Apartment Building Collapse 46

[dik]

"A six-story apartment complex partially collapsed Sunday evening in the city of Davenport, Iowa, authorities said. It was not immediately clear if there were any fatalities or how many people may be missing or trapped in the building.

Davenport Mayor Mike Matsen said there were "several people unaccounted for," but did not give a specific number or range.

The collapse happened shortly before 5 p.m. local time, Davenport fire chief Mike Carlsten said. The cause of the collapse was not immediately clear."

https://www.cbsnews.com/news/davenport-iowa-building-collapse/

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[sgw1009]

Here is another copy of the collapse video, this one with slightly higher resolution:

https://www.kcrg.com/video/2023/06/02/video-showing-davenport-apartment-beginning-collapse-released/

 

[Jeff Ostroff]

I mentioned in my video analysis last night of all the photos taken the day of the collapse just hours before by Shaffer, who turned in a bid for the job but was rejected for a high price, that the contractors failed to adhere to the bracing drawings that the engineer drew up. I showed both the drawings and the photos and the bracing that was in place is 100% ineffective and incorrect. Shaffer had gone there on Sunday and warned workers to leave, they were going to die if they stayed.

 

[Sym P. le]

It might have to be pointed out that what differentiates this building from many others is that the west masonry wall was load bearing, supporting the interior structural steel frame.

Once the century old masonry units lost their bearing capacity, they all required replacing, i.e., the entire west wall required replacement.

 

[bones206]

Jeff do you have a link to your video?

 

[Jeff Ostroff]

Yes the video is here:

https://youtu.be/BQilJsOCV44

 

[SWComposites]

Those “braces” in the photos are absurd. I would use more robust braces for a simple home project.

 

[FacEngrPE]

Jeff Ostroff'S "non technical" analysis seems spot on.
The geometry of the installed props is completely different from the engineers sketch. The lower end is so far out from the building the force vectors at the top end have too large a horizontal component vs the vertical component to provide useful support. As installed they (the props) likely will slide from any vertical loading.

 

[gte447f]

The shoring that was installed had no chance of supporting the loads involved. You can see in the video linked above that it all simply buckled when the collapse happened. It makes me think that those involved in the repairs did not fully understand the magnitude of the structural deficiencies or the magnitudes of the structural loads that they were dealing with.

 

[hokie66]

The painter did a good job.

 

[Sym P. le]

3D from drone video KROC 1340/96.9

 

[XR250]

that the contractors failed to adhere to the bracing drawings that the engineer drew up.

Would that shoring have worked anyway?

 

[gte447f]

Would that shoring have worked anyway?

Not a chance. I highly doubt it.

 

[gte447f]

So, I have not looked into this at all other than what I have learned from reading this forum thread. Can someone clarify the type of construction? Was the exterior wall that collapsed load-bearing, multi-wythe, brick, masonry?

 

[Jeff Ostroff]

Hi XR250, The shoring that would have worked anyway, is the shoring that was shown in the drawing from the engineer back in February as shown in the photo here. The large sheets of plywood pressed up against the breakfast spade and held in place with braces that are staked into the ground, would have kept the bricks all in plain and they would not have buckled outward and fallen

 

[Sym P. le]

Was the exterior wall that collapsed load-bearing, multi-wythe, brick, masonry?

All of that is still unclear. The following report is the start of knowledge and a number of vague images appear throughout the documentation.

Structural Report

It is unknown if there is a north-south steel beam inside the wall at the second floor level, or if there is a steel post encased in the brick which supports the encased east-west beam. It will therefore be conservatively assumed that the east-west beams bear directly on the brick wall to be replaced. This is further reason to replace the wall in smaller segments to minimize the area and duration of unsupported walls above. If, however, steel members are encountered during demolition, they are to be preserved and undamaged.

 

[gte447f]

Jeff Ostroff, I am not sure if you are saying that the shoring as sketched would have worked or not, but I think it is a little premature to say that it would have definitely worked. That sketch looks like what I would consider schematic in nature. There are some important details missing from that sketch, like the permissible angles of the braces, the maximum permissible length of the braces, the fastening requirements of the anchor cleats to the ground, the size and maximum permissible length of the steel angle, etc. Also, I personally have always had questions about the logic and the practical construction considerations of installing an angle into a kerf cut. What holds the masonry up temporarily until the angle can be put in place in the kerf cut? This especially becomes problematic if the masonry is in poor condition like it was in this case.

 

[Sym P. le]

From the NEST camera video, the foreground brace bows considerably prior to the collapse.

 

[IRstuff]

Can't see how the sheathing would have done any more than the coating of paint the previous owner applied. The interior wythe looks so deteriorated that someone sneezing at it might have caused the collapse; it looks like the only thing holding up some of the brickwork was the mortar

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[hokie66]

You are right, IRstuff. And those toothpicks which were used as struts were just too skinny to help. Neither the detail by the 'engineer' or the as built detail had a chance.

 

[Sym P. le]

The problem isn't the exterior skin, it's the failing load bearing interior brickwork. As the building settles, it bulges the exterior brick. They are playing with a symptom and missing the problem.

The structure nearest the camera which was rehabilitated remained standing. The unaddressed portions adjacent and north failed, lacking timely intervention.