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"Doomed" Las Vegas Tower - Structural Blunders 17
- Thread starter JAE
- Start date
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?
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?
abusementpark
Structural
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.
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
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
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.
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.
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4
- #47
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.
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.
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?
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?
paddingtongreen
Structural
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.
Oh I forgot one, the Hartford 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.
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.
Oh I forgot one, the Hartford 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.
MikeHalloran
Mechanical
>>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
Isambard Kingdom Brunel would approve.
He'd probably demand it. ... and get it.
Mike Halloran
Pembroke Pines, FL, USA
IsaacStructural
Structural
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.
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.
paddingtongreen
Structural
@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.
Michael.
Timing has a lot to do with the outcome of a rain dance.
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...
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...
JedClampett
Structural
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?
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?
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