Question Power station chimneys demolished.

[Notebook]

The chimneys, which had stood tall for 40 years, came down in seconds.

Nothing special about this, just old structure being demolished.
However, I notice both chimneys start to come apart at the same physical place. About 5secs in for the left chimney.

Just curious, would these(or any) chimneys have been built as circular cross-section, then conical to the top?

I could wiki of course, but usually some one here has an answer, or a different aspect.

http://www.bbc.co.uk/news/av/uk-england-essex-41427239/tilbury-power-station-chimneys-demolished

N.

 

[RisingFury]

Don't know the answer to your question, but I love the wind turbine in the back of one of the shots.

 

[Urwumpe]

However, I notice both chimneys start to come apart at the same physical place. About 5secs in for the left chimney.

A bit of explosives can be helpful there....

 

[Notebook]

I did wonder about that, can't tell from the audio if the break-up of the first chimney is caused by a second explosive, or the detonation of the second chimney.

Its always fascinated me how brick chimneys can keep intact so long.
Would have thought the side in tension as it topples over, would fragment? Guess its the mortar keeping the individual bricks together?

N.

 

[Urwumpe]

Would have thought the side in tension as it topples over, would fragment? Guess its the mortar keeping the individual bricks together?

Depends on the way the chimney had been constructed. Generally, they include secondary explosives for such tall buildings because otherwise the top would get too much horizontal velocity and debris would fly far away. I remember some demolitions, where they carefully folded the chimney two-three times to make sure it falls almost vertically into a heap of sand.

 

[Notebook]

As far as I know, bricks are good in compression, weak in tension? Would assume they aren't a simple tube, and have various reinforcement parts inside?

If there is a second charge about a third of the way up, how is it detonated? Timer from the first charge or remotely from a box?
And why do I keep asking all these questions?

N.

 

[Urwumpe]

Timer from the first charge

Delay lines from the primary fuze, at least in Germany because the laws on explosives are pretty strict here. But I doubt they would risk having a second trigger somewhere else.

Its like in mining a tunnel, the spider web-like layout of the lines to the explosives determines the timing of each explosion, by having lines of different length to each circle of explosives.

I am more concerned: Why do I know about this stuff?

 

[C3PO]

I guess gravity takes care of most of the tensile forces.

 

[Urwumpe]

As far as I know, bricks are good in compression, weak in tension? Would assume they aren't a simple tube, and have various reinforcement parts inside?.

And that depends - there are brick chimneys which are simply held together by mortar and gravity. And there are those long slender reinforced, pretensioned concrete chimneys, which a giant combat robot could use as baseball bat.

 

[Notebook]

Fascinating things chimneys, they look simple, but not.

This chap got a telly series out of them:

You might not get away with that these days...

N.

 

[MaverickSawyer]

Definitely a second set of charges. The dust plume from the break point was too neat and uniform to be a random failure at that particular point.

 

[Andy44]

And why do I keep asking all these questions?

N.

Because you're an orbinaut, someone who is curious about the world and how it all works.

 

[JMW]

Tell you what, you've gotta have confidence in the guys that do that to be anywhere near ! :facepalm:

Fred Dibnah was a real character !

 

[Notebook]

He was, died a few years ago I think. His early stuff was best, going up a chimney with just a wooden ladder. Then dismantling it brick by brick. Scary just watching.

[ame="https://www.youtube.com/watch?v=3R3-YwDZrzg"]Fred Dibnah How to climb a chimney overhang at 50+ - YouTube[/ame]

N.

 

[Artlav]

Does not look like secondary explosions to me - the chimneys can't rotate as fast as they want to fall, so at that point the side-force of gravity is pretty high, and most buildings don't have much of a side-load strength.

You can see in the side shots how the top starts falling straight down much faster once it folds, rather than keeping up with the base.

There is also a lack of a report at the right time, and the fact that it seem to start folding before the smoke appears.

 

[Andy44]

In many places in the US, those old chimneys would be kept around and new chic apartment building would be built around them so yuppies and hipsters could feel like they were in an industrial area while living super comfy post-industrial lifestyles lol/

Like here, in Georgetown, Washington, DC along the old C&O Canal. This was once a filthy, stinking tannery district, now it is a hilariously expensive area to live in along the Potomac River. Note the tall, no longer functional smoke stack in the background:

 

[Notebook]

UK yuppies wouldn't know what a chimney is for, and as for a gasometer...

http://www.bbc.co.uk/news/magazine-30405066

 

[Andy44]

UK yuppies wouldn't know what a chimney is for, and as for a gasometer...

http://www.bbc.co.uk/news/magazine-30405066

That reminds me of the vast numbers of old steel girder bridges that used to be found in every town in western Pennsylvania and other rust belt towns when I was growing up. Those bridges were often painted a colorful green (roads) or black (railroads) and they were everywhere. They gave those little industrial towns in the valleys their character.

While there are still quite a few, they are being replaced by modern flat concrete highway bridges as they age out. Just not the same.

 

[Notebook]

Just curious. was Town Gas(coal gas) common in US cities? I imagine it would be in Europe, common development.

N.

 

[Andy44]

Just curious. was Town Gas(coal gas) common in US cities? I imagine it would be in Europe, common development.

N.

Maybe once it was, but I have never heard of it. I don't recall seeing gasometers like you see in the UK, anyway. The US has lots of oil fields, and where there is oil there is usually natural gas, which I think is most common here.