Miami Beach, Champlain Towers South apartment building collapse, Part 03 148

[SFCharlie]

A continuation of our discussion of this failure. Best to read the other threads first to avoid rehashing things already discussed.

Miami Beach, Champlain Towers South apartment building collapse

Miami Beach, Champlain Towers South apartment building collapse, Part 02

Thank you

SF Charlie
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[Murph 9000]

What were these two trunnion-like fixtures (one open, one closed) atop the columns used for?

I believe those are columns E2 & E4, and the western mounts for the large red HVAC support frame.

 

[gonefishing2]

So if anchor test broke what little bond there was between concrete mid wall cap beam, then elevator vibration for the rest of the day/evening, after test could have triggered the CMU in fill wall to fall. And folks were coming and going to their condos lated at night, so elevator would have been operating.

 

[gonefishing2]

Also what are the chances that once roof sheer wall was built they added penthouse, such that midspan elevator wall beam, spanned the whole way in one pour across the joined stair tower. A mid span lateral or diagonal pull on that beam would seem to cause deflection laterally in that beam in between block infill walls.

 

[Js5180]

The black horizontal band which I originally thought was open space, is actually roof tar. The roof over the 12th floor was attached directly below it. Also visible in the picture are the broken cores of the CMU blocks in the triangular hole.

 

[gonefishing2]

Js5180's picture also shows the broken column near tar line that anchor would have been mounted too....

 

[gonefishing2]

Looks broken at bottom and up higher where horizontal beam would have been. You can see in the cracked stucco the lines for the elevator horizontal beam as well as the stair well horizontal beam, all connected at column anchor area

 

[warrenslo]

I think the bolts that hold the anchor are tested with a device that applies the load to a very small area before the anchor itself is installed. See this post above: Ingenuity (Structural) 2 Jul 21 19:42 It's very unlikely this sort of test could have done enough damage to result in a large section of the wall falling spontaneously hours later. The bolt itself would come out because of adhesive failure, or a small section or concrete around the bolt/epoxy would have come out, both immediately obvious and of limited consequence.

Each fall-protection roof anchor assembly (post, plate, anchor bolts, etc.) must be tested before initial use and annually I believe per OSHA rules (see post above.) OSHA is unclear on the exact method of testing. The ultimate load is 5,000 lbs, design load is 1,250 lbs, so the industry standard is 2,500 lbs on each axis (X, Y, Z.) I personally believe this is a flaw in the OSHA rules, how can you place an arbitrary force on an existing structure which may or may not have been designed for such loads.

This testing is in addition to any epoxy anchor bolt testing required by the structural engineer.

The plans noting 5,000 lbs. testing of the epoxy anchor bolts is concerning to me as it seems each bolt would need to carry much less force than that.

 

[ChiefInspectorJ]

https://www.eng-tips.com/userinfo.cfm?member=jar546[/URL]]

Welcome from a fellow Inspector .Retired and tired. lets touch base.Please review some of my post.
Jeff

 

[ChiefInspectorJ]

Another apartment complex in Florida has been ordered evacuated as a precaution after city officials became concerned over a recent report about the buildings:

North Miami Beach building deemed unsafe, evacuations ordered

[highlight #E9B96E]A Jan. 11[/highlight] report on the Crestview Towers condominium complex said it "was structurally and electrically unsafe."
Politics as usual.

 

[ChiefInspectorJ]

https://www.eng-tips.com/userinfo.cfm?member=Roga50

Coverup is how many of these places operate.

 

[Mark R]

Another apartment complex in Florida has been ordered evacuated as a precaution after city officials became concerned over a recent report about the buildings:

North Miami Beach building deemed unsafe, evacuations ordered

This 1 is getting more confusing because I read another report earlier today that they have another engineer's review of the building which states that the building is safe. There is some work needed but nothing if life-threatening nor require evacuation of the building. Supposedly the engineer who did the 1st report was not a certified SI.

 

[lucky555]

Engineering as a profession has to stop blaming itself.
It started with the Iron Ring to keep us humble but that is being used against us now. We are surrounded by corruption and ineptitude all the while trying to build something safe.
We are given all the responsibility and yet have none of the authority to make it safe and keep it safe.

Developers cutting costs, adding features, moving around stuff, rush push hurry - all crank up the chances of a bad design, that the non-engineer developer is not responsible for. We're the fall guy, literally.
Construction missing rebar or using substandard concrete, failing to read drawings and instructions, cost cutting - all crank up the chances for bad construction.

Of course, as humans engineers make mistakes. But us having no balls to stop the non-engineers, such as Building Departments, Inspectors, Unsafe Structures, Condo Boards etc. from failing to properly maintain the structure needs to change. Even the "40 year" number came from a politician, not science.

If a building is not properly maintained, it doesn't seem to matter as engineers can still do NOTHING. Write a report and oh well. A building should never be literally run into the ground.

Although, it is best for Champlain that some engineering flaw is to blame, that does absolve everyone and place the liability off the town, condo board etc.

 

[FacEngrPE]

Hilti provides some guidance for Special Inspection testing of epoxy anchors, here is the portion on proof loads. My opinion is that when installing any anchor into degraded concrete, that becomes a limiting factor on the allowable test load. A good summary of the considerations driving the selection of a proof load is included.

https://ask.hilti.com/article/special-inspections-guidelines-for-post-installed-anchors/2jv5p4[/URL]]Proof loads – The establishment of proof loads should recognize the primary objective of proof loading as stated above, i.e., sufficiently high to provide assurance of correct installation but not so high as to result in damage. Given this objective, it should be clear that proof loads are set as a percentage of the tested tension capacity of the anchor, not the anchor design tension load. Historically, proof loads have been set at twice the allowable tension load. Given that the global safety factor used for anchor tension strength in allowable stress design has historically been set at 4.0 (inspected construction), the proof load represents approximately 50% of the mean ultimate anchor tension strength uninfluenced by edges, member thickness, etc. Note that, depending on the embedment to diameter ratio and the steel grade, this load might or might not subject the anchor to yield level stresses. For most mechanical anchor types using high-strength steels and typical embedment to diameter ratios (7 to 9), this is not a problem. Where lower yield steels are used, it should be verified that the proof loads do not exceed 80% of the nominal yield stress of the steel anchor components. Since the purpose of proof load is to verify proper installation, proof loading equipment may have load reactions close to the anchor but with sufficient clearance so any movement would be visible.

 

[Roga50]

Coverup is how many of these places operate.

Yeah. I'm not normally a "conspiracy theorist" but the way this thing was handled (the demolition) and the lies being told by the politicians begs one to ask what they are hiding. One doesn't blatantly lie like that without a reason. I mean, this "storm" they are so worried about--and STILL using as justification--I've lived through many of these. We'll lucky if we even see rain-the storm track is a LONG way from Surfside. The daily storms we get down here this time of year are about all we will see (and we saw them last week during the initial rescue attempts). It hasn't really been tracked for South Florida since even before the demo plans were made. And the lies about the pet searches (many have blown holes getting the politicians to contradict themselves). And the lies about the "rescue" vs "recovery."

The ONLY good decision they've made in this is they chose CDI, who I agree are the best in the business--if anyone could do this properly it would have been them.

As for this storm, anyone who knows me knows how seriously I take storms. I have a boat (which takes a day + for storm prep work) and a few other responsibilities for storms (my house, parents house, work). As such I have often been accused of being TOO careful for storms... This weekend I was replacing a fuel pump on the boat and running a few errands--no storm prep at all.

I have a simple rule: Don't lie to me. Don't tell me what I want to hear. Tell me the truth. I may not LIKE the truth, but I will respect you if you tell it. I don't shoot the messenger... (and the words "I made a mistake" gains even MORE respect from me). Lie to me (especially when you are a terrible liar) and I will NEVER respect you or believe one word out of your mouth again. After that, if you tell me the sky is blue, I will require peer reviewed studies before I believe you.

 

[pellucidar]

I don’t think anyone has mentioned the “plumbing” repairs done in 2017 to address leaking pipes in the garage, at least some of which had been invaded by roots from the entirely unwaterproofed planters (NBC Miami). This may coincide with the disappearance of the palm trees and the failed crack repairs.

 

[TugboatEng]

People don't like hearing that their loved ones aren't worth recovering. Using the storm as an excuse to complete the demolition is merely for optics. Remember the Hard Rock in New Orleans. It wasn't safe for body recovery so the remains of two individuals remained in the building, apparently visible to the public. Even my mother, some 2000 miles away with absolutely zero connection to the incident was deeply troubled for some irrational reason. She wanted a living person to risk their life to recover an obviously dead body which she never knew.

 

[Vance Wiley]

TWO PEOPLE SITTING ON THE BALCONY???

 

[ChiefInspectorJ]

YES!! I have studied it for 4 hours.

 

[KingBobo]

Here's the best available view of that balcony that I've been able to locate:

 

[Spartan5]

Here's the best available view of that balcony that I've been able to locate:

Well there goes another theory into the crapper.