Hard Rock Hotel under construction in New Orleans collapses... 119

[NOLAscience]

Former Jefferson Parish sheriff Newell Norman is interviewing Kerry Miller, the atty representing 1030 Canal St LLC

https://www.radio.com/wwl/listen

I am listening now and I will report back on interesting comments.

 

[NOLAscience]

The developer, “1031 Canal Development LLC”, had placed a newspaper ad Sunday that sought to place the blame on others for the Oct. 12 collapse.

https://www.nola.com/news/business/article_a08c1fa0-4064-11ea-8082-4361e0189135.html

 

[OHIOMatt]

I listened to the interview and what stuck me most is the following:
1. The contractual relationships on this project are interesting and seemingly complicated. From what I gather, 1031 Canal is owned by a family development company, the electrician for the project and the CEO of the general contractor.
2. The general contractor hired the architect who then hired the engineering consultants.

I am not 100% certain, but it sounds like this is design build. I have said it before, but I can't see how design build does not have inherent conflicts of interest built in. A few years ago, my state and I assume others issued a rule that contractors could no longer hire the special inspectors, and that they had to be hired by the owner to avoid the appearance of a conflict. How can the contractor hiring the design team be any different?

 

[gte447f]

OHIOMatt, I didn't listen to the interview, but your description of the contractual relationships of the ownership sounds dubious. Also, I agree with your sentiments regarding design-build. Personally, I have always thought design-build is a very flawed project delivery method.

 

[dauwerda]

A few years ago, my state and I assume others issued a rule that contractors could no longer hire the special inspectors, and that they had to be hired by the owner to avoid the appearance of a conflict. How can the contractor hiring the design team be any different?

Not sure if it matters in this case, where the GC is the owner (essentially).

 

[OHIOMatt]

dauwerda, I agree. This seems a little like the fox guarding the henhouse.

 

[ldeem]

I wonder from a legal perspective if the general partners of the LLC bear more financial exposure because at least one of them would be a knowledgeable about of construction. I can see a lawyer arguing the GC partner should have known there is a problem because he is experienced in construction.

 

[stevenal]

Piercing the Corporate Veil

 

[Boris_Kuznetsov]

The picture of the building after collapse corresponds to insufficiently braced frame with columns inclined to the middle of the building. It means that P-delta effect takes place. The Designer used effective length factor K=1 or less. Since the bracing system was not rigid enough, the effective length factor should be taken K>1.
ACI allows some plasticity in concrete floors including a full plastic hinge at supports. It means that effective length factor K can be significantly more than 1. This is a possible explanation of the building collapse.

 

[JAE]

Boris - so ACI provisions affect steel columns? Uh...OK.

 

[OHIOMatt]

Boris, there is a saying, “when you hear hoofbeats, look for horses not zebras”.

I think you are looking for issues to blame for the collapse, while overlooking the obvious. I would suggest you get a copy of the available, albeit likely superseded permit drawings and evaluate those. Based upon a quick review, I doubt you would come to the conclusion that the designer took into account plastic hinges and k factors.

 

[bnickeson]

The picture of the building after collapse corresponds to insufficiently braced frame with columns inclined to the middle of the building. It means that P-delta effect takes place. The Designer used effective length factor K=1 or less. Since the bracing system was not rigid enough, the effective length factor should be taken K>1.
ACI allows some plasticity in concrete floors including a full plastic hinge at supports. It means that effective length factor K can be significantly more than 1. This is a possible explanation of the building collapse.

What on earth...

 

[JStephen]

Re-reading that, I see some disconnect between Boris' post and the responses- he's saying the steel was designed assuming "fixed" base, but bases weren't fixed because the concrete is allowed to form plastic hinges, etc, and that the designers failed to take that into account.

 

[JAE]

I think Boris = Sue = same person.

 

[Boris_Kuznetsov]

I want to simplify my points. If the Designer wanted to design a braced frame, he had to provide a strong bracing system which guaranteed that all columns are not horizontally movable. In this case effective length factor can be K=1 or less. If the Designer wanted to design an unbraced frame, he had to calculate the factor K. In this case factor should be K>1.

In both cases the more slender is the floor, the more is factor K. The picture of the building after collapse shows that all columns inclined to the middle of the building, horizontally movable. I did not see the design calculations but suspect that the Designer used factor K=1 or less because his intension was to design a braced frame. If my suspicion is wrong, neglect this post.
If my suspicion is right, the design is dangerous and may lead to the building collapse. P.S. My goal is not to find who is responsible for collapse but to find its cause.

 

[jhardy1]

Boris,

If you're wondering why people are struggling to take your comments seriously:

Take a look at your expression for the column stability check that you posted on 26 December:

P < E c x bc x h x H / L (1) [Warning to casual readers - do NOT use this expression to check the stability of a column!!!]

where:
P - load on column,
E c - modulus of elasticity of concrete,
bc - tributary to the column strip of concrete slab,
h - thickness of concrete slab,
H - floor height,
L - span of concrete slab.

While dimensionally consistent, it makes no sense whatsoever.

Plug in some reasonable values for the various parameters, and calculate the resulting column stability load. What do you get? I think you will find it predicts a stability load of a million kilonewtons or more; equivalent to over 100,000 tonnes of applied mass - per column!!!

While there may indeed have been some errors or unconservative assumptions about column stability effects and slenderness ratios, these were not the primary cause of the collapse. As others have pointed out repeatedly here - the evidence suggests some gross deficiencies in the fundamental design of the floor slabs and beams as the root cause. Even if every column had been fully braced at every storey, the floor slabs were still going to collapse.

http://julianh72.blogspot.com

 

[phamENG]

And maybe they used the Direct Analysis Stability Method. K=1 for everything!

 

[moon161]

If you're wondering why people are struggling to take your comments seriously:

Take a look at your expression for the column stability check that you posted on 26 December:

P < E c x bc x h x H / L (1) [Warning to casual readers - do NOT use this expression to check the stability of a column!!!]

where:
P - load on column,
E c - modulus of elasticity of concrete,
bc - tributary to the column strip of concrete slab,
h - thickness of concrete slab,
H - floor height,
L - span of concrete slab.

This is crazy. Pcr increases with column length (H)

 

[Boris_Kuznetsov]

In my post of Dec. 26 I wrote formula:

P < E c x bc x h x H / L (1)
and got some critical comments. Here is my answer for these comments.
1) The formula belongs not to me. I got it from the theory of stability of elastic systems and implemented it to concrete floors.
2) The formula does not tell anything about the value of critical load on column. Nobody recalled the existing methods and corresponding formulas for calculation of critical load on columns.
3) The formula allows to determine if the floor can be considered as rigid support for column stability or not.
4) The results confirmed that for existing ratios of concrete span to thickness the formula is met and floors can be considered as rigid support for column stability.
5) The formula is correct and does not lead to any mistakes in calculations and design as written in some comments.

 

[moon161]

That makes some more sense to me then.