quonset arch section properties 1

[civilsid]

I was approached by a client to design a foundation for his U.S. Buildings quonset hut shaped garage. Our local municipality requires structural calculations in addition to the plans. U.S. Buildings told me it would be an additional $2,000 for the calcs.

Of course this is completely outrageous. This is an off-the-shelf design and not custom in any way. While I do not get into structural design very much, I am sure that if I procure the correct manual(s), I will get all the data I need to provide to the local building authorities.

My question is of course the best resource for arch data for steel buildings. I looked in "Designing Steel Structures" by Cooper but there is just one page dedicated to arches. I also have "Metal Building Systems" by Newman but no help there either.

Am I going to find the data I need in the AISC steel manual? Is this a "typical" section? I don't even know what to call the thing except a corrugated arch.

Please help!

 

[cancmm]

If you're designing the foundation, which I'm assuming is a shallow footing, then you will not likely need a material spec such as AISC. Calculate your design forces in accordance with the applicable force combinations (IBC, ASCE). All you need is the deadload and the reactions due to wind. Don't get too detailed and make conservative assumptions if you wish to keep this simple/cheap. Building officials are usually ok with this as long as you justify why your methodology is conservative. Your footing design will simply be a relation to soil bearing pressure. Load is generally concentric on the footing. Lateral forces resulting from arch spreading are usually negated through cross-ties located under the floor of the structure.

This is beyond what you'll need, but the applicable guideline on this type of building would be in regards to cold-formed steel structures. You won't find corrugated sections in the black or green AISC manuals.

 

[cancmm]

Forgot to mention that if you are looking to provide structural calcs for the building itself, then there is no way that you will be able to do this for $2000. The time it takes to design this thing, including all the connections, bolt arrangements, etc. make this a futile effort.

Additionally, are you signing/sealing the design and calculations for a proprietary system such as this??? I'd hope not.

 

[civilsid]

Yes, I am OK with the foundation / footing design. The building department wants the calcs on the building itself: "Two sets of plans and two sets of calculations for metal buildings shall be submitted, wet stamped by an engineer registered in Arizona".

The part that annoys me is that the building manufacturer will not release the calculations without paying a lot more money. If I were asked to provide calculations explaining why my design was acceptable on any of my projects, I certainly would not charge thousands of dollars for it.

Isn't there some sort of ethical obligation to provide backup data and calcs if someone asks you why you said a certain design was safe and allowable? I'm sure the engineer that stamped the building plans did do the required mathematical calculations or at least pushed a few keystrokes on a computer somewhere so some computer could tell him it was OK... he couldn't (or shouldn't) possibly just say "I dunno, looks good to me!" without doing the math behind the design.

When I called the building manufacturer, they would not let me talk to the engineer that stamped the plans. They act like they have to sit down and do all of the calcs from scratch every time someone new asks for it. This building is a stock item. I'm sure all the calculations are in a little binder. There is no way they can justify an extra $2,000 for the calcs on a stock item. I know I am repeating myself but I am floored by what is nothing more than highway robbery.

I have the digital canal suite including general section properties and versa frame but I'm not that well versed and this is an arch, not just a beam or column.

 

[cancmm]

I believe there are jurisdictions where, depending on usage, the actual calculations are not required.

And if/when you figure this out, your submittal would have the drawings stamped by their engineer while the calcs would be stamped by you? Who then takes liability? My guess is you.

Say you knew exactly what you were doing and it was going to take you 8 hours to perform the design and 4 hours to put the calculation package together. Assume an rate in the $130 range and you're already over $1500. What are you trying to save?

Is there another vendor who can offer a similar product at a more reasonable cost, calcs included?

 

[msquared48]

I think the owner would have been given a set of the calcs when he purchased the building. If not, and US Buildings has to have done business in AZ in the past with the full knowledge that this is a requirement, why was the owner not informed of the additional cost? The metal building company I worked with for over 20 years ALWAYS furnished a set of calculations, required or not.

This seems wront to me, and I would consider making a formal complaint with the State Attorney General Consumer Affairs Division, citing misleading and deceptive business practices if appropriate. It's the old game of hidden costs and not finding out what they are unless you have the knowledge to ask the right questions.

Kinda makes them more competitive too, doesn't it. Very convenient. if they keep doing this in today's market, they will not be in business much longer, trust me.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[IDS]

Do they need calculations for the structure or calculations for the foundations you are designing? If the latter you just need the supplier to give you design foundation loads, and I agree that there should be no additional charge for that. If the former then the owner should get the calculations from the supplier; there is no reason why you should be involved.

A charge of an additional $2000 for design calculations for a propriatary product sounds quite reasonable to me. Why do people think they should give their knowledge away for nothing?

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[Lion06]

I may be in the minority here, but I'm ok with charging $2000 for the calcs.

I'm very new at this game, but not a single project I've been involved in to this point in my career has had calculations as part of the "deliverables". The final product that we provide to the client is a good set of drawings/specifications, calculations are just the tools that we use to develop our drawings (the deliverables).

That being said, if a building code official needs to see calcs, then they should be provided to the official for free (again, in my green opinion). Additionally, any element that is not designed by them needs to have loads listed on the drawings otherwise they're not providing complete documents or a complete structure.

I know if I needed to get a set of calcs for an entire project together and put them all in some coherent order for someone who didn't do them to make sense of everything, it might take quite a while.

 

[Lion06]

Additionally, $2000 is nothing compared to the cost of construction. Would anyone even bat an eye if the concrete sub came in at $72000 instead of $70000?

I read a pretty good article about a year ago or so from STRUCTURE magazine. It was a principal of some firm talking about how we should be seriously trying to raise engineering salaries (on the order of 20% - 30%) over the next 5 years. He made the argument that a typical structural engineer's cost is on the order of 2% - 3% of construction cost. If that increased by 20%, we're at 2.4% - 3.6%............. still a drop in the bucket.

 

[paddingtongreen]

Much depends on the type of work and on the particular state. I've worked on many jobs where the calcs are reviewed by the N J Department of Community Affairs, for example.

http://www.state.nj.us/njbusiness/forms/pr_app_guide_2009.pdf

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

 

[msquared48]

Sorry, but I cannot agree here. I can understand if they did not include the calcs to lower the price for the owner, thinking they were not required by the local jurisdiction. But nothing has been stated by the OP to verify that scenario.

What I wonder is how, unless it is a cookbook solution, are you ever going to design any foundation without the foundation reactions, which, just happen to be within the calculations?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[civilsid]

A couple things-

I spoke with a contractor friend last night and he explained that he has heard this same story many times. The company selling the buildings provides a low-ball number and then screws the buyer at every turn and the buyer has no choice but to pay it.

Also, this is a residential project. Building is 34'-5" x 64'-5" out/out. The buyer had no idea and thought he could buy a building, get a permit, and erect it himself which is "what the salesman on the phone said".

I guess I never will find out how to calculate a currugated arch which I would still find interesting; though I will not be attemtping to re-invent the wheel and do all the calculations required of this steel building.

And finally the ethics issue. In order to put out a final product or planset, the engineer has to do the calculations. If the client wants it, why not give it to him? He is the one putting food on your table. If it takes a lot of administrative effort to compile it then of course charge him for the collating, binding, etc. which could be a couple hundred dollars but the client paid you to do a job and if he asks you to "show your work" like your high school math teacher did, then why would you ever piss him off and try to squeeze him for more money? To make matters even more unbearable in this particular instance, we are talking about a stock item- the engineering is done once and many instances of that same item are sold over and over. Now I understand that each time the engineer stamps a drawing, he does have the liability for it which he should be compensated for. However, he does not take on any more liability for having provided the calculations behind the final design. For all I know, the engineer may not be getting compensated at all anyways. I simply know that the building salesman have priced the calcs as $2,000. Since I was not allowed to talk to the engineer, he may have no idea the sales guy is doing this at all. Maybe I will call the board of technical registration (our governing body in AZ) and get the contact information for the engineer of record and call him direct.

 

[JedClampett]

I could see why someone wants to charge $2000 for a set of calculations. Sometimes the calculations are done by technicians or non licensed engineers. There is an expense to have the engineer of record "...make them his/her own." Or the engineer of record might have done calculations, but they're not presentable. To organize them and reproduce them creates an expense.
When you buy a proprietary building like a Quonset hut, you've compromised some design flexibility to save money. You want to change the building loads or function? Too bad! Why do you think they're so cheap? And as far as an ethical responsibility, they don't care. Go sue them. There's always more customers ringing the phone to get the cheapest piece of junk.
We engineers who provide calculations for every project and go that extra mile can always be undercut on price. The good news is when the building starts to shake, rattle and roll, the original designer is nowhere to be found and we get the business.

 

[paddingtongreen]

Consider also that the engineer who performed the design work probably was not registered in every state. Each additional state needs a new seal, involving time and expense.

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

 

[apsix]

Obviously your client is at fault, he should have told the manufacturer of his reckless intent to erect and use the building!

Assuming the manufacturer claimed that it

 

[apsix]

Obviously your client is at fault, he should have told the manufacturer of his reckless intent to erect and use the building!

 

[CTW]

True that the client is at fault but his intent does not seem to be reckless. These buildings are advertised as "do it yourself" construction. If someone is capable of erecting that type of building, it's certainly a cheap way to get additional storage. But his fault comes from not knowing the requirements for permitting. Most homeowners know they should pull a permit for their work. But most don't know anything more about the process of permitting. So the client was unaware of what was required to obtain a permit for this building. The disconnect here is that most people don't know that they need to research the permitting requirements in their area, call the building department to ask or hire an engineer from the start. This stuff isn't advertised by the local jurisdiction.