"Required" Calculations

[PMR06]

Many forums have come up lately regarding "requiring" calculations, that I have some related general questions to pose:

Who pays for the preparation of calculations? Who pays for the time it takes to review & respond to review comments of those calculations?

Does the reviewer of submitted calculations take on some liability?

Why do ASCE 7 and model building codes not clearly define the extent of calculations?

When did having a PE license lose it's credibility to back up a design that now calculations are "required"?

 

[JAE]

Here are two threads that discussed this fully some time ago.
But there’s always room for more discussion here.

thread507-89434

thread507-141744

 

[PMR06]

JAE, thanks for the links. I tried searching for just such forums, but this site's search function is terrible. You and others have already voiced exactly my concerns. I too would like to hear comments from people who may not have read or posted to those forums.

 

[JAE]

You can use the Google search to the right instead of the in-house Eng-Tips search. The in-house search, I believe, is getting worked on and improved in the near future.

 

[Atomic25]

When did the PE license lose its credibility? I honestly never thought it did have any credibility. Lets face it, just passing 1 multiple choice exam is no reason to think anyone is a good engineer. It only means the person knew enough at the time of the exam to get enough questions right.

Pretty sure the plan reviewers in California take on responsibility and are competent enough to review your calcs.

Defending your design is always paid by the firm providing the drawings.

 

[csd72]

The finished product is a building, not a set of calculations.

 

[cap4000]

Check out this link for some ASCE clarification.

http://www.seaoc.org/bluebook/sample_pdfs/201010Earthquake_smpl2.pdf

 

[kelowna]

I do not have a problem with calculations being asked.

I get asked for them all the time by the Owner's Engineer and I ask for them to the subcontractors when I have any doubt or concern.

Nothing personal. Every engineer should be prepared to produce and defend his/her work. I work on an indsutry where a mistake can cost a lot of money, but more importantly cost lives. Submission of calcs is one of the checks and balances required.

The collapse of the Second Narrows Bridge in Vancouver (1958) was traced to a temporary support calculation. The young engineer calculating the support took the sectional area of an I beam for the shear calculation instead of the web's area. Simple mistake, could happen to anybody,... 27 people died, including the young engineer that made the mistake and the senior engineer that checked his calc and missed the mistake.

The Royal Commision of Inquiry finished the report into the collapse by saying:
"The lessons of this disaster may perhaps be summarized by pointing out that small and simple mistakes can lead to big catastrophes and that no opportunity should be missed in arranging for the check and re-check of the design and detailing of an engineering structure for its ability to perform its intended duty"

Not only I do not mind somebody else checking my calculations, I like it, and any young engineer that starts working with me has to read the Royal Commision Report. It drives the message home.

 

[PMR06]

Atomic25, I think JAE said it best in one of the other forums that code reviewers should be reviewing the PLANS for CODE COMPLIANCE. That, if anything, is what their training is in.

I'll admit I do not entirely know what education is required for a code reviewer. I suspect it is not even close to a 4 year engineering degree, 4 years of training, a list of references that can attest to the engineering skill, and then passing the test. I suspect it is nothing more than a high school diploma and passing a drug test. I could be trivializing the code reviewer's role though, as you have trivialized the PE exam.

 

[nutte]

Kelowna, I think there are two separate issues here.

The first: As the engineer of record for a building, my seal is sufficient to certify that the building meets applicable building codes, has been designed properly, etc. I would take exception to a building code compliance official asking for calculations, as my seal states that I am qualified and that this building is adequately designed. If that is not sufficient, then we need to reconsider why we even license engineers.

The second: If a subcontractor designs a component of a building, it really depends on what the contract documents state. I would say they often require sealed calculations, and in this case, I would expect the subcontractor's engineer to submit calculations willingly. I have done this myself when acting in this role. The difference is that the engineer of record is interpreting the building code requirements to design the building, and his seal states that he is qualified to perform that task. The subcontractor is not interpreting the building code, but rather the drawings prepared by the EOR, to design his component. Thus, it is critical for the EOR to verify the calcualtions to ensure that the design intent was met. The seal on the calculations certifies that the calculations (number crunching) are correct, and the EOR's review of them will determine if the proper design requirements have been followed.

I would expect sealed calculations for components like wood trusses, light gage assemblies, steel connections, erection analyses, etc. The accident you describe sounds like it had to do with erection, which would fall into the second scenario above.

 

[nutte]

The finished product is a building, not a set of calculations.

I would disagree with this, only to clarify what my finished product is. As an engineer, my finished product is a set of design documents. The building is constructed by craftsmen who may or may not build it in accordance with the design documents. My services were to provide a design for the building, not to construct it.

We shouldn't trivialize the production of the design drawings. Indeed, they are important, or else the code compliance officials wouldn't care anything about seeing them. In the same regard, designs and calculations prepared by subcontractors are important as tools for the other parties involved to use to construct the building.

 

[csd72]

PMR06

I 100% agree that it should be the drawings that are checked not the calculations.

The calculations are usually done before the drawings, so there may be some things changed on drawings that were on the safe side, but were not reflected in the calculations.

The quickest way to check a design is usually by independent calculation. The one exception being where extensive computer analysis is required.

The calculations may contain logical errors. If these errors seemed correct to the original engineer then the error may also seem correct to a checking engineer. Independent calculations are not susceptable to following the same errors in logic.

In the uk, local authorities emply junior engineers to check calculations. This means that if you dont dot your i and cross your t on all calcs there will be extensive queries. The calcs may be correct, but the inexperienced checker may no understand them.

csd

 

[Dinosaur]

I have been asked many times to review other's work. I hope that after seeing some of the mistakes I have caught, you would not think this kind of review is unwarrented.

 

[connect2]

Wow, not much has changed, there's also a thread currently going on called 'Shop Drawing Review', just down a bit, same thing. If calc's are requested or a requirement of the Building Official, we do, otherwise we don't. We can't stop others from reviewing our design drawings, its a free world they can do so if they wish.

 

[DonPhillips]

PMR06

Plan reviewers for other than 1- and 2-Family residential generally have to be licensed engineers or architects.


Don Phillips

http://worthingtonengineering.com

 

[PMR06]

DonPhillips, I stand corrected then. My admittedly unfair generalization was due to one reviewer of a project of ours that I know was not a licensed engineer. We spent many hours preparing a letter and supplemental calcs in response to his numerous comments and questions. In the end, not a single change was made to the drawings, nothing. We nearly lost a client though because we were insistent on charging for the review response time.

My boss has a saying: "It takes 2 seconds to say the sky is falling; it takes 2 hours to prove it is not". It is now in our contract that [paraphrasing] unless there was a gross error on our part, we will charge for excessive time needed in response of third party reviews.

 

[DonPhillips]

I have had many similar experiences and I typically ask for the code reference to see if the comment is real or if it is that person's "good idea."

This is especially true of building inspectors being plan reviewers of 1- and 2-family residences, where many years of constructon experience substitutes for reading and interpreting codes. Sometimes, the person is misinterpreting a code provision, or remembering something from years past but twisting it based on too much time passing since reading the code.

So I can understand your frustration. Unless the reviewer is out in left field, I seldom charge for responding to correction letters since I feel I had a duty to meet the code.

I charged a builder once for listening to the building inspector's "comment" that my beam on an addition was overdesigned (I specified steel to save him money) and he wanted to do 2x's because the inspector said it would work. He paid the bill for the redesign (using select structural lumber) but I have not gotten any work from him since.


Don Phillips

http://worthingtonengineering.com

 

[JStephen]

It has been my impression that in most cases where I had to submit calculations for a job, that whoever reviewed the calculations knew nothing about the topic other than what they learned from my calculations. This tends to make the whole issue appear as either a box-checking request, or a keep-it-in-case-we-sue-'em-later request.

I have learned through the years that when calculations are requested, the more detailed and thorough that they are, the more there is to nitpick. So I ususally submit calculations on major items only and everyone seems happy with that.

I have learned through the years that anything that is engineered can be engineered some more, and there is no end of calculation that could be done for any given project. Lean a 2x4 against a wall and NASA could spend the next century analyzing it if they so chose. Part of engineering judgment is knowing what to analyze and what not to analyze and what degree of complexity is appropriate for different situations.

 

[csd72]

As my first boss once said, it is not worth spending 10 hours at $75 an hour just to save the client $500 worth of steel.

All buildings can be designed more efficiently and in a perfect world they would be. But a perfect design also requires perfect construction, any misalignment of columns e.t.c. and the design would not work.

The other problem with checkers is that they have to find something wrong, the client would not feel they are doing their job if they didnt.

That said, I have carried out checks on dozens of jobs, some with very experienced designers, and I always find something. With the more experienced designers the errors tend to be smaller. But I dont check calculations, I check drawings, and only refer to calculations when I am not sure how something has been made to work.

csd

 

[bjb]

Atomic 25,

I agree that passing one of the PE exams does not mean that you are a good engineer. However, when you look at the pass rates for the Struct 1 test at the NCEES site, I wouldn't call passing it trivial either.