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"Doomed" Las Vegas Tower - Structural Blunders
17

"Doomed" Las Vegas Tower - Structural Blunders

"Doomed" Las Vegas Tower - Structural Blunders

(OP)
Someone's in trouble...just not sure who:

Doomed Tower link

RE: "Doomed" Las Vegas Tower - Structural Blunders

Be interesting to get a copy of the drawings... just to see what is not 'constructable'... coincidentally, I understand that the unemployment in LasVegas is in excess of 20% and that things have ground to a halt in that town.

Dik

RE: "Doomed" Las Vegas Tower - Structural Blunders

Wow, sounds like a culmination of errors committed by multiple parties.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Having read this article, I would say the majority of the fault lies jointly with the steel erectors and the third-party inspection company.  

The steel erectors should have notified the general contractor, who wouold have thus notified the structural engineer and maybe something could have been worked out, rather than just not istalling the steel anchor supports.

And shame on the third-party inspection company for falsifying all of those reports.  Sixty-two falsified reports, where one falsified report is unacceptable.

However, this will be backlashed onto the structural engineering company, and the argument is going to be that they supposedly never visited the project site to perform simple progress check-ups.

All-in-all it will be interesting to see how this whole thing gets resolved.

RE: "Doomed" Las Vegas Tower - Structural Blunders

ABP...as is usual.  In construction failures, there's rarely one culprit.  In many projects that get built, they do so in spite of the three main parties...architect, engineers, contractor!

In 34 years, I have yet to find a flawless construction project.

This one will be litigated for a long, long time.

Thanks for the post, JAE.

RE: "Doomed" Las Vegas Tower - Structural Blunders

I won't post a link here, but if anybody wants to look at the credentials of the third party inspectors, you may wonder as I do why a firm of geotech and materials engineers were appointed as structural inspectors on a complex concrete highrise.  

RE: "Doomed" Las Vegas Tower - Structural Blunders

Call me crazy but I always like to have the guy who designed the building also to be the inspector. stuff this third party situtations.  

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION."
 

RE: "Doomed" Las Vegas Tower - Structural Blunders

62 falsified reports is disgraceful and negligent. Thats the type of corruption I would expect to see oversee's but not in the US. They should throw the book at everyone. The builder, the inspecting engineer, the building certifyer and anyone who was aware there was dodgy practices going on and didn't say anything..

I guess it's okay that this negligence has only cost a property developer a couple of hundred mil US, but this could have cost someone their life.

RE: "Doomed" Las Vegas Tower - Structural Blunders

rowingengineer,

I do agree with your statement, but unfortunately that could be perceived as a conflict of interest on some level.  Especially if you have to follow Chapter 17 of the IBC, a third-party "special inspector" is required.

kikflip,

Unfortunately, the ones who will get the brunt of it will be the structural engineer and the general contractor.  Most third-party inspection companies aren't really large enough to provide some sort of back-pay and face any level of fines...and usually fold right away to cover the inspector's owners and professional engineers...if they even have any professional engineers on staff to oversee the inspection crew.

Just my general opinion on this whole matter.

RE: "Doomed" Las Vegas Tower - Structural Blunders

We have had this discussion about third party inspection before.  I don't know what is so special about "special inspectors", but it seems to be popular among US engineers these days (not when I worked there).  Like rowingengineer, I think it is a detestable situation.

RE: "Doomed" Las Vegas Tower - Structural Blunders

"Special" inspectors are not very special afterall. I have countless stories of negligent/incompetent/"I don't care" special inspectors on projects that I have designed/worked on.

I don't believe there to be a conflict of interest. I don't think that we structural engineers are so negligent that we will let something slide by just because we are also the engineer-of-record. If there is a team of people that know the project inside-out, it is the structural engineer.

We do a lot of our own inspections in South Florida on Threshold projects. Our office policy is such that the person who designed the project (project engineer) is not the person doing the inspections. The inspector is someone within our own office (an EIT with 2-3 or more years of experience) who has strong engineering knowledge but no project knowledge. The goal is to inspect what is on the drawings and also sometimes to question "suspect" details and discuss it in the office.

I believe we strive to make our structure as safe and as constructable as possible. It also helps the project go smoother because there is always a direct line of communication between the "design team" and the "inspector" which is not often the case when you have "third-party" inspectors who have to follow round-about protocols to get problems corrected or questions clarified.

Enough of the rant, IMHO I think the third-party inspections is bogus.

RE: "Doomed" Las Vegas Tower - Structural Blunders

I agree with almost everything that slickdeals says above.

I see no conflict of interest for this type of thing - we are not awarding contracts only ensuring that the building is safe. If it is safe no problem, if it is unsafe then it is the engineers door that will first be knocked on.

I am a strong advocate of the person who designs the building doing the inspection for a couple of reasons.

Firstly, it gives a direct route for important feedback and learning. How is a graduate engineer expected to get an understanding of what works or doesnt work on site unless they are involved in the inspections.

Secondly, there is no such thing as a perfect design. Any flaws are much more likely to be picked up on site by an educated pair of eyes that understand the way the building is designed to work.

Lastly, they are probably the most appropriate person for the job.

RE: "Doomed" Las Vegas Tower - Structural Blunders

I know (and used to work for quite some time ago) the structural engineering firm named in the world architecture news article They have a significant history of technical expertise on large, complex projects around the world. I don't know any details of this project other than those in the article.

In my experience, complex details need to be worked out at the design stage and sometimes the design intent may not be clear to a contractor or an inspector (3rd party or not) who is not intimately familiar with the intent of the details. I have witnessed how much work has gone into complex rebar layouts at the design stage with 3D models and such to try and assess constructibility. There have been instances I have been involved where contractors and inspectors, under the pressure of time and $$$ (or through lack of training), make subtle field modifications, that on the surface appear reasonable, but create conflicts with the original design intent. I am a big fan of keeping the EOR informed of ANY design changes in a timely fashion. Sixty-two falsified reports is totally unacceptable and misleading.

RE: "Doomed" Las Vegas Tower - Structural Blunders

First of all, Las Vegas has a system for qualifying special Inspectors.  It's actually more rigorous than most. This really discourages firms from performing their own Special Inspections, which I believe was the intent of the code.
The VP of the Special Inspection firm has had his license suspended by the State of Nevada. We've worked with them, as a Geotechnical Firm, extensively. I've met him.  He's a good man and a good engineer. I'd sure like to hear his side of the story.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Our firm has not performed special inspection services before but we have worked with third-party inspectors before on the projects that we have designed.  We do perform regular site visits to follow progress, answer contractor questions and address constructability concerns.
I will say that communication is key and it is imperative that inspector qualifications be reviewed by the owner and design team.

I'm not totally opposed to third-party inspectors as they have been very helpful and the special inspection process can be very time consuming.  The third-party guys that I have worked with have been very active in the problem solving process when issues arise and I have learned a lot from them and the contractors for that matter.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Having the special inspectors work for the EOR is infinitely superior to having a third party inspector. The EOR is "in the loop" when inspections are scheduled through his office, he can track the progress, notify the inspector when critical-complicated items will be coming up, he will see the reports in a more timely manor and there is a direct line of communication between the inspector and the EOR.

From personal experience, whenever I have a third party inspector on one of my jobs, I almost never get any calls from the field or comments on the reports that they found anything to be non-conformant. When my own people do these inspections, I get multiple calls every week asking if something is OK, or if something needs to be fixed.

Sophisticated owners recognize the value of having the inspector work for the EOR, but all to often, they see the bottom line and go with the low-ball number. Many just don't understand the impact of using an un-certified concrete tester as their inspector.

Perhaps projects like the one highlighted in this thread will wake some people up- but I doubt it.
 

RE: "Doomed" Las Vegas Tower - Structural Blunders

I believe the EOR has always been able to act as the approved agency for special inspections. (I do not have my 2003 or 2006 IBC handy.) The IBC 2009 section 1704.1 has been changed to read "...The registered design professional in responsible charge and engineers of record involved in the design of the project are permitted to act as the approved agency and their personnel are permitted to act as the special inspector for work designed by them..." No doubt to clarify the issue.

Garth Dreger PE
AZ Phoenix area

RE: "Doomed" Las Vegas Tower - Structural Blunders

As with most articles in non-professional magazines, this seems to jump to lots of conclusions without even trying to understand the full story. A complete peer review of the original design and an extensive as-built survey may be necessary to come to any reasonable conclusions about what is wrong with this structure. But that makes for a technically accurate but boring article.

And why would a steel structure ever need to be demolished if there are structural problems? You can modify a steel structure in an infinite amount of ways once its built, I imagine at a fraction of the cost of demolition and rebuilding.

Special Inspection- Though I like the idea of in-house special inspection (done by the EOR), that is not always logistically feasible. If the project is 2+ hours away and you are a one or two man SE firm, occasional observations may be the only service you can provide. Second, many E and O insurance policies specifically exclude INSPECTIONS without a modification to your policy.

RE: "Doomed" Las Vegas Tower - Structural Blunders

@a2mfk

The structure in question is CIP concrete.  The deficiencies were in rebar.

RE: "Doomed" Las Vegas Tower - Structural Blunders

ahhhhhhh, I stand corrected. I was thrown off by: Perini Building Company's subcontractor, Pacific Coast Steel.

But I suppose rebar is steel now isn't it...

Carbon fiber maybe?? A whole lot harder to know exactly the field conditions when they are covered with concrete!

RE: "Doomed" Las Vegas Tower - Structural Blunders

From what I heard, they did a lot of NDT to determine what was in place and that's how they determined where the new height would top out.  It's a weird situation because the floors they removed were residential units that weren't selling and MGM is probably glad they didn't build them...and Perini knows this.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Knowledge is not only difficult to be brought into the minds, it is also difficult to bring to the works. I perfectly understand that something as complex as our buildings and constructions are not entirely in the reach of almost anyone in the world. Yet traditional (middle ages) practice was that someone, a contractor-architect-designer, fared with the representation and risks of construction. Since then we have not made other thing that spread more and more abilities and liabilities between different trades.

Some of the "late" implementations such project managers and third party inspections may be -not neccesarily are- truly invasive and disruptive of the traditional ways, particularly in chain of command and some aperture to the "politics" and "economics" of getting commissions, fees, etc.

Not that this only happen to designers; european contractors may be forcibly required to bring the financing of big works or maintenance of the same for say 20 years, making the bank an uninvited guest to their dish.

I am wary of such aperture that can turn in a field of mines able to do away with entire sucessful, profitable and responsible practices and firms, and I have seen cases where these purportedly neutral interventions, and maybe protective of public interests, lead to the realization of the dangers above stated.

Particularly worrying is that some of the outfits are (sometimes transparently, i.e, "invisibly") manned by cheaper scarcely trained professionals, or even if trained, with so little practice or common sense that they themselves are a risk; everyone that can punch the cards, er, make the input to some program is already the nicest engineer.

In many cases, 3d party intervention is a logical requirement, and not even such concern as Foster's can think be logical to take it all to make something in Las Vegas in accord to customs and laws they are not customarily practicing (something entirely common for international practice except for delivering ready-made facilities, I think). Hence some must decide that from construction design and later they just better look from the distance. And sometimes must be a sight.

RE: "Doomed" Las Vegas Tower - Structural Blunders

4
It's really kind of hard to see through the spin here.  If the reports in question just said everything was okay when it wasn't, is that a "falsified" report?  Was there some kind of scheming going on with those reports, or just failure to recognize or call out problems?  Was the steel placement a "blunder" or was someone following conflicting details along the wrong line of interpretation or what?  You can tweak the wording on some of this and change the impact of the story considerably.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Plus, if you read the Las Vegas Review Journal article linked above, Perini is claiming that;
"Perini counters that structural drawings for Harmon 'were months late and contained many errors and omissions,' adding that MGM Resorts 'would have to acknowledge that the permitted set of drawings never matched the sets of drawings (used) to construct the project.'"
Was this project so rushed that they didn't have drawings to build from?  
I think that MGM found out in the middle of the project that it was going to be a money loser.  They're litigating their way to cover part of their investment.

RE: "Doomed" Las Vegas Tower - Structural Blunders

You know, this being in Vegas, they should just build it to the full original height, put a big sign out front that says "40% Chance This Building Will Collapse In The Next 50 Years- Do You Feel LUCKYYYYYY?"  People would flock to it and buy the T-shirts.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Rowingengineer...

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO MAKE THE CONNECTION."  

Dik

RE: "Doomed" Las Vegas Tower - Structural Blunders

Quote (JStephen):

If the reports in question just said everything was okay when it wasn't, is that a "falsified" report?  Was there some kind of scheming going on with those reports, or just failure to recognize or call out problems?

J, you received a star. You have made a very good point and I thank you!  To be honest I assumed that the act of fraud and misrepresentation had taken place.  Is this a fact or am I jumping to the wrong conclusion? Could the inspection have inadequate because of inspector ignorance or inspection criteria the inspectors are reporting to?  Should I believe newspaper reporters as always correct who have verified their statements and context to avoid slander?

JedClampett, I gave you a star also.  Yes, there are 2 sides to every story. It is usually the good ones that die first.

What are the requirements to become an inspector, how are the inspectors qualified, who qualifies the inspectors, who is overseeing the inspectors?  What was the inspection criterion and did it include the issues deemed unacceptable?

I have a hard time believing that reporting errors (intentional of unintentional) where made by that many inspectors and everyone turned a blind eye to it. There is usually a whistle blower in the pack.  Perhaps this is how the condition came to light and the whistle blower is now included in the Las Vegas 20% unemployment stats pointed out by DIK.

IMHO, fraudulent, intentional, misrepresentation of inspection results should be punishable by law, include a fine and jail time.  Punishment should also be extended to the entity paying and employing the liar.  I say this but on the other hand I do feel for inspectors who have a family to feed and want to do the right thing but are pressured or mislead otherwise.



 

RE: "Doomed" Las Vegas Tower - Structural Blunders

Quote (rowingengineer):

Call me crazy but I always like to have the guy who designed the building also to be the inspector.

I don't think you are crazy.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Quote:

vanmorrison

And you get a star because I love your music!

pimp

RE: "Doomed" Las Vegas Tower - Structural Blunders

Abusementpark, thanks bud!

bigsmile bigsmile bigsmile bigsmile bigsmile

RE: "Doomed" Las Vegas Tower - Structural Blunders

It frankly looks more an economical problem than a constructive one ... 1.5 billio dollars? The building seems not to have the size to recover such amount by any means.

RE: "Doomed" Las Vegas Tower - Structural Blunders

The video doesn't help much in understanding the problem.  The language used ("reinforcing the cement"), etc. doesn't give any confidence in the reporting.  The other reference talks about congestion in beams which are 8' thick, which may mean 8' deep, but that is just a guess.  The most common place for congestion problems in towers is in core coupling beams and outriggers...  

RE: "Doomed" Las Vegas Tower - Structural Blunders

From the video, it seems there were two rows of bottom reinforcing but the constructors took some from the centers of the rows and put them higher up on the sides of the beams. It sounds as though there was a large proportion of steel, probably lots of stirrups near the ends making it difficult to add the inner bars.

We used to build physical models of some congested joints in a couple of the nukes that I worked on. It made planning the rebar installation so much less difficult.

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: "Doomed" Las Vegas Tower - Structural Blunders

These quotes from Hokie's article tell the story, I believe:

Quote:

They found that the Harmon's third-party inspection firm, Monrovia, Calif.-based Converse Consultants, falsified 62 daily reports between March and July of 2008 stating that things were OK when they weren't. County inspectors missed the problems, too. It seems rebar was misplaced inside link beams that transfer horizontal loading to the building's shear walls. A shear wall is a braced panel wall that counters lateral loads on a structure. In other words, it supports the building and keeps it from falling over.

Stirrup hooks, ties that hold rebar together, also were spaced incorrectly, county investigators found; some even poked past the floor slab, prompting workers to cut them off with a blowtorch so they wouldn't show.

"We do not see this very often," county building official Ron Lynn said. "They installed it wrong. That's the bottom line."

Quote:

Harmon's design called for pouring top portions of the 8-foot-thick link beams with the floor slab, which is a tricky procedure given the tight and exact spacing of rebar.

Quote:

Harmon workers reportedly moved rebar without first getting an OK from the structural engineer, Halcrow Yolles, which is a major no-no in the construction chain of command. Rebar placement is carefully configured to maximize structural building strength.

"Congestion, or too much rebar matted together, prevented proper coverage and distribution of concrete," said a project official who requested anonymity.

Quote:

Perini counters that structural drawings for Harmon "were months late and contained many errors and omissions," adding that MGM Resorts "would have to acknowledge that the permitted set of drawings never matched the sets of drawings (used) to construct the project."

While it doesn't quite sound like the structural engineer is completely off the hook here,  there seems to be a lot of overwhelming evidence that the rebar sub and the inspectors were the major culprits here.

How this went on for 15 floors of construction is beyond me.  Did the EOR not made a single pour visit the entire time?  I understand sometimes you are specifically not hired to perform construction administration.  However, on a building of this magnitude, an engineer should never allow complete separation from the construction process.

Oh well, at least it was a successful project for the lawyers.

RE: "Doomed" Las Vegas Tower - Structural Blunders

It was my practice to consider constructability in my designs. Over the phone, or in a meeting, I would tell the fabricator/erector, off the record, what I had in mind when i made the design. I would tell them that I would make changes to accommodate different "ways and means".

Then, after the lawyers and the insurers became involved, we were instructed to stay away from means and methods, it belonged to the Contractors and our insurance didn't cover it. The weird thing though, was that one of our construction managers would look it over for an independent QA constructability review. Unfortunately, they were senior, desk-bound guys who hadn't been in close proximity to actual construction work for eons.

Oops, this started out as a caution, the GC says they were working to drawings different to the sealed permit set. We don't know if the EOR was consulted about the changes. We don't know what drawings and documents the Inspectors were using. It looks certain that the owner miscalculated the demand for condos and is trying to call it a loss due to the faulty work, etc. etc..

A personal note; I hated working on jobs implementing the designs of "Great Architects".

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: "Doomed" Las Vegas Tower - Structural Blunders

"...the permitted set of drawings never matched the sets of drawings (used) to construct the project."

Considering the terrible housing and construction market in Las Vegas, and without saying which parties were at fault, how could anyone expect the above situation to end well?

RE: "Doomed" Las Vegas Tower - Structural Blunders

3
(OP)

Quote (paddingtongreen):

A personal note; I hated working on jobs implementing the designs of "Great Architects".  

A star paddington! - I've seen the same frustration - but that struggle is either because:

1.  The "great" architect was really quite incompetent when it came to constructable details, or,

2.  The "great" architect was designing something unique, and in doing so was pushing the engineers to stretch their designs as well and design something unique as well, or

3.  a combination of 1 and 2 above.



 

RE: "Doomed" Las Vegas Tower - Structural Blunders

One thing that confuses me (actually a lot of things confuse me) is on the news story that JStephan linked.  I realize that there is nothing more superficial than a local TV news story.  But the example the construction professor shows in the story was that the horizontal bars in the shear link(?) were incorrectly placed and the stirrup (tie?)spacing was too far apart.  If that were my project, I would be doing some serious pencil sharpening to make that work.  If the links are tension members, is the bar location and stirrup spacing really that important? And isn't there some room for interpretation either way? Note that Las Vegas is a pretty low seismic area, corresponding to the old Zone 2B.
With hundreds of millions of dollars at stake, I wouldn't mind getting a cut of it to do an as built analysis of the structures.  It seems that tearing them down is pretty drastic. Fifty or sixty million dollars in repairs could go a long way.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Jed,
The nomenclature used in those articles is "link beams".  I don't know what that is, although I suspect they could be core coupling beams.  If that is the case, both shear and moment are high, and the placement and spacing of the bars is critical.  One of the articles also said that the issues with the building are well known in the structural engineering community worldwide, but I must have missed it.  Anyone?

RE: "Doomed" Las Vegas Tower - Structural Blunders

Quote:

The nomenclature used in those articles is "link beams".  I don't know what that is, although I suspect they could be core coupling beams.  If that is the case, both shear and moment are high, and the placement and spacing of the bars is critical.

Yep, that was my interpretation as well. In one of the articles I read, they stated that the mistakes had implications on the lateral stability of the building.

RE: "Doomed" Las Vegas Tower - Structural Blunders

link beams is a pretty common term for coupling beams in the US

RE: "Doomed" Las Vegas Tower - Structural Blunders

Unless there are other problems, for the cost involved, it might be worthwhile to try to reinforce the beam...

Dik

RE: "Doomed" Las Vegas Tower - Structural Blunders

In regards JedClampett's statement about pencil sharpening:
How much pencil sharpening room is there for tall structures like this?  
At our company we work on smaller scale projects and the majority of the calcs are done by hand and thus there is usually room for some pencil sharpening.  However I don't have much experience on tall structures such as this, where I'm guessing the design was computer aided.  Is there typically still some room for "pencil sharpening"?

Thanks

EIT

RE: "Doomed" Las Vegas Tower - Structural Blunders

One thing for sure is that the architects Foster and Partners will wriggle out of this one.

They were involved with the Millenium Bridge in London.  The lead consultant was the engineering consultant Arup who asked Foster to get involved with the design.  Suddenly Foster muscled their way up to being lead consultant.  When the bridge opened there were serious problems with dynamics from irregular foot fall and the footbridge was swaying all over the place.  Guess what happened next - Fosters decided they were no longer the lead consultant and handed the job back to Arup.

Sophistocated dampner costing £5 miilion fixed the problem.  Foster was nowhere to be seen.

RE: "Doomed" Las Vegas Tower - Structural Blunders

4
I have to agree with several posters above.  In my experience threshold inspectors in Florida are even worse than the city and school board inspectors.  Every job I walk on to I find all sorts of mistakes.  I almost hate going to the job sites these days as it generally creates more work for me and gets me all depressed.  If you have any special details then the structural engineer of record had better at least take a peak at the project in person.  

Rule #1 - If something is complex you must perform some spot inspections especially early in the project

Rule #2 - Don't get involved in hotels, time shares, or condo projects.  All parties are low bid and thus no one is doing their job completely.  This includes the architects, the engineers, the contractor, his subs, etc...  Lawsuits always are the result.  I knew an engineer in Florida who was doing timeshares and hotels for less than $8000.  I saw one up in lake city that didn't even have a structural engineer.  Needless to say the trusses are tied to the light gage curtain walls but the walls are only anchored with a few tapcons.  

Rule #3 - Place a note on your plans that you were perform period observations.....but inspections are not your responsibility etc, etc...

Rule #4 - Make sure you have insurance

Rule #5 - Stay away from the cheap people.   

Rule #6 -  Start spreading the word around on bad engineers and inspectors.  Don't be shy.  For years I would stay out of that sort of thing.  But there are too many firms doing really bad work.  Don't be afraid to call them out.  I had an architect once who gave me some load tables for some SIPS panels.  I saw who the engineer was and told the architect we had better take them with a grain of salt.  Sure enough about a month later he was written up yet again by the board of engineers.

Rule #7 - You do know that most truss engineers are plan stamping.  If you see anything that doesn't jive with your plans reject them.  Reject them over and over again until you get the truss engineer to actually look at your plans.  Most of the time they seal those plans and they've never even seen the contract drawings or even the required loads.  

Rule #8 -  Even the contractors that seem to care, or have a good reputation, even the ones that go to church really only care about the budget, the schedule, and the finish.  Sure they don't want it to fall down right away.  But unless they've seen damage from the eye of the hurricane trying to explain to them the wind load path will cause their eyes to glaze over and their hands to guard their wallets.  

Rule #9 - Consider working for the city or state so that you you can make and engineer's salary, sleep and night, get 8 weeks vacation a year, every holiday under the sun, and a big fat pension.  Oh yeah and you won't have to do anything.   

Rule #10 -  In this slow economy contractors want to build even faster than before.  All projects are now fast track.  Fast Track means we are going to build so fast that nobody can keep up with all the mistakes we are going to make.

Rule # 11 - Masons these days equals person that not even Walmart wants to hire.  This design all walls with bars in the center of the cells.  Anything else will be much too difficult for them to do.  Trust me they won't get it right and they will exhaust any inspector who tries to get them to do it right.  

Rule #11 - Simcon tilt-wall will put the wrong size chairs in their tilt wall panels every time.  In fact they will ship only one size chair regardless of how many panel thicknesses you have on a project.  

In general I don't like to tattle tale, but its just gotten to be too hard to stomach the mess we call construction.  I've always felt like if I am going to do something might as well do it right.  It doesn't take that much longer.  I just can't understand why people don't take pride in their work anymore.  Perhaps its always been this way.  But it seems like its harder and harder to find accurate plans and drawings.  Construction is even worse.   For all the advances we've made in computers, CAD, codes, and over all knowledge its being offset by poor workmanship.  

Sorry I needed to rant a bit.

 

John Southard, M.S., P.E.
http://www.pdhlibrary.com

RE: "Doomed" Las Vegas Tower - Structural Blunders

West coast structural design firms have to play a greater leadership role in providing quality assurance oversight during the construction phase. Who would comprehend the structural drawings better than personnel from the firm that designed the structure?

In my opinion, periodic structural observations (which can only be performed by an RDP) probably would not have been sufficient to catch a major blunder like this. I am almost certain if a PE from the firm had served as a resident special inspector, the non-conforming items would have been detected early on.

One thing many may not recognize is that structural engineers in the west coast are not permitted to perform special inspections (which include rebar inspections) unless they are ICC certified inspectors. Very few SEs/PEs bother to get certified and hence rarely offer special inspection services.

On the east coast, many jurisdictions permit PEs and RAs to perform special inspections without the need for certification. So it is not uncommon to come across solo design engineers on the east coast who also perform special inspections on their projects. I wonder who contractor personnel would pay more attention to when a non-conforming item is pointed out, a certified special inspector or the PE who was responsible for the design?

Clark County NV has one of the best special inspection programs in the country. Coupled with a powerful quality management system with well thought out checks and balances, they have a competent staff of special inspectors who conduct inter-alia, audits on the work of third party special inspectors. Yet still, these non-conforming items were not caught. Makes me wonder whether the county inspectors or third party special inspectors even comprehended certain aspects of the structural drawings on this project. In fact it should not surprise the SE if the typical special inspector does not comprehend complex structural drawings. If the designer determines the drawings will be complex, it is in his/her interest to have several meetings with the special inspector(s) assigned to the project to elucidate the drawings, particularly clarification of complex details.

In some building codes, the responsibility for approving the special inspector lies with the SEOR. LA City BC and NYC BC come to mind. I think this is a good idea. Not sure whether the SEOR approved the inspectors on this project.

I may have zoomed past it in reading (read it twice)...but does anyone know how the problems were first detected?
 

RE: "Doomed" Las Vegas Tower - Structural Blunders

The problems with the reinforcement placement were first discovered during a walk-through, possibly the first one, by a Halcrow engineer.  Based on what he saw, further investigations determined that the defects were widespread.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Thanks hokie66.

RE: "Doomed" Las Vegas Tower - Structural Blunders

Ha!  Rule #9 by Southard2 caused me to laugh.

RE: "Doomed" Las Vegas Tower - Structural Blunders

We had some disastrous failures about thirty years ago, three that come to mind, Willow Island, Kemper Arena and the Hyatt Regency.

There was a push to change state laws nationwide to force EOR control at all stages of design and construction. The construction lobby went to work and since there were no more disasters for a while, it was quietly dropped.

http://en.wikipedia.org/wiki/Willow_Island_disaster

http://en.wikipedia.org/wiki/Kemper_Arena

http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

Oh I forgot one, the Hartford center.

http://en.wikipedia.org/wiki/XL_Center

At the time, I worked for the engineers/CMs for the work at Willow Island (Pleasants Power Station) except that the cooling tower was a separate contract, not included in our work. I had worked on the design of Pleasants Power Station there for several years.

ps. What would you think of a law that required EOR participation/approval though all stages of the work? I see some of us wrongly interfering with means and methods.

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: "Doomed" Las Vegas Tower - Structural Blunders

>>What would you think of a law that required EOR participation/approval though all stages of the work?<<

Isambard Kingdom Brunel would approve.  
He'd probably demand it. ... and get it.



 

Mike Halloran
Pembroke Pines, FL, USA

RE: "Doomed" Las Vegas Tower - Structural Blunders

RFreund -

In regards to your question about pencil sharpening, I think it is difficult to say.  I have worked on several high rises.  In my experience, it is often the case that significant structural design work is done concurrently with ongoing architectural design.  In this way, initial structural designs are developed and refined, over multiple iterations into the final building.  Ideally, the initial structural design will be conservative, and the architectural revisions small enough that the final design is efficient, but not necessarily pushing the absolute limit.  However in some cases, large or unanticipated architectural revisions will require the design to be pushed to its limits.  I would not call the design unsafe, but in a case like this, there wouldn't be much wiggle room, if it was already designed with the sharpest pencil.

To give an example, things like column layouts and slab thickness may be set fairly early on, and the design and cost implications of increasing the slab thickness, by even as little as 1/2", on 40+ floor slabs, will make an engineer more likely to look to up the reinforcing to its limits.  

Another example, changing a single beam W18x35 to W18x40 on a one story project normally is of little concern.  However, if you change 10 such beams, on 40 floors, you've changed 400 beams, and the cost increase is significant enough, that you might be willing to accept the W18x35 designed right up to its allowable limit.

RE: "Doomed" Las Vegas Tower - Structural Blunders

@RFreund and IsaacStructural, much depends on the contract details. If a price per pound is in for changes to the original Contract Documents, then it pays to sharpen the pencil, but if the detailing has started, the cost of drawing changes, revised mill orders etc. may offset any gains.  

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: "Doomed" Las Vegas Tower - Structural Blunders

John,
I have been an engineer in Florida my whole 13 year career and don't disagree with any one of your rules.

I love doing engineering and being a structural engineer, but the business side of things, and the construction admin portion of the projects will make you question yourself why you do this sometimes... But hang in there, you sound like one of the good ones.

And usually I only stop in Lake City for gas or food but I will steer clear of any hotels.

It'd also be nice if the FBPE would do more than have a hearing and then make a guy take a class and pay a $1000 fine.

And to become a threshold inspector in Florida you have to work under one for 3 years (in addition to having your PE license). I would get my license and do this kind of work if those rules were different, and I think I'd be good at it. I sure would bust some balls. Maybe they should offer a class or something. I have to think a lot of engineers are just getting other engineers to fill out their paperwork, wink wink...

RE: "Doomed" Las Vegas Tower - Structural Blunders

Quote:

Rule # 11 - Masons these days equals person that not even Walmart wants to hire.  This design all walls with bars in the center of the cells.  Anything else will be much too difficult for them to do.  Trust me they won't get it right and they will exhaust any inspector who tries to get them to do it right.

Sad, but true.
 

RE: "Doomed" Las Vegas Tower - Structural Blunders

I'm sure I could find the link for this, but until then you'll have to trust me:
In Arizona, one of the skills they teach in prison is blocklaying.
I mean, I like everyone to get a second chance, but doesn't that tell you something?

RE: "Doomed" Las Vegas Tower - Structural Blunders

I am a bit more cynical.  If you want them in one face, but design with all the bars in the centre, they'll put them in the wrong face.

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