Hot Buildings and expansion.

I have just seen a report that shows that some steel structures i.e. buildings and bridges are growing by more than the designed expansion in the temperatures we have recently had. There is a bridge in London which is closed because of structural damage caused by expansion. Can the cladding fall from tall buildings if they grow to much?

David

The interior lining of a BAC 1-11 for Aloha airways fell from the ceiling when the fuselage grew longer and faster than the cooler inside furnishings !

I think you may mean Hammersmith bridge which is closed to all traffic including pedestrians both on and below it plus all river traffic. The suspension link eyes are showing extensive cracking and I believe the towers are also showing signs of cracking !

I suppose tall buildings would expand more on the sunny side than the "cold" side giving a banana effect.

The Tinsley viaduct in Sheffield has a series of steel link Bridge plates to allow for expansion and contraction over the year.

One end is anchored securely and the other sits on bearings to allow it to move.

I think it stretches by a couple of feet

Used to watch the huge dips in rail side telegraph cables when travelling to the seaside in summer, then marvel at how taught they became in winter.

I read somewhere that Concord didn't have properly fitted carpets because it grew so much in flight and the Lockheed SR71 Blackbird leaked fuel like a seive on the ground but was fine when flying supersonic.

Not to mention the allowances for shrinkage of castings that our forefathers had to factor in when making patterns.

Ain't temperature great....

We had a robot mounted on a framework suspended from the roof steelwork, it applied adhesive to a panel in a jig on the floor. Mysteriously the adhesive path was moving when the weather was hot, the robot task program was contained in a frame so a hot weather offset could be applied to correct the path, it was a bit of a puzzle until the correlation to the weather was noticed.

Mike

Plasma,
I don't dispute your Blackbird story but how do you decide whats leaked away and whats burnt when you're doing Mach 2?.

Pattern makers still have separate rulers with allowances to suit the metal being cast. Chesterman Rabone offer a set of 4, one standard and three to suit Iron, steel and brass. (aluminium alloy is generally the same as brass). Trouble is there are far fewer local foundries than in our forefather's days so you don't see many of them nowadays. You got to go East to find them today.

Mike,
Not only temperature has a potential impact on machines. My head scratcher was a multi head driller that misaligned with the seasons and that arose from the building having been built with one corner on a wet clay bed that expanded in the wet winter months and induced a twist into the suspended first floor where the machine was sited and then shrank through the summer months. Pneumatic isolation mounts with just three reference points sorted it out but the machine did lean a bit in the winter!!
But the holes were in the right place.

I wonder where the assumption that bridges last forever comes from? I can't think of any other pieces of machinery that are expected to still function as new after 100-plus years of continuous service. Especially ones that lives depend on. Massive pillars of stone etc that the Victorians built with thousands of cars and even trains still driving over top of them every day. Pretty scary when you think about it really.

'I read somewhere that Concord didn't have properly fitted carpets because it grew so much in flight and the Lockheed SR71 Blackbird leaked fuel like a seive on the ground but was fine when flying supersonic.'

I read somewhere that on the final flights of the BA Concordes that the flight crew jammed their caps in the gap between the cockpit bulkhead and the Flight Engineers panel,which closed up by contraction on landing, the only way to get them out easily was to fly at Mach 2 again...........

The SR71 leaked fuel on the ground and climbout, but sealed up before it got to high mach speeds, the crew used astronaut style food in toothpaste type tubes, they would place these against the cockpit windscreen framing to warm it up!!

Cheers, Pete

Edited By Morty on 15/08/2020 23:54:07