Communicating structural calculations 13

[spaderess]

There is a disregard for the handicraft of writing and performing legible sequences of calculations in my immediate context. Trying to check or re-use even my own, let alone others, calculations is a pain.

I have been looking into literature or standards in an attempt to better this. Yet, most of the stuff I found is centered on general mathematical writing and therefore not as applicable. The only books I found directly dealing with the specific problems are Robert Motes books The Engineers Word, and The engineers Tables. Standards, on the other hand, seems to be specific to firms and not accesible from the outside. This lack is surprising, coming from an architectural background, where all aspects of drawings are highly standardized.

Therefore, my questions are these.
1. Are there any literature or widely available standards dealing with presentation and/or performing of structural calculations?
2. Do you know of any examples of sets of calculations available, to be used as a best-practices-example?
3. What do you consider to be essential qualities in regards to clarity when checking others calculations?

 

[hokie66]

I will try to address your point 3. Don't just include a bunch of numbers in your calculations, but rather explain them in words. The first step is to define the problem, in words. Then, as you go along, describe what you are doing, and also provide any references you use, such as code provisions, textbook pages, etc. Then, at the end, explain your conclusions, including any engineering judgment calls you make. This all makes following your comps simple, both for you and anyone else.

 

[WARose]

2. Do you know of any examples of sets of calculations available, to be used as a best-practices-example?

I always thought '246 Solved Structural Engineering Problems' (by Buckner) is one of the best presentations I've seen for structural calculations.

Checking an existing structure makes things easier: you can reference the drawing/detail number in your calcs. That's one of the biggest headaches in looking at anyone's calculations for a decent sized project: wondering what they are actually running numbers on.

 

[Shotzie]

Regarding item number 3, I find that putting a cover sheet on my calculations that I can go back and write assumptions on helps. Then the meaning behind the numbers contained within the calculations is more evident. Also, calling off live versus dead loads throughout the calculations (for example) and writing things out in consistent format for repetitive members typically helps.

I agree with hokie66's comments above as well.

WARose, could you post a sample if you have one? I'd be curious to see how Buckner laid out the calculations.

 

[WARose]

WARose, could you post a sample if you have one?

Probably not without breaking copyright laws. PPI use to post a free sample of it on their site.....but I cannot find it over there now.

 

[dik]

WARrose:

if I'm checking another engineers work, I find it much faster to quickly do my own calculations on things that 'just don't look right'. I almost never go through the other engineers calculations... I find it much better not to follow something and maybe get caught up in 'his/her' methodology...

Dik

 

[MotorCity]

If your design involves obscure equations or theories, write out the equation being used and reference supporting documents (white papers, industry publications, etc.) Every one understands that not every design consists of "cookbook calculations" and sometimes we need to venture outside of conventional design. Just save your checker/reviewer the time of a lengthy internet search and let him/her know where you are pulling information from.

 

[drawoh]

spaderess,

If I do calculations that must be submitted to somebody, I use Microsoft Word. My next choice would be LaTeX, but I would have to do that from home.

--
JHG

 

[ash060]

The first step is to define the problem, in words. Then, as you go along, describe what you are doing, and also provide any references you use, such as code provisions, textbook pages, etc. Then, at the end, explain your conclusions, including any engineering judgment calls you make. This all makes following your comps simple, both for you and anyone else.

I do the exact same thing. I write out everything, especially my thought process on why I did what I did, to make sure that the reasoning makes sense. I record important calls or conversations, along with any important references. My calculations are more like a journal of the project than anything else. Helps me a great deal when I am looking back a year later and wondering why I did something that looks ridiculous, I had a reason (whether good or bad, I had one).

Just a string of equations and numbers can be hard to follow real quick.

 

[JAE]

I've seen publications on drawings - but not calculations.
(ACEC put out a document called "A Guideline Addressing Coordination and Completeness of Structural Construction Documents", by the Council of American Structural Engineers (CASE).)

Link HERE

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[KootK]

@JAE: I might need that document. Do you have a copy? Not to share but to speak to. Can you speak to its usefulness?

In addition to what others have said, I have these thoughts to add:

1) It's always hard to review a one off hand calc. For that reason, I feel that it's hugely important to be using the same tools as everyone else in your organization, even if those tools might be inferior to your latest, VBA-packed, Excel Tour de Force.

2) I've been seeing some young guys and gals put together great stuff using MathCAD Express (or something like it) and Bluebeam (or something like it). The math will be easy to read and clips of the architectural elevations and code provisions will be dropped right in there. Slick. No need to sweat units or calculation errors. I find that the most common errors aren't math/code, they're a lack of understanding of what's actually going on and how asituation is typically handled. This set up sort of helps with that.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JAE]

KootK,
We have an older copy. About half of it is a checklist.
It's OK but not sure it tells me anything I didn't already know.

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[IDS]

It's always hard to review a one off hand calc. For that reason, I feel that it's hugely important to be using the same tools as everyone else in your organization, even if those tools might be inferior to your latest, VBA-packed, Excel Tour de Force.

I disagree, for the reasons given by dik. Design inputs should be checked in detail, and the design process should be reviewed, but the design outputs should be checked with an independent analysis, preferably using different software.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[KootK]

I disagree

Are you sure? I have a hard time believing that anyone who's spent time in a high production engineering office would object to calc standardization. I agree that there is a place -- an important place -- for truly independent design verification. That said, I've yet to work at an outfit where there's been time or fee to independently check more than 10% of the work. Frankly, 5% is a stretch. And yet, junior engineers still need timely assignment feedback from their managers etc. I just don't see how that could reasonably be accomplished without a serious nod to standardization.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dik]

KootK... for a similar problem, I often don't do the calcs the same way...

I don't function well in a highly structured environment... I'm happiest when I'm working independently...

Dik

 

[KootK]

KootK... for a similar problem, I often don't do the calcs the same way...

Then I'd argue that one of you should change your "way" to whichever method is deemed to be your firm's version of "correct". Kinda depends on what you're looking at. If you're splitting atoms then, sure, 50 shades of grey and let the creative juices flow. If you're checking punching shear at corner column, there should be something akin to a "standard" that everyone buys into.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

It's OK but not sure it tells me anything I didn't already know.

Thanks. I have some IBC checklist stuff that probably is in a similar vein. While it might not be enlightening for you or I, I wonder if it might be for other, less seasoned pros. I recently started a thread here asking if anybody had canned "how to do structural drafting" guides/checklists. I wonder if this document might fill part of that need. While I do care about how things look, I mostly care that information is complete and coordinated. And my need is for a way to train others that I may work with sporadically to help ensure that I get a product that I'm happy with. I'll see if I can talk my wife into buying this on her corporate account.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[haynewp]

We are trying to get everyone using the same software and standardize calculations but it’s not easy. I check a lot more than I perform original calculations and I use hand calcs, tables and graphs, and spreadsheets I’ve had for years. I also go through as much computer output I can depending on what it is, but I won’t do that for 3D models in programs like RAM and RISA. I get into the models myself in those cases. I think the quick completely separate verifications I do find the most errors, or at least the ones that would be real issues.

 

[IRstuff]

Seems to me that y'all could do with using Mathcad ;-)

I LOATHE looking at calculations in Excel; it takes extraordinary discipline to come up with a readable worksheet that has every units conversion factor clearly identified. And then, are the parentheses all in the right places? Both are easy do's in Mathcad, since units conversions aren't even necessary, and WYSIWYG equations look like the equations you expect to see in a textbook. Numerators and denominators look the way they're supposed to look.

While I won't go so far as to push Mathcad, per se, something similar would seem to be a good thing to standardize on. As with good coding practice, readability is critical to ensuring accurate calculation and ease of checking and validation.

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[haynewp]

We recently bought MathCad but it’s finding the time to develop standardized calc sheets for everyone to use that is difficult. We have used Tedds for years and it is great, but not compared to MathCad for any customizing or creating anything altogether new. Our new engineers don’t seem to learn as well using all these programs versus hand calcs, tables, and graphs that I used more of starting out.