It takes more skill but, then, we've got the technology.

Post-Christchurch, some are even starting to question if ductility is really even all that great. Preventing collapse is nifty but having to demo half your building stock is not. This manner of thinking is consistent with performance based design principles. Any material can be put to work so long as its limitations are respected.

I'm currently reading a book called "the stone skeleton". It's about the structural design of brittle,unreinforced, mortarless masonry and stone. Safety factors are based on geometry in that world rather than stress or ductility. There are cathedrals built using these principles that have survived major earthquakes, heavy WWII bombing, and foundation settlements that would get a modern building condemned.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

Wow... I would not have expected glass to be a reasonable lateral system. Laminated or not, we're talking about catastrophic failure here is anything goes wrong.

I'm really not sure I'd ever want to have at something like that.

RE: Glass used as walls

Well, so far, "within its limitations" seem to amount to one story, low importance buildings for which cost is not a primary driver. And the considerable redundancy involved extends far beyond lamination. Glass99 will likely be able to do it better justice but you'll often see redundant walls, redundant laminations within walls, and nifty details to allow for easy, anticipated wall replacement.

We are talking about a material that sort of spontaneously explodes for no reason after all. Nobody's pitching high rise elevator shafts in glass just yet. Although I'm sure there's some maniac at Delft looking into it for after CLT skyscrapers get boring.

Other than the odd guardrail, I leave glass design to the experts. As a material, it's not nearly forgiving enough to accommodate the fumblings if a uninitiated hack.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

Yup... Nickel Sulfur inclusion if I remember right. Something like 1 in 10000 fail because of the stress from the crystal inclusion.

The interesting thing about the tempered glass in the code is the apppication / new requirement for heat-soaked tempered if you are not wanting to use other laminates. Heat soaking encourages those panels with inclusion(s) to fail. They don't always fail during the heating and cooling, but the inclusions tend to have grown and this makes the panel even more likely to fail catastrophically.

RE: Glass used as walls

I'm not sure I would like to live or work in a goldfish bowl. There's no place to blow your nose in privacy. And I'm glad I don't have to wash the windows.

BA

RE: Glass used as walls

Something about stones comes to mind as well. :P

Maine EIT, Civil/Structural.

RE: Glass used as walls

To each his own, bridgebuster. It wouldn't appeal to everyone.

BA

RE: Glass used as walls

it shouldn't. The hotel could put up a sign "now you know what it's like in the army."

RE: Glass used as walls

What is the R factor on silicone caulking? It is pretty ductile....

There was an article in a recent Modern Steel Construction where they talked about connecting the glass pieces together to act as a shearwall at some new buildings at Colorado School of Mines, but it had a steel gravity load system.

Glass's 1st pic is cool, but I would be scared with snow and window buckling the skinny brittle glass wall. But then that is why I don't design in glass.

RE: Glass used as walls

Funny dcarr, I was just thinking that I'd possibly be okay with this if a procedure such as the system redundancy typically used in parking garage structures was employed...

What I'm thinking is that the system would be required to meet ULS requirements in absence of all glass, possibly at a reduced load combination like 1.2D + 1.0L.

Using it for seismic only and having a full gravity system would seem reasonable, so long as we are talking about VERY robust glass systems.

Glass99: What type of glass panes would you be recommending for this kind of work? It makes me think of the polycarbonates I used in antiterrorism work. Lay up tempered on two faces with polycarb perhaps?

RE: Glass used as walls

To all you with brittleness on your minds: would you design with stone or unreinforced masonry? Glass structures are way more engineered in respect to redundancy and progressive collapse than the typical brick wall that's perhaps holding up the roof over your head right now. -> its all about engineering around the brittleness.

In terms of impact, its not that hard to break the outer ply, but breaking subsequent plies takes a really substantial whack. Its more in the scale of multiple sledgehammer blows.

Nickel sulfide is not the thing it used to be. The float lines have really cleaned up their acts in respect to sulfur content. Also heat soak testing goes a long way. CELinOttawa: Cardinal had a widely cited study which spooked a bunch of folks about heat soaking in the US. People are getting over that now, primarily because heat soaked glass rarely gets NiS breakages. Its not 1995 any more!

KootK - yes I know John Kooymans from conferences mostly.

RE: Glass used as walls

CELinOttawa: Bullet resistant glass has a polycarbonate core with glass on the outboard plies. I would not use this in a structural application typically, though you could. Its not as strong as all glass, plus the varying stiffness and coefficient of thermal expansion between polycarbonate and glass creates its own issues. Polycarbonate is actually much more brittle than people realize. Also bullet resistant glass is expensive. Simply tempered or heat strengthened glass, laminated with an SG interlayer is the right answer in practically all applications. The glass is one thing but a large part of the design is the connections and the structural system.

RE: Glass used as walls

Glass,

I think your analogy is a poor one. Unreinf masonry/stone often relies on its own weight and a thick cross section to keep stresses low. In that 1st pic it looked like the glass was the gravity load system as well. P-delta under some combinations and low out of plane buckling strength were my concerns. Clearly it can be done though.

RE: Glass used as walls

dcarr: yes, its all about buckling where there's compression. Though buckling and P-Delta are easy to calculate. Glass is a linear elastic material just like steel. Pick a factor of safety and go for it! Its actually an easier calc than steel because there is no futzing with plastic hinges.

RE: Glass used as walls

Yeah, my book on stone makes the same point. One of the assumptions of design is that reasonable proportions make stress irrelevant.

The part of glass design that really unmans me is discrete bolted connections. I think that connections is where the lack of ductility is the most dangerous. FEM on a bolt hole with the requirement to "know" maximum stresses is a scary prospect.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

KootK - holes in glass are actually somewhat against nature. Done properly, they are gigantically strong - you break the bolt before you break the glass. Miss something about an imposed rotation or something and you are screwed! You may note that the Santa Fe house had no holes.
-> I like to tell clients - Glass is a fickle mistress. She wants the soft touch of the Spanish lover, not the rough hand of the Russian sailor.

RE: Glass used as walls

Glass99,

I don't really do any work in glass but I am infinitely curious about using glass as a structural element and its design. What approach or design guide/manual do you typically follow? It seems like every design needs extensive FEA and testing outside of typical store front or curtain wall design. Do you work for a glass contractor or do you specialize in glass design, if you don't mind me asking. I'm just curious who does these type of designs.
I've read the book "Structural Use of Glass" by Matthias Haldimann which suggests a new approach to designing glass I think it was called the lifetime prediction model. I'm curious if that is used in practice?

Thanks!

EIT
www.HowToEngineer.com

RE: Glass used as walls

RFreund: I am a consulting engineer, and have a small practice in NYC. I do work for contractors, owners, and architects. There are basically no code or books to follow, though there will be an ASTM for structural glass released at some point in the next few years, and there are some EuroNorms. I use first principles mostly and use finite elements for most designs. Personally, I hope there never is a code, because it will restrict use.

RE: Glass used as walls

Interesting.
Not to start a readit/ama but....
How did you get into glass design?

EIT
www.HowToEngineer.com

RE: Glass used as walls

(OP)
Thank you guys,

RE: Glass used as walls

(OP)
Kootk, i'm thinking of installing interior shear walls but i'm wondering since i've read a note that interior shear walls does not resist lateral force

RE: Glass used as walls

Glass structures are very impressive. I have not designed anything in glass, but do know that the Institution of Structural Engineers publishes a guide book, "The structural use of glass in buildings".

IStructE Structural Use of Glass In Buildings

RE: Glass used as walls

Glass99 -> A few more questions (my apologies to the OP. I should probably start a new thread, I could be here all day or until you invite me to your office for bring your favorite eng-tiper to work day)

In regards to point glazing being very particular. Do recieve design properties to use in your FEM model from the point support manufacturers or is there somewhat of a standard? Is there much testing involved when you design these glass supported structures to verify these FEM models? I imagine there being many FEM models for just about each different piece of glass, do you guys have some sort of library of glass units that you modify? Sorry, all very fascinating to me. My father-in-law actually owns a small glass company, I've had distant dreams of constructing a glass bridge. upsidedown

EIT
www.HowToEngineer.com

RE: Glass used as walls

What role do you play on this project Lampi2k? Who's note is it that you've mentioned? I'd look into it. A note stating that shear walls don't resist lateral loads does't make much sense to me. What's the exact wording? Maybe there's a distinction between in plane and out of plane lateral loads.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

Glass99,

Can you give us some shear values on that silicon product that you are stating makes your panels act like a shear wall? Pretty incredible photo by the way. Every architects dream. Also, I have never seen an infinitely strong allowable compressive stress in a material, except on my home planet of Krypton. Do you have some glass charts we could see with the allowable stress set to "infinity".

RE: Glass used as walls

This reference discusses that BigMig: Link

On a fibre by fibre basis, glass is stronger than most steel. It's only imperfection induced fracture mechanics stuff that reduces the strength drastically in tension.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Glass used as walls

Structural silicone has an allowable stress of 20psi for short term loads, which includes a factor of safety of approx 5 to 15 depending on the exact silicone.

There is technically a compressive strength of glass, but it is close enough to infinity. Its of the order of 1000ksi. Failure in compression structures is always a function of secondary tension stresses like poisson's ratio effects or buckling.

RE: Glass used as walls

(OP)
my apologies Kootk, it was a misinterpretation on what i've read. By the way, glass99 do you have a reference book that i may refer regarding strengths and stresses of structural glass? thanks

RE: Glass used as walls

Fascinating discussion.

RE: Glass used as walls

No sweat Lampi. Ussuri's recommendation above is a good start. This is also an excellent, popular, modern reference: Link

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

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