Christopher:
2. I’m guessing they cut the joists (and rafters above) from the basket so that wouldn’t be as scary as doing it from the floor. It had to be slow going though.
3. Some sort of wainscoting treatment? Maybe they were hiding failed plaster. There doesn’t seem to be any plumbing to hide there (the studs would have been
notched). It hides the electrical circuits without using Wiremold?
4. A floor is a sort of composite structure with the subfloor running perpendicular to the joists (and maybe to some degree the lath of the ceiling below)
forming the skin. It might be tied into the wall in some way and that may be helping. There may also be a (previously) non-structural wall below that is helping out.
5. I don’t know a lot about this type of construction but I find it pretty scary. I think I see a steel beam in the third floor level but no steel column at
the party wall (I hope there was a pilaster of some sort there but that doesn’t appear to be the case). There doesn’t appear to be what I think is called a shear wall or significant diagonal bracing. There is strength in numbers--lots of smaller elements that
add up to equal a structural element of sorts.
6. I think that’s what you’re seeing.
I’m a little surprised they wouldn’t try to shore it up rather than tear it down but we saw the same thing happen when an old building in Cortland (NY) burned.
In that case the heat from the fire probably weakened the mortar adding to the impetus to tear it down ASAP?
Bruce (not a structural engineer but still wondering when I get to drive the train)
From: The listserv where the buildings do the talking [mailto:[log in to unmask]]
On Behalf Of [log in to unmask]
Sent: Tuesday, July 10, 2012 3:44 PM
To: [log in to unmask]
Subject: [BP] building collapse in Brooklyn
I wonder if other subscribers could tell me a bit about what I'm seeing in the photo (mid-way down, left side) of a building collapse in Brooklyn. The "collapse photo"
looks from the backyard towards the front, and shows the failure of an original party wall - exposed when the house originally on the right was demolished, perhaps 60 years ago.
1. So the party wall somehow crept away from the joists and finally went - correct? Or could it have been a failure at the corner? Could freeze thaw - introduced
small debris into the beam pockets - have played a part?
2. The joists in the corner of the building seem well far back from where they would have met the wall. Do they not appear freshly cut, or some of them? That would
have been rather hazardous, no? Or am I missing something about them?
3. On the top floor, first room in on the right, I gather that I am seeing studs or something else constituting the inside wall of the room. So then what is the
half-height item one floor below?
4. The joists in the room in the second floor down project out fairly solidly, without the near fatal deflection I would have thought. Is that a testament to friction
and inertia?
5. So, OK, let's say party walls in principle are just fine - although 12" or 18" or whatever seem wildly inadequate to me. So, let's say we tear down a mate.
Is a party wall >>really<< meant to stand without it's mate? What if it were a simple end wall? Even thinner?
6. On the third floor down, second room in, the joists are sort of intact, but there's also this sort of framework, peeling off - as it it were a hung ceiling.
But ... with wooden 2x4s?
It will be interesting to hear about the condition of the hitherto hidden party wall, when it is exposed by the demolition of this structure. "Lucky" said Tim Lynch
- you bet!
Christopher
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