post your pictures of bridges

Jonzjob wrote in post #19474226
How would you take the coefficient of expansion of the tape in to account in a belting hot boiler? If you used that method you'd probably find that the tape had expanded more than the boiler and then it would appear to shrink

Presumably any serious piece of measuring equipment would have a coefficient of expansion figure associated with it - even in the 1800s.

avondale87 wrote in post #19474230
They're both steel so expand the same

But wouldn’t the measuring tape be made of a flexible steel and the boiler made out of - - whatever - - having a different expansion coefficient? Dunno.

Ray.Petri wrote in post #19474235
Presumably any serious piece of measuring equipment would have a coefficient of expansion figure associated with it - even in the 1800s.

But wouldn’t the measuring tape be made of a flexible steel and the boiler made out of - - whatever - - having a different expansion coefficient? Dunno.

Not really
Steel expands 0.0011 mm per 100 metres per degree C.
The expansion would be negligible but measurable for something like a boiler say 1.2 metres diameter. Circumference 3.7 metres expands approx 0.4mm per degree C
Cast iron similar so unless the boiler made of lead or zinc,or gold which expands about 2.5 as much there'd not be a problem

I'd measure our bridges for expansion with a 1/16" steel band, applying a constant pull of 15 lbs (spring balance) and measured temperature.
If laying flat on beam then we'd sit the band and the thermometer on the bridge beam to equalise the temperature. Otherwise we'd be unsure of temperature of steel band.
Concrete expands similar but different to steel.
We'd let the engineers decide what expansion the concrete beams made.

avondale87 wrote in post #19474244
Not really
Steel expands 0.0011 mm per 100 metres per degree C.
The expansion would be negligible but measurable for something like a boiler say 1.2 metres diameter. Circumference 3.7 metres expands approx 0.4mm per degree C
Cast iron similar so unless the boiler made of lead or zinc,or gold which expands about 2.5 as much there'd not be a problem

I'd measure our bridges for expansion with a 1/16" steel band, applying a constant pull of 15 lbs (spring balance) and measured temperature.
If laying flat on beam then we'd sit the band and the thermometer on the bridge beam to equalise the temperature. Otherwise we'd be unsure of temperature of steel band.
Concrete expands similar but different to steel.
We'd let the engineers decide what expansion the concrete beams made.

You got it Richard. Now calculate the resonance of the bridge as per my previous post bottom of last page. just joking!

Ray.Petri wrote in post #19474213
Something I got involved in for a short time yonks ago - fortunately the project was abandoned due to more pressing problems.

However, Resonance - regarding bridges - is a vibration which can be destructive to the bridge - for example soldiers marching across the bridge will be ordered to ‘Break Step’ to prevent the possibility of the bridge resonating which could result in collapse.
A good example of this can be seen in the link below for the Millennium Bridge in London.

https://en.m.wikipedia​.org …um_Bridge,_Lond​on#/search

Don't forget the Tacoma Narrows Bridge
https://www.youtube.co​m/watch?v=j-zczJXSxnw

I think they still use this video to show real examples of resonance and standing waves in schools.

Ray.Petri wrote in post #19474186
Thank you, Richard.

And just how did you remember that explanation Capn’. Very amusing!


Thanks for the comments and info everyone .

Calvin & Hobbs was once an extremely popular comic in the USA. The author stopped before it got stale. Many of the comics became well remembered or turned into memes. A cotemporary comic that also is oft reposted is "The Far Side".

Capn Jack wrote in post #19474495
Don't forget the Tacoma Narrows Bridge
https://www.youtube.co​m/watch?v=j-zczJXSxnw

I think they still use this video to show real examples of resonance and standing waves in schools.

Thanks Capn. I have seen that video on the box - maybe, just maybe if the bridge had been terminated in it’s characteristic impedance - or whatever the mechanical term is - it’d have been ok. I wonder who picked up the tab for that one?

Capn Jack wrote in post #19474495
Don't forget the Tacoma Narrows Bridge
https://www.youtube.co​m/watch?v=j-zczJXSxnw

I think they still use this video to show real examples of resonance and standing waves in schools.

That is horrendous.
Amazing filming.
Thanks for posting. Terrible as it was it's interesting

That reminds me of the Millennium Bridge across the Thames. That bounced quite well too

https://www.youtube.co​m/watch?v=y2FaOJxWqLE

Still, I expect that the 'designer' still kept his cash!

Pass over the Swartberg, build in 1888 to link the Little Karoo with the Great Karoo.
Edit: I realized too late that I posted this in the wrong thread! It was meant to be a "Road photo"
Another edit: I decided to move the images

Sligachan Old Bridge, Isle of Skye.

IMAGE LINK: https://flic.kr/p/2odX​xHa

SJA wrote in post #19475840
Sligachan Old Bridge, Isle of Skye.

IMAGE LINK: https://flic.kr/p/2odX​xHa Scotland 2023 by Sabrina Aspinall, on Flickr

It is a nice composition because the background hills follow the shape of the bridge.

That's a lovely view of the Cuillin Mountains and Sligachan bridge.

The locals say that if you can't see the Cullins then it's raining and if you can then it's going to rain! It's other name is the Misty Isle.It didn't rain the number of times I had holidays up there so I guess that the sun shines on the righteous A beautiful island!

The Cullins are quite often used as a practice for climbers who atre going on to the Alps. I wanted to have a walk over them but I was told that it would have been far too dangerous unless I was an experienced cimber, which I ain't so I didn't

The Millennium Bridge, officially known as the London Millennium Footbridge, is a steel suspension bridge for pedestrians crossing the River Thames in London, linking Bankside with the City of London.

This picture is taken from viewing gallery at Tata Modern.

IMAGE LINK: https://www.fantasticp​ix.co.uk …on-England-UK/i-h8Ffzvc/A

Five London Bridges - From the top of the Shard 306m high.
It was a very misty rainy day in November when I took this shot and the internal reflection from the windows presented a problem - hence the lines running across the river.

The bridges are - from nearest to Farthest (Right to Left)
1. London Bridge.
2. Cannon Street Rail Bridge.
3. Southwark Bridge.
4. Millennium Bridge.
5. Blackfriars Rail Bridge.