I'm not at all surprised by the glass failing; it's a common problem in tall buildings, where stresses build up over time from building settling or movement, and the mounting has only so much compliance. My son lives in a 8 story condo and most of his front facing windows are cracked.

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Is there an issue with tempered glass slowly relaxing the built in stresses over time, since glass is considered a 'supercooled' liquid. I understand some medieval stain glasses have 'flowed' a tad, and created an opening (Myth... see below).

-----*****-----
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-Dik

Quote:

I understand some medieval stain glasses have 'flowed' a tad, and created an opening

That's a myth https://engineering.mit.edu/engage/ask-an-engineer....

Tempered glass is probably even less likely to flow, given the amount of internal stress it has.

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thanks IRS... didn't know that. Excellent link...

-----*****-----
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-Dik

Quote (Tempered glass is probably even less likely to flow, given the amount of internal stress it has)

Given the amount of it, can the internal stress, relax over a period of time?

-----*****-----
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-Dik

There have been some high rise glass failures due to nickel sulphide inclusions. I think there will be an investigation, which will find the cause in this case.

Quote:

Given the amount of it, can the internal stress, relax over a period of time?

As the article indicates, glass is not a "supercooled fluid", but an amorphous solid, i.e., it has no general or pervasive crystalline structure, but has, relatively small domains of crystallinity. The bottom line is that glass, tempered or otherwise, basically doesn't change, on the order of centuries, if not millenia. It's no different than, say, Damascus steel, in retaining its mechanical properties. It's by far more robust than Teflon, which actually does flow under pressure.

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Without any equivocation, for once, one can actually state, "This is Trump's fault", as 555 California St. is owned in part by the Trump organization & Vornado Realty Trust.

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Without equivocation, that does make as much sense as some of the other stuff he is blamed for.

As a teenage summer job I worked for a glazing company. AC Yule in Aberdeen and its still quite surprising seeing jobs I worked on 35 years ago still looking good.

The safety glass you could throw bowling balls, hammers what you like at it in the scrap skip and they would just bounce out. If you wanted to break it to get more in the skip you just tapped the edge with a toffee hammer and the whole lot would go.

Its something to do with the result of the tempering process.

Glass does change over time, normal glass pre tempering you have about 1-2 years after manufacturing to cut it or form it. After that it gets much more brittle and unworkable in a cold state. If its been processed/treated it is of course unworkable.

A can't give a reference to it, its just experience.

Oh there is a rod of glass in either the science museum or one of the UK classical university's which is suspended horizontally between 2 supports which has a bit of a visual sag in the middle. Its 300-400 years old and the sag is mm over a 3ft length.

We had a lecture on glass in materials, from memory the modern stuff is completely different to the pre WW2 stuff which quite a lot of it is in modern standards higher than acceptable radioactive.

And to note there are glass instruments of the same era as the rod and there is no noticeable or measurable changes and they include optical glassware.

Not that it will be a factor in this case.

I suspect the window has flexed in its mount and moved over the years to get the edge into contact with something, maybe a screw head not put in flush, hard enough to trigger the self destruction mode of a side tap to the edge.

Glass is amazing stuff. We only got 1 lecture on it and the summary was its doesn't work the way you think it should, but its amazing stuff.

just some links. Annealed is the other state I forgot. If it has come down in larger panels it will be that instead of tempered. I think UK you have to use laminate safety glass above a certain height in building's to stop a shower of glass shards.

https://www.pilkington.com/en-gb/uk/architects/gla...

https://www.southampton.ac.uk/engineering/research...

If you look at the videos, it appears that the glass panels didn't disintegrate until they hit the ground. In the air, they were still large, single pieces of glass. And if you look in one shot, it showed a window with only a portion of the glass missing, like a chunk broke out, away from the rest of the window which was still in the frame.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

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It's finding someone you can't live without

that Pilkington link has the links to the UK codes on the subject I think.

UK though did change things after the PIRA bombing in London which basically blew out all the windows in the area.

I am no expert but if its big shards then it just annealed plain glass not tempered I think.

Tempered glass is usually only installed if there is significant risk of being hit, such as with floor level panes

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No clue all the stuff I was involved with was either double glazing units or Cordonas bowling alley in Aberdeen with single pane stuff and that we had great fun trying to break in the scrap skip until someone nearly got brained by a bowling ball lobbed off the roof and bouncing.

An interesting article about the type of glass used in modern high rise buildings. Heat strengthened glass seems to be the norm. I thought it clever that they include a few marked panels of tempered glass to allow firefighters to break in.

https://www.builderspace.com/what-kind-of-glass-is...

UK the firemen have a tungsten carbide tipped bolt gun that breaks them. Bit like the emergency hammers on trains but on steroids. They use it on car windows as well.

They press the front on which pushes back a safety interlock and they can release the spring.

I carry a tungsten-tipped tool in my car to break the windows. It also has a blade to cut your seat-belt. And yes, I keep it where I can reach it at any time. And there's a second one in my wife's car, also where it can be easily reached.

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Irvine, CA
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I've got one of those as well, but I don't think mine has tungsten tip, just steel.

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I suspect its to limit the follow through as the tip doesn't come out very far. And the glass basically drops vertically and you don't need to swing anything. They can also mount it on a suction cup holder and trigger it with a string.

You never want to be standing in front of any opening you just made whether it be a door or broken window during a fire. Any new opening introduces oxygen to the space and can cause a flashover.

Its all sensible stuff.

The old untreated glass does change, the reason I really don't know. I just know don't even attempt to cut it for a cheap fix for someone's green house. It just splits in funny directions never along the line.

They have loads of sheets of it around me of unknown age. I won't go near it. But you can see people sitting next to piles of broken glass trying to turn it into something. They spend 2-3 days messing around with it, when for 20 euro they could just email the local DIY shop with the sizes and pick it up the next day. And if you need to trim it then you can do. If the heavens align and you manage a straight cut with the old stuff and try and touch it again I have never yet seen it work.

You might wonder why I get involved in glazing. Basically its the kids playing and when something gets broken I really can't be bothered by the week of finger pointing and kangaroo courts trying to find out what happened. So I just get the size email the DIY shop stick the tools in the car pick it up and fit it without getting involved. And strangely there seems to be other fathers in the area that have learned this behaviour cuts out the ear ache and do it as well now. Seems to annoy some though as it removes the entertainment of a community kangaroo court.

So I can see windows lasting years through more severe weather then all of a sudden them breaking for apparently little reason if its cheap untreated glass.

555 California St. was built in 1969. No doubt it has been reglazed at least once and is probably due for another reglazing.

Quote (epoxybot)

Without any equivocation, for once, one can actually state, "This is Trump's fault", as 555 California St. is owned in part by the Trump organization & Vornado Realty Trust.

The problems are not isolated to Trump's tower.

https://www.ktvu.com/news/broken-glass-in-san-fran...

I believe there was at least one other highrise that lost panes.

The winds weren't that high, is it common for buildings in hurricane country to lose panes in 50-60mph winds? Maybe this is a government problem to have such a cluster of failures.

Article about highrise windows in hurricane country:

https://www.wlrn.org/news/2015-10-26/windows-lost-...


This winter has been quite something around here (SF Bay Area).

On the plus side, our California water resource people have been building many reservoirs over the last years, and all that extra water has been caught and stored for later drought. OOPS! No, sorry. That's an alternate reality.

Speaking of alternate reality: how about instead of the High Speed Train to Nowhere, that money had been spent on reservoirs? In THIS reality. Or maybe even (more) desalination.


spsalso

Quote:

Speaking of alternate reality: how about instead of the High Speed Train to Nowhere, that money had been spent on reservoirs?

That's easy, just monetize the water. Water rates are currently in the pennies per gallon range; amp that up to, say, $0.25/gal and people will stop using as much water, and there'll be more people interested in saving every drop of rainwater. If your water bill were $800/month, I think you'd even be interested lobbying anyone you can find to build more reservoirs and perhaps even build cisterns and roof-top/backyard rain catchers.

It's only about $10B, so the other choice is to raise taxes, either directly, or for the interest on the bonds required.

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Been doing a fair bit of research into glass on silicone glazing. Dow-Corning specializes in this. Some of their silicones are hurricane and explosion rated. My problem is that the windows were applied to the aluminum structure after it was painted. The bond between the paint and aluminum has failed. Haven't lost a window yet but they leak like heck.

Just buying windows for my workshop and this thread got me well clued up for the different options.

Al frames are a pain. And colossally thermally ineffective.

My max wind speed though is only 25 m/s

Whatever you charge for water, you can't sell it if you don't have it.


spsalso

Quote:

Whatever you charge for water, you can't sell it if you don't have it.

OK, so pay your extra taxes for the $10B

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Those reservoirs take money to build, as you know.

But without them, all that water that just went out into the ocean isn't going to be available for the next drought.

I would rather have built reservoirs than a high speed passenger line that whisks people from Merced to Fresno at a breakneck speed. At no small cost. When it's finally done.


spsalso

OK, you're volunteering to pay the $10B in taxes? Thanks for your generosity.

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"OK, you're volunteering to pay the $10B in taxes? Thanks for your generosity."

Well, if I can jack up the water prices like you're advocating ("...say, $0.25/gal..."), it DOES look like a really good investment (building new reservoirs).

What slows my admittedly un-financed enthusiasm is the thought that the Great State of California would decide I was being very bad, and "stat-ilize" my investment. I could be in error in predicting the actions of government entities, of course.


spsalso

San Francisco Building Department's response:


https://missionlocal.org/2023/04/broken-windows-th...


spsalso

Note that their facade program targets the oldest buildings buildings in SF yet all of the failures were on newer constructions.