CONSTRUCTION DOCUMENTS FORMAT 3

[MikeMech]

I have been asked to supply engineering structural calculations to an architect for a small project.

Is there a standard for the content and style of my submitted calculations? As I do most of the actual calculations via computer programs, do I just give assumed loadings IAW IBC and resultant safety factors, or what?

An example would be ideal.

Please help, thanks in advance!

Mike

 

[austim]

Mike,

Your query worries me somewhat. It gives rise to some obvious questions -

Are you really properly qualified (by training and by experience) to be doing these calculations ?

Are you legally permitted to do so ?

Do you have appropriate liability cover (ie cover that will prtect you and your client in the event of a subsequently identified defect in your design)? (I have been practising as a structural engineer for more than 40 years, but am not permitted to do structural design for buildings in my own state of residence because of the type of professional indemnity cover that I have).

You are only referring to calculations - if that just means sizing the structural members, who is going to detail the structural connections? (If the architect or a fabricator is going to do that, then I recommend that you have a talk to your insurers about the whole business).

If you were to send me a document for approval which simply listed the input loads and computed safety factors you would get it back by return post, with a demand for a proper set of calculations.

 

[Ron]

I concur with austim's concerns as well.

Additionally, it sounds as though you might be doing what is known as "delegate" engineering work. That is when the Structural Engineer of Record (SER)delegates the work of some component or part to a producer or other engineer to prove compliance with the design intent. If this is the case, then I offer the following:

Your calculations should be detailed enough so that the SER can adequately review your approach and results. This should include your pre-processing assumptions of load case and variables, consistent with the code requirements.

Both your input variables and your output, along with any post-processing analysis should be included.

You should sign and seal any computations and signify that your analytical program has been validated by comparable hand calculations.

If you can't do at least these items, give it to someone else.

Ron

 

[haynewp]

Coincidentally, where I live, architects do calcs, develop, and stamp structural drawings all the time and they have no idea what they are doing. They seem to understand gravity loads but not lateral systems. And this is recognized by the state as being acceptable. The structural drawings never actually get looked at by a structural engineer. I couldn't believe it when I found out.

 

[LPPE]

Remind me not to live where heynewp lives.

 

[bylar]

pylko
I lived in Florida for 30 years and Architects did a lot of the structural drawings with very little structural knowledge but a structural eng. had to be extreemly careful not to encroach on anything architectural.

They have a better lobby!

 

[haynewp]

I called the California state board and they said the same thing is accepted and happens. In CA, architects have the same ability as a PE does. The only difference comes with hospitals and schools which then require an SE stamp. Architects are left with deciding at what point they feel they need to hire a structural engineer.

It seems kind of strange to me that engineering organizations are pushing for a masters before eligible for a PE,(I'm not disagreeing), but let this go by.

 

[JAE]

We're getting a little off-topic from MikeMech's question - but here's another slant on calcs.

When I was "growing up" as an engineer, my mentors always refused to submit any calculations to anyone. Their reasoning was that the calculations are a personal tool of the engineer....they are not, and have never been, the service for which they were contracted. What an engineer "sells" to a client is the service of designing a structure that can be bid, built, and is safe. The calcs are no different than a calculator....just a tool.

And the calcs are subject to extreme ranges of interpretation. Different engineers have different styles of writing, recording, abbreviating, etc. This concept can even be taken to the drawings themselves. The drawings are the communication tool that the engineer uses to provide his service....the drawings themselves are not the service.

All that said, today, more and more owners are requiring submitted calcs, specs, drawings, etc. with our seal on it as though they are BUYING our drawings. We, as engineers, become providers of a commodity, not a profession.

(vent vent vent vent) sorry.

 

[Ron]

JAE...You're right about our work product. We shouldn't put it out for everyone to shoot at (wrongly, of course!). Under the delegate engineer process, the function of supplying calcs. is to allow the SER the opportunity to check design intent. It is not intended for layman consumption.

 

[Qshake]

Off topic yes, but this business of architects having more latitude over structural engineering rather than vice versa really burns me up. At present, Illinois is no different than those other states requiring a SE License. I couldn't believe my eyes when I read that "after" being licensed and receiving my package of rules. I say "at present" as I hope it changes soon.

 

[MikeMech]

Thanks for the timely input everyone. I have decided to withdraw from the project and recommended someone else who has many years experience dealing with architects in structural matters. After consideration, I felt that while I may be competent to perform a strength analysis on the structure (a large canopy sort of thing) and can read and comprehend the IBC and related codes, I don't have enough experience with this type of structural analysis to rely solely on my own judgement.

I'm sort of an engineering jack of all trades, I own my own business and have 10 yrs experience in design of fabrications, castings, machinery, manufacturing processes, etc. I have a PE, but find it mostly useless except as a suffix to my name when writing important documents for customers.

JAE brings up some interesting topics. At what point do you assume the reader of your calcs knows what you're talking about? On one extreme you can simply state your assumptions and state whether the item under scrutiny will fail, referencing what codes you used if applicable. On the other extreme, you can write a report and show all of your FBD's for each member, explain all notation, show all steps in each calc, show EVERY calc, show load diagrams, show every safety factor for each member, etc etc. A non-engineer would have to take you on faith in either extreme, although he would be more impressed by the latter. To another engineer, the one page report is useless and the 100 page report is tedious and unnecessary.

A philisophical question: As a consulting engineer, is it best for one to sell one's opinion, ("This will/won't work&quot or the PROOF of one's opinion ("This will/won't work, and here is proof WHY: ...&quot? Is one opinion worth more that the other? Why? The proof of an engineer's opinion is usually greek to the customer, unless he has a another competent engineer available to him, in which case why has he hired you? On the other hand, opinions without backing are usually suspect. Catch-22?

I always thought of myself as selling knowledge, not drawings or calculations or even products. It's the knowledge of how to do something better/faster/correctly that is worth money. The knowledge benefit can be transfered to the customer in many ways, by teaching, by drawings, by a turnkey product, or by simply saying, "Do it this way and it will work. I guarantee it. That'll be $1,000." It's the knowledge that makes profit.

My almost-client and his architect were both very vague about what they actually needed from me. I got the feeling that all they wanted was a drawing and some calcs to give to somebody (the local gov. inspector?) and didn't really care what was included, as long as the Powers That Be had them to put in their files. Neither of them had a clue as to the forces involved, and their preliminary structural and foundation designs would have failed catastrophically.

Out of curiosity, once the architect has his calcs and drawings from his engineer, say, for an addition to an existing building, who then approves them? A gov. engineer? The owner? Or does the buck stop, practially speaking, with the engineer who does the calcs? If that's the case, I can imagine a number of structures are built according to simplified calcs done by an architect or in-house inexperienced engineer to lower the cost. Yikes.

Anyway, thanks again for your input.

Best Regards,
Mike

 

[Ron]

Mike...I think you were smart to pass on this one. I've been in similar situations, and even as a practitioner of structural engineering, find it is sometimes difficult to meet the parameters set forth (particularly restictions!).

As Structural Engineers of Record (SER) we have the autonomy to say "This is what it is...you don't need to know "why", that's why you hired me" Though flippant and arrogant, that's really the way we are engaged. Most other professionals (architects, other engineers)don't question this to a great degree. As JAE said, the calcs are just one more tool. They are intended for internal validation. There is nothing that says we have to calculate anything....it is; however, part of the standard of care in our practice so we do it as part of our file documentation. Structural Engineering is, in general, a performance criteria, not a procedural criteria. Our goal is usually to optimize the structural performance, not just follow the credo "When in doubt, make it stout!" That usually separates the men from the boys!

On the other side of that coin, even we, as structural engineers, will write into our specifications for product or "pieces and parts" submittals something to the effect of "This component shall be designed to withstand the loadings required by ASCE 7. Calculations, signed and sealed by a Registered Professional Engineer who professes his practice to be structural engineering, licensed in the state where the project exists, shall be submitted to the SER for review".

Further, some state laws place enough of a statutory obligation on the SER that this becomes necessary. Here is an excerpt from Florida's law on this matter:

61G15-30.005 Request for and Review of Delegated Engineering Documents.
(1) An engineer of record who delegates a portion of his responsibility to a delegated engineer is obligated to
communicate in writing his engineering requirements to the delegated engineer.
(2) An engineer of record who delegates a portion of his design responsibility to a delegated engineer shall require
submission of delegated engineering documents prepared by the delegated engineer and shall review those documents
for compliance with his written engineering requirements and to confirm the following:
(a) That the delegated engineering documents have been prepared by an engineer.
(b) That the delegated engineering documents of the delegated engineer conform with the intent of the engineer of
record and meet the written criteria.
(c) That the effect of the delegated engineer's work on the overall project generally conforms with the intent of the
engineer of record.
Specific Authority 471.033(2), 471.008 FS.
Law Implemented 471.033(1)(g) FS.
History--New 1-26-93, Formerly 21H-30.005.

61G15-30.006 Delegated Engineer's Responsibility.
(1) It is the delegated engineer's responsibility to review the Engineer of Record's written engineering requirements and
authorization for the delegated engineering document to determine the appropriate scope of engineering.
(2) The delegated engineering document shall comply with the written engineering requirements received from the
engineer of record. They shall include the project identification and the criteria used as a basis for its preparation. If a
delegated engineer determines there are details, features or unanticipated project limits which conflict with the written
engineering requirements provided by the engineer of record, the delegated engineer shall timely contact the engineer
of record for resolution of conflicts.
(3) The delegated engineer shall forward the delegated engineering document to the engineer of record for review. All
final delegated engineering documents require the impressed seal and signature of the delegated engineer and include:
(a) Drawings introducing engineering input such as defining the configuration or structural capacity of structural
components and/or their assembly into structural systems.
(b) Calculations.
(c) Computer printouts which are an acceptable substitute for manual calculations provided they are accompanied by
sufficient design assumptions and identified input and output information to permit their proper evaluation. Such
information shall bear the impressed seal and signature of the delegated engineer as an indication that said engineer has
accepted responsibility for the results.
Specific Authority 471.033(2), 471.008 FS.
Law Implemented 471.033(1)(g) FS.
History--New 1-26-93, Formerly 21H-30.006.

Sorry for the long-winded response, but I think one of the great values of Eng-Tips is the discussion process..

Ron

 

[LPPE]

Great discussion and responses, all. In my neck of the woods, residential construction is typically all done by an architect. Signed and sealed. Anything more usually requires an engineers stamp.
I work in an AE firm, and the reason I would not trust an architect signing and sealing CD's is that I often get drawings from the arch's that allow for an 8" beam spanning 80 feet. I mean, c'mon! Dont these guys have a clue as to the limitations of materials, and basic span to depth ratios? And someone stated before, that arch's generally understand gravity loads, but look at you like they just crapped their pants when you mention lateral loads.
I guess its the age old battle between architects and engineers.

 

[MikeMech]

A friend of mine was getting his architectural degree at Washington U. in St. Louis, supposedly a good program. In one of his design classes, the prof had them do a design for a parking garage. One student's design was considered by him to be the "best". It was a steel structure with concrete floors, totally enclosed with glass. No proviisions for ventilation, heat reduction, and an irresistable target for vandals. It would have been a toxic fume filled solar oven. The professor loved it. My friend changed majors shortly afterwards.

On the flip side, I got my BSME at the same university. Good program, except they taught us zero about asthetics and business theory. Just lots of formulae and modeling techniques.

It seems a shame to me that arch. is treated by many schools as art and and engineering as math, and ne'er the twain shall meet. If they had more courses in common, they might be able to work together more easily.