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-   -   Falling Dome Brick Photo - whaddya think? (http://www.fornobravo.com/forum/f8/falling-dome-brick-photo-whaddya-think-1040.html)

Fio 09-27-2006 09:45 AM

Falling Dome Brick Photo - whaddya think?
 
Photo of a falling brick in an oven made by an Italian "artisan"

I took a look at this picture and it looks to me like the oven was not built properly.

Whaddya think?

I am hoping this never happens to Forno Fio.

james 09-27-2006 10:15 AM

Ouch. As somebody else noted -- it doesn't even look like the brick was mortared in place. It's a nice looking, rustic, hand thrown brick, but wow; talk about an oversight.

I am thinking Forno Fio will be here long after we're gone. :D

James

Alf 09-27-2006 12:28 PM

An interesting photo had a look at it a couple of days ago. My guess is there’s two problems with the oven build.

1)The first row of bricks “solders” (some old furnace / oven guy from Stoke told me the name) won’t be sufficiently supported on the outside so have moved outward ever so slightly.

2)The end on bricks that form the ovens dome haven’t been place in the correct position so their joints aren’t crossed properly. In “bricky” terms the bonding is crap.

We once took apart a French oven that had four bricks come lose in the ovens roof. The problem there was that one weld had failed on the steel structural support and had allowed the roof / arch to move outward. The oven in the photo looks like a sloppy build by some one that didn’t have any pride in their work or regard for the ovens operators.

Alf

james 09-28-2006 07:32 AM

Outward thrust
 
This example, the Scott oven that fell in in Sonoma, and the high mass Pompeii oven questions all seem to have a common theme. Strong outward thrust compromising the structural integrity of the dome. Thinking back to the Scott design, I have always equated it with the Gothic cathedral, where the engineers used huge butresses (including the flying butresses at Notre Dame) to keep the walls from blowing out to the sides.

That's why the concrete cladding in that design serves two purposes. Increased mass, but also the butressing that literally holds the oven together, and keeps the low arch from pushing the vertical oven walls out. (Hey, all you need is some stained glass windows and you could hold services for a mouse inside your Scott ovens). Once the concrete fails, the dome pushed the walls out, and it falls in.

To a lesser degree, the very steep oven dome you see in the ovens build in Naples (or by Napoletana muratore travelling around Italy) can have that same issue. They go straight up for a full brick height, then angle sharply into the parabolic disk shaped dome. I can see how outward through could compromise one of those ovens if you weren't careful.

The typical Tuscan oven found around here (the Artigiano is a good example of that style) has a slightly higher dome, and a more gentle arch that starts earlier, making the dome more self-supporting.

The duomo in Florence is a great example of a dome that will stand forever, without external butressing.

The Pompeii oven certainly has a lower arch than the Duomo, but you can see the analogy -- and I think from building it you get the feelinig that the walls won't blow out.

Interesting.
James


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