Author Topic: Berlin AquaDom explosion - what went wrong?  (Read 12326 times)

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Offline pcprogrammer

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #25 on: December 17, 2022, 11:43:29 am »
I'm also surprised we don't see much of the central tube remaining, as I would have thought that would be safe from a failure of the outer walls.  Imagine if someone had been in that elevator shaft when the main tank burst.  That could have been deadly.

Or what about a diver in the tank doing maintenance or the fish feeding.

Online Ian.M

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #26 on: December 17, 2022, 11:51:16 am »
All the shots I've seen so far show the inner tube is still intact.  However its probably compromised as its most likely been exposed to the same chemicals the outer shell, and experienced the rapid removal of the inwards stress and a transient outwards pressure differential of up to one atmosphere over much of its length as the water fell out.

Got any photos (or video + timestamp) showing significant damage to the inner tube? 
 

Offline AndyBeez

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #27 on: December 17, 2022, 12:15:42 pm »
The sheets were bonded in 2003. Did they ultrasound the material and the bond lines for micro fractures - as you need to do on an aircraft wing/body?

So does anyone have access to a mechanical stress simulation package? Would be interesting to calculate the loading at the base of the inner and outer cyclinders; especially as they held 1000 tonne of water. The surface loading at the base would have been similar to that experienced by a nuclear submarine or an orbiting space capsule. And we don't make those from plexiglass. Other factors to model; temperature cycling, vibration from the lift, air pressure on the top surface... even ultraviolet and chemical ageing of the material.

An fine example of, if engineers can, then maybe they shouldn't. Fail. :palm:

 

Online tom66Topic starter

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #28 on: December 17, 2022, 12:26:36 pm »
You can see parts of the inner tube failed here, at least it appears to be part of that area:



I'm not sure how much of the tube is damaged.  It could have occurred post-collapse when the rest of the structure fell in towards it, perhaps.
 

Offline tooki

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #29 on: December 17, 2022, 12:51:51 pm »
I saw one interviewee on a German news segment who suspected it was not fatigue, but mechanical damage. I assume the German authorities, the tank manufacturer, and all the involved insurance companies will be performing extensive analysis on the failure, so I expect we will eventually find out exactly what went wrong.
 
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Online Ian.M

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #30 on: December 17, 2022, 12:54:29 pm »
@Tom66,
The area below the aquarium base was a bar + access to the elevator.  I don't believe the inner tube extended below the concrete aquarium base.  However I think there were curved glazing panels above the bar to give the appearance it did.   

I agree that looks like a crack in the inner cylinder (right photo behind shard of outer shell).  I did say "probably compromised" . . .    IMHO the whole inner cylinder is scrap as its probably crazed with micro-cracks, and even if it isn't, the general public would never trust it unless it was completely replaced.

@AndyBeez,
The hoop stresses are easily calculable (without stress simulation software) if you take the known tank dimensions, and scale off them for the water level.  However without knowing the details of the shell and inner cylinder to base joints, and also whether or not any of the weight of the two cylinders was supported from the top, its impossible to calculate the stresses there.

Wikipedia claims the water column was 14 m.  That's only about 1.4 atmospheres pressure, or about 5% of the typical operating depth for a nuclear submarine in deep water.   It is 40% more than the internal atmosphere pressure the ISS runs at.  However neither application requires a transparent hull so comparison with them is totally irrelevant except to get a 'human scale' feel for the forces involved.
« Last Edit: December 18, 2022, 07:27:56 am by Ian.M »
 

Offline MrMobodies

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #31 on: December 17, 2022, 07:57:06 pm »
According to this article there was there a power cut before the explosion.

https://www.bbc.co.uk/news/world-europe-64010677
Quote
Hundreds more fish that were kept in the basement for breeding purposes were also at risk from the power cut that followed the incident but they have also now been moved to safety.

I wonder could that be a contributing factor?

I mean if there was any power used to maintain a set water temperature.

The bonding is claimed to be proprietary, but it's a reasonable guess that it's a case of polishing the mating surfaces and then using an adhesive of some kind, there are only so many ways to solve this problem. I wonder if it is possible that at the surface exposed to the water that adhesive could progressively allow water into the joint, which eventually forced two halves apart, especially if the low temperatures of the hotel lobby allowed for some kind of expansion-contraction against the 26C tank water.   

The problem with this explanation is this might lead to the tank bursting,

https://abcnews.go.com/International/wireStory/huge-berlin-aquarium-bursts-housed-1500-tropical-fish-95405351

Quote
There was speculation freezing temperatures that got down to minus 10 degrees Celsius (14 degrees Fahrenheit) overnight caused a crack in the acrylic glass tank, which then exploded under the weight of the water. Police said they found no evidence of a malicious act.

So it was -10c before the explosion but that is speculation.
« Last Edit: December 17, 2022, 08:16:24 pm by MrMobodies »
 

Online langwadt

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #32 on: December 17, 2022, 08:31:10 pm »
According to this article there was there a power cut before the explosion.

https://www.bbc.co.uk/news/world-europe-64010677
Quote
Hundreds more fish that were kept in the basement for breeding purposes were also at risk from the power cut that followed the incident but they have also now been moved to safety.

I wonder could that be a contributing factor?


how do you interpret "followed the incident" as being before it happened?

if you spill 1 million liter of saltwater, you are probably going to lose power ...

 
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Offline ebastler

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #33 on: December 17, 2022, 08:44:21 pm »
Quote
There was speculation freezing temperatures that got down to minus 10 degrees Celsius (14 degrees Fahrenheit) overnight caused a crack in the acrylic glass tank, which then exploded under the weight of the water. Police said they found no evidence of a malicious act.

So it was -10c before the explosion but that is speculation.

The aquarium tank was located in a hotel lobby, i.e. a well-heated, temperature-controlled environment. And any source which uses the word "exploded" in this context can't be trusted with their speculation anyway.

(Edit: typos...)
« Last Edit: December 17, 2022, 09:12:13 pm by ebastler »
 
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Offline MrMobodies

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #34 on: December 17, 2022, 08:49:48 pm »
how do you interpret "followed the incident" as being before it happened?

* if you spill 1 million liter of saltwater, you are probably going to lose power ...

I interpret the power cut before the explosion happened.

For you to ask obviously my interpretation is wrong.

* Aaah I see, the flood caused the powercut.

Sorry about that.
« Last Edit: December 17, 2022, 08:51:34 pm by MrMobodies »
 

Online tom66Topic starter

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #35 on: December 18, 2022, 12:04:41 am »
So it was -10c before the explosion but that is speculation.

This is speculation I think which originated from the police, but I am sure the lobby area was heated somewhat; to not do so would be greatly uncomfortable for anyone walking through.  However, it *is* conceivable, due to the current price of energy, that the heating was reduced.  So perhaps instead of 20C, with a 6C delta between the inside and outside, maybe the lobby was kept around 15C, and maybe colder overnight?  I am not sure what the law is in Germany, but there was something about public buildings being restricted for heating in winter due to gas shortages, maybe this applied to hotels too? 
 
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Offline Infraviolet

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #36 on: December 18, 2022, 12:33:09 am »
Does anyone know if any footage of the moment of the burst was captured? I heard it happened in the early morning hours, but was there CCTV? if there is it might be very revealing as to how the burst happened, also it would be facinating to truly see what the event looked like as it happened.
 

Online tom66Topic starter

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #37 on: December 18, 2022, 12:36:49 am »
There is probably at least some CCTV, and assuming the DVR wasn't sitting right under the million litres of salt water, that footage will be analysed to see what happened.  Whether it was pointing at the tank was another matter, it seems unlikely you'd need to film that unless you were expecting catastrophic failure.  I think it's unlikely that such footage gets released unless the German state decides to conduct whatever their equivalent of a public enquiry is, given it's not a public building and no one is dead there is probably no scope for that.  It is probably a matter for the insurers and lawyers at this point, so unless someone leaks the footage we'll just have what their report says (or maybe the Reynolds company or another construction firm will end up in court - if so it's likely the footage would make an appearance.)
 

Offline AndyBeez

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #38 on: December 18, 2022, 12:56:12 am »
Wikipedia claims the water column was 14 m.  That's only about 1.4 atmospheres pressure
In fresh water the depth pressure at 14 meters is 19.85 psi, but in salt water this rises to 20.38psi. The added 0.53 psi equates to an extra 35cm in depth. A million litres of salt water weighs in at 1,023 tonne, 26 tonne more than the 997 tonne for just fresh water.

 

Online Ian.M

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #39 on: December 18, 2022, 01:18:06 am »
Yes, and the density also varies with temperature, but the difference is even smaller.  It really doesn't matter as we don't know the fill depth accurately enough for a density difference of under 3% between fresh and sea water to be significant.
 

Offline AndyBeez

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #40 on: December 18, 2022, 01:37:54 am »
As long as they did their sums using salzwasser  ;)
 

Offline pcprogrammer

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #41 on: December 18, 2022, 06:33:48 am »
My money is on the millions of kids who have passed through there putting chewing gum on the outside of the tank over the years. Also age as someone else put it.

The outside of the tank was over 8 meters of of the lobby floor, so no passing by to stick anything to it.

Offline pcprogrammer

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #42 on: December 18, 2022, 07:06:45 am »
True, but I doubt it to be fully open. To much of a liability on someone getting hurt. And then still the inner tube may have survived and not have been the cause of the whole ordeal.

Online tom66Topic starter

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #43 on: December 18, 2022, 08:42:30 am »
If the inner tube broke first, the failure would have been to flood the lobby and lift with water and fish, but the tank itself would still look relatively intact.   Instead, it looks like the outer wall failed first, and in the collapse, it may have damaged parts of the inner tube.
 

Offline ebastler

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #44 on: December 18, 2022, 09:03:46 am »
So it was -10c before the explosion but that is speculation.

This is speculation I think which originated from the police, but I am sure the lobby area was heated somewhat; to not do so would be greatly uncomfortable for anyone walking through.  However, it *is* conceivable, due to the current price of energy, that the heating was reduced.  So perhaps instead of 20C, with a 6C delta between the inside and outside, maybe the lobby was kept around 15C, and maybe colder overnight?  I am not sure what the law is in Germany, but there was something about public buildings being restricted for heating in winter due to gas shortages, maybe this applied to hotels too? 

More speculation. There was a large bar and café in that lobby, right beneath the aquarium. People were meant to sit there, eat and drink and be comfortable. Rest assured that it was not at 15°C.

What about the elevator that goes down in the middle. I suppose it depends on the elevator but if there isn't any doors.

Sheesh, of course the elevator cabin was fully enclosed, by transparent walls which were part of the moving cabin. You could, like, squeeze your fingers otherwise.  :palm:

The level of uninformed speculation in this thread is particularly bad. Why not use at least the publicly available information?
 

Offline Barny

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #45 on: December 18, 2022, 11:02:11 am »
My guess is that some cleaning company used an alcohol based cleaning agent.
Or some diligent person desinfected EVERY surface.

The fumes of disinfectant could also added to the disaster to.
 

Offline AndyBeez

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #46 on: December 18, 2022, 11:16:14 am »
One assumption is the aquarium burst at the bottom of the tank. The break may have been higher up, causing the acrylic to unzip in a catastrophic failure. The 'nitch' that broke it may even have been on the very top edge. Going unnoticed for days/weeks, the near invisible crack propogated slowly downwards, until reaching the depth where load exceeded strength.

Only the fish know the truth, and they ain't here to talk :-X
 

Offline amyk

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #47 on: December 19, 2022, 12:40:19 am »
So it was -10c before the explosion but that is speculation.

This is speculation I think which originated from the police, but I am sure the lobby area was heated somewhat; to not do so would be greatly uncomfortable for anyone walking through.  However, it *is* conceivable, due to the current price of energy, that the heating was reduced.  So perhaps instead of 20C, with a 6C delta between the inside and outside, maybe the lobby was kept around 15C, and maybe colder overnight?  I am not sure what the law is in Germany, but there was something about public buildings being restricted for heating in winter due to gas shortages, maybe this applied to hotels too? 

More speculation. There was a large bar and café in that lobby, right beneath the aquarium. People were meant to sit there, eat and drink and be comfortable. Rest assured that it was not at 15°C.
I think what he's saying is that they could've adjusted the thermostats to a lower setpoint during the night in order to save heating costs when there might not be people in the lobby, leading to more thermal cycling.
 
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Offline EEVblog

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #48 on: December 19, 2022, 02:40:05 am »
 
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Online SiliconWizard

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Re: Berlin AquaDom explosion - what went wrong?
« Reply #49 on: December 19, 2022, 03:36:16 am »
This is a fish genocide.
 


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