Collapse of a building...

[Externet]

Hi.

Can the video recording of the event show if the lower structure failed first and the top structure dropped crushing on what was already collapsed;

or if the upper floors near the roof failed first and their consecutively fall on next floors under fractured them ?

A sink hole would produce the first behavior, right ?

[studiot]

21 hours ago, Externet said:

Hi.

Can the video recording of the event show if the lower structure failed first and the top structure dropped crushing on what was already collapsed;

or if the upper floors near the roof failed first and their consecutively fall on next floors under fractured them ?

A sink hole would produce the first behavior, right ?

 

It really is too early to tell with any confidence the mode of collapse.

 

My impression of the structure was that it was in three parts. laid out like a letter H for stability.

Often buildings of this type

Either the wings are more strongly founded and constructed and the central joining leg spans between them.

or

The central joining leg is the most massive and strongest, and the wings less so.

 

The point is from this sequence

https://www.bbc.co.uk/news/world-us-canada-57609620

 

The failure appears to have been a breaking of the connection to one side support starting the collapse of the central section, which then pulled the other side over with it.

The upper levels of the centre appear to have broken and fallen at one side, onto lower levels which then collapsed in on themselves in the middle under the extra weight.

There is a report that 15 years after the building was constructed (about 1995) it started settling or subsiding and has been doing so ever since.
There is another report suggesting inadequate drainage leading either washout or excess (clled active) soil pressure on the basements.

Either way if excessive differential settlement occurred and the centre lost sufficient of its support from one or both sides, collapse would occur rather as in the video.

 

But proper investigation will reveal much more, I don't doubt.

[studiot]

Further hard information available here

https://www.bbc.co.uk/news/world-us-canada-57651025

 

[Airbrush]

Anyone know how heavy a slab of concrete is over their head?  If you are on the first floor, you have that weight times the number of stories hanging over your head.  Concrete is the cheapest method of building, right?  What about Buck Minster Fuller and the geodesic dome?  What about the high structural integrity of a tetrahedron?  Bamboo is very rigid and grows very fast.  Why not have a light-weight grid of bamboo tetrahedrons between stories?  I was thinking of an exterior frame of steel I beams.  Upon that a framework of wood lumber, then between floors a lattice of tetrahedrons made from bamboo and other light-weight and flame-retardant materials between the floors.  Anyone know how to build a 12-story building without using concrete?

Edited July 5, 2021 by Airbrush

[TheVat]

If you have a frame of steel, then you need that frame to be girded with something fire-resistant, due to the possibility of steel members deforming or even buckling under great heat.  For mid-rise or high-rise buildings, I would think you'd want to avoid flammable materials, except as interior design accents. 

However, given the LEED pluses of bamboo and its low carbon footprint, it's certainly worth looking into possible ways to use it wherever feasible. 

 

 

[John Cuthber]

On 7/6/2021 at 12:41 AM, Airbrush said:

Anyone know how to build a 12-story building without using concrete?

This is close.
https://www.architecturaldigest.com/story/worlds-tallest-timber-framed-building-finally-opens-doors