Fire in Notre Dame in Paris

[zapatos]

2 hours ago, dimreepr said:

Laminate beams seem a reasonable compromise. 

[dimreepr]

2 minutes ago, zapatos said:

And they could be made to look like the original. 

[Carrock]

Enthalpy, you seem to be refuting things I didn't write, partly by agreeing with things I did...

 

2 hours ago, Enthalpy said:

With metal beams, there would have been even less fire damage.

I ignore why the spires were not built. The towers are obviously meant to carry much more weight - just observe the sections up to the present top. The spires were in the plans in 1160 but abandoned in 1240, I haven't read a reason. With present materials, they would weigh a fraction of what was possible then.

As spires are a relatively low part of the total cost, it's a reasonable speculation that the materials, build quality or foundations were considered inadequate for the extra weight.

5 hours ago, Carrock said:

Very old buildings still in use often are and sometimes have to be somewhat modified over the years, but the default assumption should be that as they still exist the builders were competent.

Thanks for the expansion...

 

2 hours ago, Enthalpy said:

The very Notre-Dame shows that builders do how they are used to within their time. The construction spanned two centuries (if you allege it's finished without the missing spires) and the style is hybrid, the techniques too. Most other constructions had their plans heavily modified over time, before or after "completion". Check for instance the Stephansdom in Vienna, St Vitus in Prague... about every cathedral

Construction of Notre-Dame (English)
Construction of Notre-Dame (French, other details)
Stephansdom
Saint Vitus in Prague
In Notre-Dame, the transept was added later and their front increased even later, and so on and so forth.

 

2 hours ago, Enthalpy said:

Don't overestimate neither the knowledge of middle-age architects. Many of their buildings collapsed, others (cathedral in Strasbourg and more) could not be finished because their design was flawed. That some buildings still stand is an achievement, but don't presume present architects would do it worse. Many Parisian buildings date back to 1850-1870

You seem to be suggesting nothing was learned from those failures and the builders of Notre Dame etc were just lucky. Really?

When I referred to builders' competence I was referring to collective competence. This would include judgment of whether many nonstandard constructions were adequate. I still believe modern architects would not do as well as the builders unless you allowed them to use some modern technology e.g. pencil and paper.

 

I didn't mention architects as they were as rare as hens' teeth...

From https://en.wikipedia.org/wiki/Architect

Quote

Throughout ancient and medieval history, most of the architectural design and construction was carried out by artisans—such as stone masons and carpenters, rising to the role of master builder. Until modern times, there was no clear distinction between architect and engineer.

...

Paper was not used in Europe for drawing until the 15th century but became increasingly available after 1500.

 

13 hours ago, Enthalpy said:

My proposal for a new roof: aluminium tiles.

Gotta wonder if the next fire will be hot enough to ignite aluminium...

[dimreepr]

5 minutes ago, Carrock said:

When I referred to builders' competence I was referring to collective competence. This would include judgment of whether many nonstandard constructions were adequate. I still believe modern architects would not do as well as the builders unless you allowed them to use some modern technology e.g. pencil and paper

That's a consequence of evolution rather than intelligence... 

5 minutes ago, Carrock said:

When I referred to builders' competence I was referring to collective competence. This would include judgment of whether many nonstandard constructions were adequate. I still believe modern architects would not do as well as the builders unless you allowed them to use some modern technology e.g. pencil and paper

That's a consequence of evolution rather than intelligence... 

[Carrock]

17 minutes ago, dimreepr said:

That's a consequence of evolution rather than intelligence... 

That's a consequence of evolution rather than intelligence... 

Not that each has competence in different activities?!

Or am I insufficiently evolved to appreciate your joke!?

[dimreepr]

1 minute ago, Carrock said:

Not that each has competence in different activities?!

Or am I insufficiently evolved to appreciate your joke!?

What joke?

[Carrock]

5 minutes ago, dimreepr said:

What joke?

Good to know there wasn't one.

Edited April 29, 2019 by Carrock

[dimreepr]

20 minutes ago, Carrock said:

Good to know there wasn't one.

I didn't say that...

[John Cuthber]

8 hours ago, Enthalpy said:

The Church seems richer in Britain.

It's the same church.

8 hours ago, Enthalpy said:

It does make an economic difference whether visitors can come in 2 years or in 15 years.

 

13 hours ago, John Cuthber said:

There is no need for everything to be "modern"  profitable.

 

[Enthalpy]

8 hours ago, Carrock said:

As spires are a relatively low part of the total cost, it's a reasonable speculation that the materials, build quality or foundations were considered inadequate for the extra weight.

This is only a speculation. While other cathedrals did break as spires were built, Notre-Dame looks sound. No visible deformation. The towers are built sturdy up to their top, obviously to support more weight.

There can be completely different reasons. Maybe a king was eager to inaugurate and use the cathedral, rather than continue the work and wait 30 years more for his successor to do it. Or some crusade had exhausted the economic and human potential of the country - this is more than a hypothesis: the towers' construction was stopped just before the 7^th crusade
https://en.wikipedia.org/wiki/Crusades

Anyway, we can build the spires now at a fraction of the weight then.

8 hours ago, Carrock said:

I still believe modern architects would not do as well as the builders unless you allowed them to use some modern technology e.g. pencil and paper.

That's clear to me too. That way of working is lost and won't come back. Just like many construction techniques are lost: archaeologists observe old buildings and try to deduce what the techniques were, but this suffices to publish a research paper, not to build now with the techniques of then.

So I don't consider a second asking present architects to design a building without modern tools. They shall exploit what's available. Think at the analysis of soils for instance, it gives a huge advantage. Or the understanding of lightning impact. And, why not, CAD and finite elements.

So I do claim that present architects can plan the (re-) construction of a cathedral better than people in the middle-age - not because they would be more clever now, but just because Mankind has accumulated better techniques.

For Notre-Dame's roof, we are lucky enough that we still build roof structures out of wood beams, so it remains an option.

3 hours ago, John Cuthber said:

There is no need for everything to be "modern"  profitable.

And my next sentence began with "More importantly".

But, yes, tourism matters a lot to France: it's one of its biggest income sources, together with agriculture, like for other under-developing countries. This fire is a blow to the French economy easily as big as the 737 Max problems is to the US economy.

11 hours ago, dimreepr said:

Laminate beams seem a reasonable compromise. 

I like this option. But I have interrogations.

How long do laminates last? I understand they rely on glue, which I mistrust on the long time. I wouldn't even use a synthetic polymer if it's for a millennium.

That won't be the same construction as the original. The roof structure isn't visible neither. So why not go directly to reliable materials, that is, metal?

Metals creep very little and are very little subject to fatigue. These behaviours are even predictable. They expand zero with humidity and little with heat, in a predictable manner. To add a roof over high thin walls of undocumented and old stone construction, I prefer to fully trust at least the roof materials.

Edited April 29, 2019 by Enthalpy

[John Cuthber]

And, obviously, no tourist would go to a building that was  in poor repair

https://en.wikipedia.org/wiki/Stonehenge
(That's the UK's most visited tourist attraction)

or to a cathedral that was undergoing building work.

https://en.wikipedia.org/wiki/Sagrada_Família

(That's Spain's 2nd most popular tourist attraction)

20 hours ago, Enthalpy said:

How long do laminates last? I understand they rely on glue, which I mistrust on the long time.

Timber is a composite material. The last lot lasted 800 years.

Glued timber is known to last a long time

https://www.cmuse.org/the-oldest-surviving-violin-who-made-it/

https://museumcollections.rcm.ac.uk/rcm_collections/guitar-belchior-dias-lisbon-1581/
And, as you have pointed out, they only have to make do with glued timber for a few decades while the oaks grow.

 

[Enthalpy]

Here's an example of a roof frame made of aluminium beams. Sections and lone beams shall be welded, cleaned and anodized at the workshop, transported by boat, lorry or other (even helicopter), assembled at the cathedral, on top of the walls or maybe on the ground.

The idealized roof comprises 19 sections as sketched, but no transept nor conical end that need better drafting tools. The sections are 5.72m apart, with lengthwise beams at each node, plus diagonal beams where signalled.

Assembly could be done with:

• Titanium bolts. Taylor making is cheap. No strong alloy is needed, so favour the corrosion resistance. A believe the bolts need no pre-stress here, which eases galling.
• AA5754 or AA5083 aluminium rivets maybe (not AlCu4Mg!); anodizing is lost at the holes, but rivets use to be watertight, and the created heads can be anodized at the site.
• Or break the anodizing where needed, weld at the site, anodize the seams at the site: good with AA5083.
• For assembly by wedges, ask a woodworker.

If oxide densification isn't yet done in the wild, invent the machine.

I still apply 100% of 2.2kPa = rho*V²/2 for 60m/s gusts on the whole surfaces. The 5.65m beams under the tiles experience then 50kN*m bending, which loads the 300*150*15 section of AA5083 to 110MPa/2.

All tensile and compressive loads, under 100kN, are much smaller than the beams' yield and buckling limits. I take a 150*150*10 section for the other beams to ease their assembly with the flexural ones, no excellent reason. The structure weighs then some 40t, with the tiles 80t for the idealized roof.

The design is quite suboptimum, with loads so small. A frame with shorter and more abundant beams would be even lighter. But why?

• The longest lone beam, 8.5m, fits in a lorry. Taylor extrusion isn't limited to 6m.
• 300*150 is already big for an extrusion. The profile can be bent and welded from sheet, but long seams have a cost. Possible argument.
• A 120t roof including the transept costs less than 1M€ aluminium. Assembly must cost more, and more elements worsen it.
• Thicker aluminium resists corrosion longer if the anodizing is lost. Failures happen at the ends.
• I ignore what load directions the stone walls accept. If pulling upwards is impossible, the roof needs a minimum weight: 220t estimated with huge margins, and then dry sand would compensate any saved aluminium: I prefer thicker metal then.

The roof could be much stronger than this already excessive design, more so with titanium. It could then hold only between the towers and at the transept, to inject no wind load at the walls. It could even hold the walls laterally if desired.

Marc Schaefer, aka Enthalpy

On 4/30/2019 at 8:48 PM, John Cuthber said:

Glued timber is known to last a long time
https://www.cmuse.org/the-oldest-surviving-violin-who-made-it/
https://museumcollections.rcm.ac.uk/rcm_collections/guitar-belchior-dias-lisbon-1581/

Bowed instruments design minimizes the stress at the seams, and failure isn't deadly. I've already seen and heard how easily the fragile hide glue breaks under the luthier's tools, and I wouldn't put unknown people under a roof glued like that. You may also notice that instruments are kept in a protective micro-climate.

By the way, nearly no old bowed instrument has still its original glue seams. Most instruments were modified during the romantic period, which implied to open the soundbox. More reasons let open the soundbox several times in a century, a routine operation - including when the glue seam breaks, which can happen over time.

[John Cuthber]

It's fairly clear that we could rebuild NDdP from aluminium and titanium.

The question is why would we want to?

Shouldn't we restore it as well as we can, and build new buildings in a modern style?

[Enthalpy]

Lead from the roof shouldn't be discarded as ordinary toxic waste. It's precious for science, as a shield material against ionizing rays.

Freshly mined lead contains radioactive nuclides (elements and I suppose lead isotopes) from the parent nuclides that decayed into lead. They create background noise in the rays detectors. In old lead, most unstable nuclides have already disappeared.

Some experiments used lead from sunken antique boats. Several 100t of Pb, 800 years old, is a fabulous asset for science.

[dimreepr]

2 minutes ago, Enthalpy said:

Lead from the roof shouldn't be discarded as ordinary toxic waste. It's precious for science, as a shield material against ionizing rays.

Freshly mined lead contains radioactive nuclides (elements and I suppose lead isotopes) from the parent nuclides that decayed into lead. They create background noise in the rays detectors. In old lead, most unstable nuclides have already disappeared.

Some experiments used lead from sunken antique boats. Several 100t of Pb, 800 years old, is a fabulous asset for science.

What's your point?

[Enthalpy]

Keep this lead preciously for science! More useful than making bronze of it.

Explanations there:
nature.com - scientificamerican.com - newatlas.com

[John Cuthber]

6 hours ago, Enthalpy said:

Lead from the roof shouldn't be discarded as ordinary toxic waste. It's precious for science, as a shield material against ionizing rays.

Freshly mined lead contains radioactive nuclides (elements and I suppose lead isotopes) from the parent nuclides that decayed into lead. They create background noise in the rays detectors. In old lead, most unstable nuclides have already disappeared.

Some experiments used lead from sunken antique boats. Several 100t of Pb, 800 years old, is a fabulous asset for science.

So far, that's just about the only thing Enthalpy has said here with which I agree.

There are two issues.

Decades of traffic will have dumped "new" lead on it and there will have been modern repairs.

But the original "old lead" is valuable as a low background screening material

Edited May 2, 2019 by John Cuthber

[Enthalpy]

A report by prof. Paolo Vannucci  told three years in advance that dust made Notre-Dame's attic highly flammable, that no extinguishing system was present, That the risk of fire was very high, and recommended to install some automatic extinguisher, optionally using powder.
(Italian) ilsole24ore.com
(French) marianne.net - liberation.fr

The French government acted exactly as it uses to and is known to act:

• It didn't let remove the dust.
• It didn't let install an extinguishing system.
• But it made the report secret "because it could inspire terrorists".

I wonder if communist Albania was as opaque and compulsory secretive as the French state is.

And the result is here.

The fire won't change the French state's habits. About lead oxide in the fumes, it acts presently exactly as it uses to.

Oh, and Pascal Paillard, head of the Materials and Metals Department at Nante's Institute for Materials, also tells that the smoke was yellow due to lead oxide. The same colour was observed in the cathedral fires of Reims in 1914 and Chartres in 1836, which had lead roofings.

2 hours ago, John Cuthber said:

So far, that's just about the only thing Enthalpy has said here with which I agree.

More to come

[John Cuthber]

On 5/3/2019 at 12:23 AM, Enthalpy said:

A report by prof. Paolo Vannucci  told three years in advance that dust made Notre-Dame's attic highly flammable, that no extinguishing system was present,

I think the  traditional response  is " No shit,  Sherlock".

Would you like to compile a list of  dusty  old churches where that was not the case?

[Enthalpy]

The cathedral's owner, that is the French government, was warned of the danger for an all-important monument, and got obvious recommendations. It didn't act. The catastrophe happened.

You mean, it's less faulty because the government does it often?

==========

The answer to early questions in the thread, "why was there no extinguishing system", is now known: carelessness.

Prof. Vannucci also answers an other interrogation in this thread, whether water would do more harm than good. He proposed powder extinguishers. Definitely less harmful than a destruction. Even occasional malfunction is tolerable.

[John Cuthber]

On 5/3/2019 at 12:23 AM, Enthalpy said:

The same colour was observed in the cathedral fires of Reims in 1914 and Chartres in 1836, which had lead roofings.

And my garden bonfire- which didn't.

The common factor is fire, not lead.

Some lead will have been boiled off into the air.

And, by now it will have been washed out by the rain into the rivers.

[Enthalpy]

But no yellow fume from dry oak in chimneys. It is lead the cause.

Presently in the lungs of people who breathed it. And on the clothes and walls, where it can still be removed.

[Enthalpy]

Why firefighters were called very late is better known now
nytimes.com

Notre-Dame had a very complicated fire detection setup, à la French engineering. When a first alarm rang, the look-out misinterpreted the detector location and sent the watchman to a wrong attic. Only a second alarm, half an hour later, let discover the fire location.

Why the firefighters made big efforts to extinguish the towers got a credible explanation too. Huge bells hang there at wood beams that were threatened by the flames. Falling bells could have collapsed the towers and more.

==========

I still haven't read what intermediate steps could let a cigarette or short-circuit light thick oak beams. Dust?

The investigators reason on technology from a century ago, as usual. No highly flammable substance was found "hence" the fire was not arson. Fabulous.

As if power lasers didn't exist for decades. They cut missiles from 200km range, so maybe someone could perhaps imagine they can light wood?

As if a monument known worldwide, symbol of a capital, bringing tourist flux, susceptible to damage worth billions, weren't an obvious target justifying high-tech.

No, not a century ago after all. Two millennia, hi Archimedes
wikipedia

Edited July 18, 2019 by Enthalpy

[Enthalpy]

More tinder for the ancient versus modern discussion, in this case, rebuild exactly as it was last modified, or modify again (...to what I add: complete eventually the cathedral, even if 8 centuries late, by building the spires originally planned on the towers).

The French president had wished to rebuild "even more beautiful in five years" and asked for architect proposals to replace the 19th century spire on the transept. The Senate, which has no final say but where the president has no majority, voted to "rebuild according to the last known visual state." The National Assembly voted the final text, removing this constraint, and apparently without a time frame, but organizing the use of the donations.
eurasiareview.com
france24.com

The Vatican had expressed their view that the cathedral has a mission for faith, and the reconstruction should observe that. At least, that's what I read, make your opinion:
aleteia.org
and admire how French newspapers transform that into "the Vatican wants an identical reconstruction" in title and comment despite their citation doesn't tell it:
bfmtv.com (in French)

Lead pollution is a damned good reason not to rebuild the roof as it was.

Edited July 18, 2019 by Enthalpy

[Enthalpy]

I had said that the yellow smoke was lead oxide, it is known now that hundreds of metres around the cathedral are polluted by lead, even if newspapers still put "molten".
I had said that the dense smoke had fallen down as it cooled, and you can see it on the pictures. The first 100m are not the worse location.
I would have preferred to be wrong. Tons of lead powder spread over a city are a catastrophe. Newspapers begin to discover the cover-up by officials.

en.rfi.fr - france24.com - medicalxpress.com
and the cited "investigation site" is nearly the only one in France that does more than pasting the AFP news
mediapart.fr (in French, and pay)
some sites relay the information
nouvelobs.com  (in French) - tellerreport.com

Between "10 times some alert limit", "800 times the legal limit", "child with lead levels in blood much higher than acceptable limits" and "astronomically high lead levels on adjacent roads, blood tests for children under 7 and pregnant women", the discrepancy is vast. I underline that no "lead safe limit" exists.