"Required" Calculations
"Required" Calculations
(OP)
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"?
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"?






RE: "Required" Calculations
But there’s always room for more discussion here.
thread507-89434: Calculations: Personal Tool or Public Record
thread507-141744: Submitting calculations
RE: "Required" Calculations
RE: "Required" Calculations
RE: "Required" Calculations
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.
RE: "Required" Calculations
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RE: "Required" Calculations
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.
RE: "Required" Calculations
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.
RE: "Required" Calculations
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.
RE: "Required" Calculations
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.
RE: "Required" Calculations
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
RE: "Required" Calculations
RE: "Required" Calculations
RE: "Required" Calculations
Plan reviewers for other than 1- and 2-Family residential generally have to be licensed engineers or architects.
Don Phillips
http://worthingtonengineering.com
RE: "Required" Calculations
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.
RE: "Required" Calculations
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
RE: "Required" Calculations
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.
RE: "Required" Calculations
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
RE: "Required" Calculations
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.
RE: "Required" Calculations
If an owner does not have knowlegible engineers on staff, they can hire an independent engineer to review calculations for critical items.
Or, if no one reviews - just seeing that calculations have been done and checked is good due diligence.
RE: "Required" Calculations
Building officials should review calculations AND drawings for code compliance PLUS any life/safety issues not addressed in the code. Requiring calcs for details shown on the drawings without calculations is perfectly justified, in my opinion. But asking for detailed calculations that take a lot of time/money, which in the end do not change the design shown the first time, is a bit out of line.
RE: "Required" Calculations
I disagree the building official (BO) should review calculations if designed by a registered design professional, the drawings are sealed and contain all the information required by the code. Otherwise this would be akin to a design professional getting involved in means and methods of a contractor. The design professional has to take responsibility for the design and if the BO misses something in the calculations, may take on some of that responsibility.
Now for 1- and 2-family residential where most jurisdictions except these from seal requirements, I would typically want the calculations to review. But we are typically talking about joist, rafter, and beam spans, that are relatively straight forward.
Don Phillips
http://worthingtonengineering.com
RE: "Required" Calculations
Forgot another thing. Building Officials do not have the authority to enforce life/safety issues not addressed in the code. If it is not regulated, they cannot enforce it. Similarly, they cannot grant variences either.
Don Phillips
http://worthingtonengineering.com
RE: "Required" Calculations
If you know Calculations are going to be required it is simple to keep a project folder during design and add the calc’s as you go. This should be done with every project regardless if the code official wants a copy.
In office, we have every single project reviewed (including calculations) before the plans are sealed and leave the building. Since we use many in-house spreadsheets for our calculations we also include a word document that explain how the program works and shows the hidden calc’s not shown on the output sheet. This also allows you to update the program when the Code changes every three years.
As a reviewer for several different Cities we require calculations to be submitted with the drawings. It is amazing how many mistakes I see, especially in Wind and Seismic Calculations. I seriously think that many engineers have not realized that the ASCE 7 is updated every 3 years. We require IBC 2006 in our area, last week I had a design come through based on the 1996 BOCA code. Yet they used an older version of Enercalc that is based on the 1997 UBC code. I would estimate that a quarter of the buildings we review have no lateral design calculations. Some Engineers have called our office and asked what we mean by lateral calculations, do people really not know? Just because an engineer has signed and sealed the plans doesn’t mean that errors don’t slip through.
I photo copy mistakes we see and put them in a book, one to teach our new engineers what not to do. Maybe one day I will travel the circuit of overpriced Professional conventions and speak about them. At least it will keep you awake.
RE: "Required" Calculations
That being said, a prudent EOR should be reviewing calcs for anything that is within the scope of his work that was farmed out as "performance spec" (e.g. metal studs, stairs, etc..). Again, the liability ultimately rests with the EOR and the defense of, "well a different PE designed it, I only approved it" isn't going to cut it.
The building inspector's office isn't taking on any liability by reviewing calcs.
I guess if the calcs were reviewed in a fashion so as to make sure no grossly large errors were made would be more appropriate than nit-picking that the CMU back-up should be 90plf not the 88plf that the EOR state because he rounded a little in an earlier step. That just seems a bit much to me.
If there is no lateral system as mentioned above, that is certainly cause for concern. If you disagree with a load by 2%, let's not forget the factors of safety inherently involved in any structural design calculation (some of which are meant to directly account for things like that).
RE: "Required" Calculations
I agree that IF "designed by a registered design professional, the drawings are sealed and contain all the information required by the code", there is absolutely no need for a Building Official. However, someone has verify that the drawings indeed "contain all the information required by the code". Should every project be peer-reviewed?
Let's presume that the drawings are 100% code compliant and it is in the hands of a contractor. Does the EOR perform site visits at critical phases of the project to ensure that contractor is doing the right thing?
In this profession, we need proper amounts of checks and balances by all parties involved.
Typically building inspectors are not licensed engineers. If they do not possess a PE license, they are not qualified to review calculations by EOR.
RE: "Required" Calculations