Building under construction collapses in George

Surely a building inspector (whatever they're called) needs to sign off and double check things as the building progresses... floor by floor.
They have to check the cement is correct, the mixing ratio, foundations xyz...

The amount of bricks there with no mortar on them seems very odd, someone skimped out on the cement / sand / water ratio. There is not even any brickforce in them!

FML what a disaster, that should be jail time 100%
 
There are obviously many things that could have gone wrong here. As mentioned earlier, could be design related, poor construction methods/standards or substandard materials. There was a cement supplier that had one of it's products banned in December 2023 for being "substandard". I suspect it will take some time before we get to definitive answers.

When we were building our new work premises in 2019, there was a sample taken from each batch of concrete and sent for testing. I would assume that is only one of many QC requirements on a project such as this.
 
Wrath of Khan said:
Surely a building inspector (whatever they're called) needs to sign off and double check things as the building progresses... floor by floor.
They have to check the cement is correct, the mixing ratio, foundations xyz...

The amount of bricks there with no mortar on them seems very odd, someone skimped out on the cement / sand / water ratio. There is not even any brickforce in them!

FML what a disaster, that should be jail time 100%
Click to expand...
Yes, but private residential developments can easily flout these requirements to save costs.
 
Civil engineer here, I've built many multistorey constructions, including some big offices in CT that maybe some of you are sitting in reading this.

First thoughts looking at the one picture are that the columns do not appear to have rebar at angle to tie into the floor at 90 degrees, so in essence, the floors have punched through them. From the pic the rebar is straight up and the floor is detached. Should be like this...

rebar.png

So the building looks like it's pancaked and the columns designed to hold the floors have been useless in stopping the loads bearing down on it. First thought again is this could be due to the floors not being given enough time to cure properly, so not reaching design strength and crucially, also not being supported properly during the time it takes to cure.

The formwork for the top floor needs to obviously be propped when the concrete is poured onto it. What is not always understood is what happens to the floors below. For example, and putting it simply, if the 4th floor has 100% props, third floor needs to have 50% props and second floor has to have 25% props. This is to distribute the loads through the floors and down the columns and down to the ground.

So if the 4th floor is cast and the 3rd floor has not reached sufficient strength and the props are not distributed properly or even removed, then this could lead to the loads being unevenly distributed and considering the columns don't appear to be supporting the floors, then this whole thing pancakes out one floor on top of the other.

I've had several near misses with people removing props because they don't understand the process, sometimes even during casting the top deck, someone two floors below has moved props hat get in their way.

Anyway, just a guess going on the one picture.
 
Spizz said:
Civil engineer here, I've built many multistorey constructions, including some big offices in CT that maybe some of you are sitting in reading this.

First thoughts looking at the one picture are that the columns do not appear to have rebar at angle to tie into the floor at 90 degrees, so in essence, the floors have punched through them. From the pic the rebar is straight up and the floor is detached. Should be like this...

View attachment 1704739

So the building looks like it's pancaked and the columns designed to hold the floors have been useless in stopping the loads bearing down on it. First thought again is this could be due to the floors not being given enough time to cure properly, so not reaching design strength and crucially, also not being supported properly during the time it takes to cure.

The formwork for the top floor needs to obviously be propped when the concrete is poured onto it. What is not always understood is what happens to the floors below. For example, and putting it simply, if the 4th floor has 100% props, third floor needs to have 50% props and second floor has to have 25% props. This is to distribute the loads through the floors and down the columns and down to the ground.

So if the 4th floor is cast and the 3rd floor has not reached sufficient strength and the props are not distributed properly or even removed, then this could lead to the loads being unevenly distributed and considering the columns don't appear to be supporting the floors, then this whole thing pancakes out one floor on top of the other.

I've had several near misses with people removing props because they don't understand the process, sometimes even during casting the top deck, someone two floors below has moved props that get in their way.

Anyway, just a guess going on the one picture.
Click to expand...
Yip. Civil Engineer here as well and that column head looks very suspicious.

Punching is definitely likely, especially as you suggest they may have unpropped their slabs a lot earlier for rapid construction.
 
buka001 said:
Yip. Civil Engineer here as well and that column head looks very suspicious.

Punching is definitely likely, especially as you suggest they may have unpropped their slabs a lot earlier for rapid construction.
Click to expand...

Yep. I've done a fair bit of rapid multistorey construction but it needs to have post tensioned cables and admixture to reach strength early. I've worked on 3 day turnaround for a slab, reaching 18MPa on 3rd day morning, tension the cables straight away and off we go with next set of columns formed and cast on day 4. And of course these cables mean a lot less rebar and lighter slabs but the majority of that rebar is round the columns to tie it into the slab properly.
 
The concrete on what is most likely the upper slab still looks "wet". Plus there seems to be loose, unused bricks from a pallet of bricks that were placed on the top of the slab.

I think @Spizz your speculation may be right, I think they removed the propping too soon and the slabs collapsed.
 

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Spizz said:
Yep. I've done a fair bit of rapid multistorey construction but it needs to have post tensioned cables and admixture to reach strength early. I've worked on 3 day turnaround for a slab, reaching 18MPa on 3rd day morning, tension the cables straight away and off we go with next set of columns formed and cast on day 4. And of course these cables mean a lot less rebar and lighter slabs but the majority of that rebar is round the columns to tie it into the slab properly.
Click to expand...

I watched a 3 storey apartment building go up across the road from our block, and it was done properly and took a long time. They used 100 times as much rebar as I saw in that photo...

Punching shear was a likely factor in that big Florida building collapse.
 
buka001 said:
The concrete on what is most likely the upper slab still looks "wet". Plus there seems to be loose, unused bricks from a pallet of bricks that were placed on the top of the slab.

I think @Spizz your speculation may be right, I think they removed the propping too soon and the slabs collapsed.
Click to expand...

Eish, I missed that photo. The perimeter brickwork looks to have taken place on the other pic so maybe props removed by the brickies? Not sure if that brickwork is load bearing but it looks like maybe the brickwork done before the slab is cast, slab insufficiently supported and boom. down it comes.
 
Looking at the photo of the construction, first thing to see is that formwork supported by scaffold is a huge no-no, and even worse, in this case it's a modular kwikstage type scaffold and not a more sturdy tube and clip. That's a straight up firing offence either way.

Also, it's blurry but top floor appears to be not cast as mentioned earlier, rebar sticking over the edges, floor seems supported by props underneath, see the arrow, but looking in to the floors below no evidence of props as mentioned earlier for load distribution during casting.

formwork.png
 
Wrath of Khan said:
Surely a building inspector (whatever they're called) needs to sign off and double check things as the building progresses... floor by floor.
They have to check the cement is correct, the mixing ratio, foundations xyz...

The amount of bricks there with no mortar on them seems very odd, someone skimped out on the cement / sand / water ratio. There is not even any brickforce in them!

FML what a disaster, that should be jail time 100%
Click to expand...
I could not proceed with building my garage until the inspector checked the foundations.

They checked and signed off on various aspects.

Surely, a building this size should have engineers signing off after each phase?
 
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