Houston stair well collapse, 3 dead 2

[Cool_Controls]

Anyone have any additional info on this?

Link

Better footage at this link
Link

 

[dik]

Any chance they were precast stairs being installed as the building went up, and the upper one wasn't secured and fell bringing the ones below it down as it continued its path downward.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik

 

[Cool_Controls]

 

[JohnRBaker]

One of our son's restaurants is right next door. He wasn't at that store today, but he says they've been watching the building go up for the last several months.

Disclaimer: Our son doesn't own the restaurant, just the he the corporate brand Executive, which means he's responsible for all of the restaurants in the group, three of which are in the Houston area, with 26 other locations around the country.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Cool_Controls]

Sounds like they pancaked all the way down to the first floor.
[URL unfurl="true"]https://www.nytimes.com/2020/10/05/us/houston-stairwell-collapse.html[/url]

 

[ATSE]

Damn precast. Again.

 

[dik]

I've done a lot of buildings with precast stairs...not recently, but used to be quite common... both site and plant... economical and excellent finish. If done correctly there is no issue.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik

 

[ATSE]

Quoting "... If done correctly..." Seems like famous last words. Better, this activity has high adverse consequences when not done correctly.
Which brought to mind an internet image (hopefully staged).

 

[Tomfh]

If done correctly there is no issue.

The point is that precast is far more vulnerable to mistakes than other types of construction, and mistakes happen.

 

[dik]

Not my experience...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik

 

[Agent666]

Any chance they were precast stairs being installed as the building went up, and the upper one wasn't secured and fell bringing the ones below it down as it continued its path downward.

I've seen some people only reinforcement precast stairs with a single layer of reinforcement at top or bottom to suit the final configuration and moment diagram. Effectively ignoring the fact that in lifting it into place the moments are often -ve moments, vs positive in the final configuration. having some bars at minimum cover in the bottom don't work too well bending the other way... When I pick it up in reviews, sometimes I get the precaster is responsible for the lifting design. Sometimes precaster does not have this expertise.


I see it as a safety in design issue. I always have two layers in my precast stairs to avoid any possibility of any issues with lifting.

 

[jayrod12]

My experience with them is much like dik's.

In Canada I have had nothing but good experience with pre-casters. In fact, the largest issues I have with a "local" pre-caster is one just south of the border that is shipping product north.

All of our specs are written such that the onus for the design of the item, including during lifting and erection is all on the pre-caster. And they do it well.

I read of the nightmare's you other engineer's have with pre-casters and can't believe it.

 

[dik]

...been involved with projects where the stairs have been site precast by the contractor and have designed them as precast.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik

 

[Tomfh]

Not my experience...

The failures are sufficiently rare that most engineers won't see one in their lifetime. That doesn't mean precast structures aren't overrepresented when it comes to accidents and failures.

 

[hokie66]

This is the first failure I have heard of that may be precast stairs. Is that definite? Precasting of stairs is a new one on me.

I agree with the adverse sentiment about precast in general, particulary for parking decks. It seems we hear about a couple of those every year...from failure to tie the bits together adequately. That brings to mind the one at Emory University in Atlanta, which was reported here in September. Best to report it in that thread, but any more news?

 

[dik]

Not uncommon... often precast apartment bldgs have precast stairs. Used to be more common 30 years back and often the contractor would opt for site precast stairs. If done right, precast is fine... as for parkades, the precast one at Polo Park in Winnipeg that I did about 30 years back is still holding its own... other than the ethafoam bars in the joints hanging down... If done correctly the high repetition and quality of finish with precast cannot be beat.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik