Notre Dame

[Marland]

The thought of all that lead pollution is probably driving some greenies InSeine.

GH

[soup]

Well there is a bit of debate as to whether the vaulted stone ceiling was the actual structural member and the roof was just a timber covering clad in lead ( I had initially thought copper but lead makes much more sense). The way it has burned has rather agreed with the vaulted stone ceiling being the structural member and the wooden part just being a covering.

[soup]

A buttress is NOT half a bridge though so that's that theory F'ed.

[The Natural Philosopher]

it will be somewhat of both.

The stone vaulting would be much heavier, but wood and lead is not insignificant either.

The wooden roof is the rain cap. Its structural in the sense it holds iself up and eeds a stable base on which to rest. There probably are no full span cross members. So it will generate some lateral loads on te walls

[Harry Bloomfield]

Well then, you are wrong.

[Harry Bloomfield]

The Natural Philosopher formulated the question :

I am amazed at just how the managed to build the flying buttresses. I would imagine they tackled them as they would a stone arch bridge, building a wooden former to support the stone-work until completed, but with those weights at those heights?

[dennis]

The claim was that they were only erecting scaffolding so its a smoker or an electrical fault, probably.

Crushed fire alarm cable under a bit of scaffold?

[charles]

one suggestion was faulty lift motor - lift at the side of teh scaffolding.

[soup]

All (well all I have looked at) sources about the uses and physics of buttresses (flying or otherwise) 'talk' of them resisting outward bowing forces, not one of them 'talks' of these buttresses pushing inwards . Any way buttresses obviously don't push in or ND would have fallen down by now. And it hasn't, so somebody has something wrong somewhere.

[Chris Hogg]

Of course they push inwards. Action and reaction are equal and opposite. The outward bowing forces from the main structure of Notre Dame (or any buttressed building of that sort) are resisted and balanced by the inward forces from the buttresses. Take either away and what remains will collapse, either immediately or more gradually. The reason ND hasn't collapsed is because the bulk of the outward forces come from the heavy vaulted stone ceiling, which is intact for the most part. If that had gone, things might have been very different.

In the same way, one half of a bridge is balanced, i.e. buttressed, by the other. Take either away, and it collapses.

[Rob Morley]

Lean a stepladder against a partially open door and watch as it pushes the door away - that's how a buttress applies an inward force to a wall. The roof trusses are applying an outward force as they try to spread, and that's what the buttress is countering.

[harry]

Yes it is.

[harry]

For any structure in equilibrium, there are balanced/opposing forces. If they are unbalanced, it falls down.

Simples/elementary. Did you never go to school?

[mechanic]

There may be no beams as in a simple truss, which would take any sideways stress from the roof. The buttresses are an alternative to thicker walls, essential for the use of side aisles and to let light into the interior through large windows.

See 'Structures' by JR Gordon for simple explanation of how these things work.

[tony sayer]

In article <q99fmd$1j4$ [e-mail], Harry Bloomfield <harry.m1byt@N OSPAM.tiscali.co.uk> scribeth thus

Yes thats what they did, bit like Brunel building his Maidenhead railway arch bridge ...