×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Related Articles

Jobs

Communicating structural calculations
13

Communicating structural calculations

Communicating structural calculations

(OP)
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?

RE: Communicating structural calculations

2
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.

RE: Communicating structural calculations

Quote:

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.

RE: Communicating structural calculations

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.

RE: Communicating structural calculations

Quote:

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.

RE: Communicating structural calculations

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

RE: Communicating structural calculations

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.

RE: Communicating structural calculations

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

RE: Communicating structural calculations

Quote (hokkie66)

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.

RE: Communicating structural calculations

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

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Communicating structural calculations

@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.

RE: Communicating structural calculations

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.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Communicating structural calculations

Quote:

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/

RE: Communicating structural calculations

Quote (IDS)

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.

RE: Communicating structural calculations

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

RE: Communicating structural calculations

Quote (dik)

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.

RE: Communicating structural calculations

Quote (JAE)

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.

RE: Communicating structural calculations

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.

RE: Communicating structural calculations

Seems to me that y'all could do with using Mathcad winky smile

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.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Communicating structural calculations

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.

RE: Communicating structural calculations

(OP)
Thank you all for the great responses. This is truly helpful.

Hokie66 - I will try to implement that. Your advice is similiar to that given for general mathematics, which ill reconsider. My previous objection were that the plain amount of calculations + meta-text makes the whole document balloon. I guess its an experience call, knowing what is essential to communicate.

WARose - Thank you for the tip. I bought it at the spot, looks like a sound investment.

Motorcity - Do you treat the references as footnotes, or is there any specific way of referencing? We work mainly from the Eurocodes, so theres not that many obscure equations. I can imagine thorough referencing also help in standardizing the calculations between people, so that the use and context is easier to read up on later.

Drawoh - Word seems ubiquitous in this context, although Ive never understood its uses over Latex. Would you consider equations written in plain-text to be readable, or is the equation engine of word/latex critical? Ive been experimenting at home with a Markdown workflow recently, primarily using the fantastic software Calca and .css to standardize the pdf output. Its similiar to Mathcad, but with plain text at the cost of a cup of coffee. Problem is, it just doesnt look as pretty as a true equation engine does, although using Latex for the math and markdown for the rest is a possibility.

Kootk - Do I get your #2 point correctly as that the software which allows easier combinations of calculations with images support actual understanding, and therefore help prevent the large mistakes? That sounds reasonable, considering how useful it is to diagram next to hand calculations.

IRstuff - Yeah, its a world of difference between the readability of excel and mathcad. Ill try to emphasize that aspect a bit more.

RE: Communicating structural calculations

I like calculation sheets, or computer output, which have separate ruled columns, usually on the right, for references and explanatory notes.

RE: Communicating structural calculations

spaderess - we only formalize calcs if they are submitted to the municipality or client for review. It varies by engineer how references are made. Most people simply provide a list of codes and references since anyone checking calcs should be familiar with your equations and where to find them. However, there are some people who reference each section of the code for each equation they use. I see that as being tedious and unnecessary. With regard to everyone using the same software or method for calcs, that will never happen in a large office. We have several software packages that essentially do the same thing. Some are more user friendly and robust than others, but engineers are free to use any software or hand calcs they choose. I don't think its reasonable to expect everyone to be proficient at using the same software. Engineers come from various backgrounds and have different technical abilities (or lack of). As long as you produce a sound structure at the end of the day using reasonable techniques and resources, you good to go.

RE: Communicating structural calculations

spaderess,

Microsoft Word has a perfectly functional equation editor. Click on the Insert tab.

I use Linux at home. I have learned LaTeX and I like a lot of stuff about it, including its equation display. This is what TeX/LaTeX was originally written to do. I can send the LaTeX files out in PDF format. The equations do not display well in HTML, and I don't think they display at all in RTF. I have not tried to do the actual calculations in Octave, to be integrated with LaTeX. This would be nifty and it should be possible. Octave calculations can be processed into graphs using GNUplot, and integrated with the LaTeX file. LaTeX can be run from a GNU Makefile, which is convenient.

Microsoft Word does an adequate job of formatting and displaying equations. I can send the results out as a readable and writable file, to be reviewed by engineers. I have done a number of safety calculations recently, and the results either were vetted (thread507-409684: Wind Loads), or they ought to have been vetted.

--
JHG

RE: Communicating structural calculations

There are indeed a number of programs that can create equation graphics, but aside from Mathcad, TKsolver and a couple of others, none can use those beautiful graphics in an actual calculation. Therein lies the dilemma; documentation by those graphical approaches leaves open the possibility that the documented equations are possibly incorrect, or that the actual calculations are different from the graphics. And if the actual calculation is "tweaked" for whatever reason, you now have to go back and correct the graphics.

While Microsoft Word Equation Editor is essentially a free add-on, Mathcad is, unfortunately, VERY expensive. TKsolver is more affordable: https://www.uts.com/ItemDetails.asp?ItemID=0100-50... There's an even cheaper option, which is Mathlook for Excel: https://www.uts.com/ItemDetails.asp?ItemID=1100-40... I've never used it, since I have Mathcad, but it might at least get you a pseudo-self-documenting worksheet.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Communicating structural calculations

Quote (MC)

I don't think its reasonable to expect everyone to be proficient at using the same software. Engineers come from various backgrounds and have different technical abilities (or lack of). As long as you produce a sound structure at the end of the day using reasonable techniques and resources, you good to go.

I agree. I wasn't suggesting that everybody be proficient at the same software. And I recognize that 100% standardization is wishful thinking. What I'm talking about isn't ETABS/RAM stuff, it's the dozen or so company vetted spreadsheets that most offices maintain for doing common things. You know: spread footings, openings in steel beams, column load take-down, yada yada. It is my strongly held opinion that, where such internally vetted tools are available, they should be used with very few exceptions. In my experience, at least 80% percent of EIT, one off spreadsheet will contain an error. Seriously.

Quote (OP)

Kootk - Do I get your #2 point correctly as that the software which allows easier combinations of calculations with images support actual understanding, and therefore help prevent the large mistakes? That sounds reasonable, considering how useful it is to diagram next to hand calculations.

That's precisely what I was getting at. Doing a meaningful review on a endless, streaming effluent of numbers is painful and time consuming at best. The accompanying sketches are the most valuable part I feel. How did you decide you're trib area? Unfortunately, because hand sketches take time and force folks to go non-digital, they seem to get used too sparingly. Clipping and pasting sketches into some kind of digital scratch bad seems to produce excellent results. As an example, a rockstar EIT that I used to work with would give me calcs like this:

- Load casing done in matrix form so that you could easily see what when into determining max/min without having to wade through the results of every combo.
- Pasted snippets of the code provisions where it wasn't completely obvious what code provisions had been drawn upon. Folks mostly have access to digital codes now so it's easy.
- Snippets of the framing plans with hatching showing the trib areas for beams. Same for columns with snips of the architectural sections to show unbraced column heights.
- Snippets of SAP2000 results. Moment diagrams, deflections etc.

It's nice, as you can imagine. In this day and age, it's all to often the case that "checking" means getting directed to some folder full of models and half baked "spreadsheets". Easier just to redo the design myself. And I'll do that for some spot checking at the end. Mid-project though, I need to be able to see that things are being done correctly in order to keep the project on track.

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.

RE: Communicating structural calculations

Haynewp: That's pretty much the same that I do...

Dik

RE: Communicating structural calculations

Quote:

(spaderess)

WARose - Thank you for the tip. I bought it at the spot, looks like a sound investment.

The version I've got is from 1991. I think there is a later one. But I love this one because all the solutions are hand calcs. It's like looking at a good set of calcs from a older engineer.

RE: Communicating structural calculations

For normal stuff the reviewers accept spreadsheets and/or mathcad files, not really very tidy and clean.

For fancy stuff I use LaTeX. For a faster typing I use mathcad and then use a mathcad to LaTeX parser I found on the internet a while ago. This helps make calculations faster. And the document is pretty.

When I work with people unfamiliar with LaTeX, then Word is the way to go, but it is a pain in the ****. When I learned LaTeX I forgot everything about Word.

About the completeness of the calculations, when doing obscure works (e.g., complex shells) where I work it's standard to make the calculations a little bit less legible such that only the reviewers (people who know the calculations) are able to understand it, so people unfamiliar with the subject feel a bit lost. This typically involves removing steps and using obscure symbols. For handwritten calculations just copy your doctor's handwriting.



RE: Communicating structural calculations

2
MonsieurR,
If your complex shell collapses, your undecipherable calculations won't help you.

RE: Communicating structural calculations

I disagree, they are not undecipherable, just harder to understand. BTW I didn't come up with the idea!

RE: Communicating structural calculations

My first job, the supervising engineers were flexible on format, but my calculations were gone through with a fine tooth comb. I started using mathcad - after some practice, it was just as fast (and later on faster) as doing numbers by hand. Huge bonus is that human calculation errors were eliminated. Going between metric and imperial, a huge time waster, was automated (Canadian here).

In the process I ended up reusing huge chunks of spreadsheets for similar projects. By the end of my tenure there I had automated 75% of my day. I could show up and work 2 hours a day, spend another 2 developing increasingly complex mathcad sheets, and read/study/relax the other 4. The supervising engineers were hesitant to give me any more work because I was already pumping out so much.

Refusing to use mathcad because it takes too much time is akin to refusing an offer of 100$, to be given next month, to receive $10 today. You will save time, and the benefits will be realized very soon.

RE: Communicating structural calculations

Monsieur,
Whatever...it is a poor idea to intentionally obfuscate.

RE: Communicating structural calculations

I personally try to tell a story. First I state the background info. Then I move into the design standards, assumptions and specified data. Then I go through my calcs following the load path for tge most part. For example, for gravity loads I would start from the roof and work my way down to the foundation. For lateral loads I’ll start with my diaphragm loads and go down from there.

RE: Communicating structural calculations

Quote (NorthCivil)

I started using mathcad - after some practice, it was just as fast (and later on faster) as doing numbers by hand.

I am trying to get to this point with Mathcad and have made a few sheets for repetitive stuff that I do. The biggest aggravation for me is that I do a lot of one-off custom calculations that rely on hand sketches and free body diagrams to explain. I'd like a quick and easy way to import a hand sketch to the Mathcad sheet alongside the calculation. It seems by the time I sketch it, scan it, import it, format it after it throws off the sheet layout that it's quicker to just do the calculations by hand.

RE: Communicating structural calculations

I'm another MathCAD convert. I like the easy integration between math and text which can make it an easier task on the reviewer by explaining what you're analysing, why and the method you're using. It's easy to paste screenshots from AutoCAD too if it starts getting a bit "wordy". Having the math presented very similar to hand calcs makes the sums easy to follow too as all steps to the solutions are visible. Don't get me wrong, this wasn't an overnight process to jump into but well worth it in the end.

RE: Communicating structural calculations

@bootlegend -- one option is to get a digitizer, ala touchscreen or pad, a stylus, and Windows Ink or equivalent. There are many approaches to freehand drawing directly on a computer these days.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Communicating structural calculations

All those that like or are considering Mathcad should take a look at SMath Studio. I like Mathcad and all but at $1000 a seat I feel it is way to expensive considering you are basically buying a program language. They are also awful about breaking old sheets with new versions.

Those of you using LaTex and/or Word may want to look at using python along with Jupyter notebooks or SageMath.

RE: Communicating structural calculations

2

Quote (dik)

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

I hear 'ya on that. I've always thought it a bit cruel how things work out for our ilk. Being good at doing production requires a degree of attention to detail bordering on autism. Being good at managing the production requires one to be a "more than one way to skin a cat", 80/20 kind of guy/gal. It's rare that both skill sets come naturally to the same engineer.

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.

RE: Communicating structural calculations

Okay, I'm response #39 & you guys (as usual) are mostly way above my head. I'm going to have to check out Mathcad, because I generally do hand calcs and my notes include code or design book references noted in the margins because even though I usually know where they are it saves time later, especially if I have to rewrite them for someone else. And that is always my big issue, occurring much more frequently these days: when asked to submit calcs, I have to rewrite them to make them presentable. I really can't conceive of getting out of that without using more design programmes (I do have some, I'm just not that comfortable with their invisible parts) but on the other hand I find that anyone asking for calcs is automatically relieved and immediately accepts something if it's computer generated. It seems to me that it's usually a corporate (read bureaucratic) response to something they don't understand to ask for calculations, & to be immediately reassured if it looks like the responder uses a computer.

RE: Communicating structural calculations

I used to be the biggest MathCAD proponent around. Less so now.

- Crap backwards compatibility.
- Bought out by big parent company.
- Expensive. They just ditched perpetual licensing and subscription is $600 US per year.
- Somehow, Prime 4.0 still doesn't have as many feature as V15 had back in 1859.

SMath Studio is looking better all the time. I know it has some limited programming features which is great. Does it have things like goal seek and hidden regions? Talkin' to you rn14.

I'm more than a little bitter about MathCAD really. Around 2000, I placed my bet on MathCAD being the future and let my Excel skills slide. I regret that choice intensely now. Trust. That is what is now absent from my relationship with MathCAD.

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.

RE: Communicating structural calculations

KootK... I use SMath Studio and find it pretty useful. Not as many bells and whistles as MathCAD, but totally functional.

My new TI calculator is proving to be very useful... it does a form of 'pretty print' and I can print the files to a *.pdf file for saving. Can add comments or can just do 'meatball' calculations... it saves them all. It has a spreadsheet that easily rivals excel and for more complex operations.

MathCAD went downhill and the price soared when it was taken over by the 'bigname' company.

Dik

RE: Communicating structural calculations

Neat, pretty much like my TI calculator... does Excel take the data from the formulae? or do you have to key it in separately?

Dik

RE: Communicating structural calculations

I have been using the Smath studio also. Once you get the hang of the input style, it works well. (i just wish you could change the native units to pound, feet, inch instead of always defaulting to SI units)

I usually scan diagrams/sketches into a PDF format or Jpeg. Then I use windows free screen snipping tool to cut and paste into Smath.

The best thing about Smath studio is that it is free!

RE: Communicating structural calculations

I’m a bit contra-wise to many in that I loath MathCad output but like Excel output. But, that said, the point of the Excel output is high-production, say, for example, designing wooden beams or joists. It must be verified as accurate with the results back-calculatable but not necessarily pretty. MathCad, on the other hand, looks to me like mathematical derivations of formulas and it hurts my eyes. Of course, for me nothing is better than hand calculations. Just my opinion.

RE: Communicating structural calculations

" MathCad, on the other hand, looks to me like mathematical derivations of formulas and it hurts my eyes. Of course, for me nothing is better than hand calculations. "

These seem contradictory; Mathcad, at its basic level, essentially does "hand" calculations and documents them as you go along. There may be something to be said about doing them on a calculator, but Mathcad allows you to avoid making mistakes in unit conversions, etc.

How do you document your hand calculations? Do you write them on a sheet of paper?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Communicating structural calculations

It doesn't seem contradictory to me; to me hand-written calculations don't have the visual rigor and formality of the MathCad calculations that I've seen. I'm referring to multiple numerators and denominators with super and sub-scripts, exponents, all the units documented in each equation...all very cumbersome to my eyes.

Like I wrote, I know I'm in the minority on this one. But I also prefer wooden pencils to the mechanical ones, wood furniture to particleboard furniture, unlined leather boots to goretex ones, brick vs. vinyl siding, homemade pies to store-bought ones, manual transmissions, rear wheel drive, etc., etc...

RE: Communicating structural calculations

right on Archie246.....add copper to pex waterlines to your list

RE: Communicating structural calculations

OK... it just seems to me that documenting with pencil/paper would result in duplicate work and potential for transcription errors.

I try to do as much as possible where I avoid hand entering numbers more than once. Everything after the initial data entry is copy/paste only.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Communicating structural calculations

Hokie66 said, “Don't just include a bunch of numbers in your calculations…”. Heck I don’t even see a bunch of numbers in some of the submittals that we get. The last calculation package I reviewed just listed a bunch of equations with symbols that were not clearly defined, with a magical “answer” at the end. The only way I could verify any of the numbers was to do my own calculations. In the “old days” (ten years ago), we would usually get calculation submittals that were easier to follow.

On the other hand, we also sometimes get reams of paper with nothing but numbers. (Equally useless.) Manual calculations are becoming a rarity. This is not good.

I don’t want to “process” calculation submittals. I want to review them to be sure that the person who did the calculations has a clue.

RE: Communicating structural calculations

MonsieurR,

You sometimes take a little extra time to intentionally make your calculations confusing and difficult to understand? Respectfully, that is not a good thing to do.

Unfortunately these days, it seems many engineers don’t intentionally strive to make their calculations undecipherable. They are just naturally a confusing mess.

RE: Communicating structural calculations

2
Cliff234:
If you were bashful about say it, I’ll add a couple sentences to the end of your last post. The calcs. are a mess becuase the people doing them (engineers?, come on) don’t have the vaguest idea what the hell they are really doing. They have no engineering experience or judgement to guide them, they have no intuitive understanding of how the structure works, they don’t seem to have a boss that gives a damn or gives any meaningful guidance, just get er done and out the door. We have E&O insur. to cover the rest, or any problems you produce. They can’t do the problem or analysis long hand, they just don’t know how. They couldn’t do it without the software they were given to use, and they really don’t understand how to use that software, or model the structure, or how to interpret its output either. So, you get a ream of paper with numbers on it, and it is the old saw..., ‘dazzle them with data, baffle them with b.s., and maybe they will go away.’

RE: Communicating structural calculations

Quote (MotorCity)

right on Archie246.....add copper to pex waterlines to your list

Off topic but this made me laugh.. I just had my house re-plumbed; the estimator came and gave me a quote on the spot, in writing. I looked it over for 10 seconds and asked him to re-estimate using copper line and fittings instead of PEX.

He looked at me as if I'd just told him I was born on Venus and wanted my home's plumbing to be constructed from chocolate and vanilla frosting.

Back on topic..

As usual for any post I write in the SE forum, I deal with a reasonably different scenario; much of the calculations I deal with are either FEA results or quick calculations of a small aspect of a system.

My approach is always the same- I don't ever read a ream of calculations line by line looking for errors; I just take the same inputs, units and assumptions (or model and conditions if we're talking simulation) and see if I get the same result.

Granted, repeating the work is maybe not feasible for something like evaluating the engineering of a whole building, and there are other drawbacks with this approach; but I've found that if I take a couple of pages of calculation and start stepping through line-by-line, it can often become difficult to avoid getting locked in to the other person's assumptions when they may not be correct.

This, of course, requires that me and the person I'm backing up or evaluating have access to all of the same tools and documentation, which again may not be possible if you're evaluating things after the fact.

RE: Communicating structural calculations

As others have said, don't just splat a load of numbers on a page. Lay it out sensibly, describe what you are doing (words and sketches) and use a program which illustrates the calculations when printed (e.g. not excel in it's basic format).

For 'simple' calcs I will usually just overmark the design drawing and add any checks at the side.

For 'moderate' and 'difficult' calcs I will do something like below using MathCAD.

Intro: Describe the project, what I am checking, any obvious constraints, problems. Why I'm going it the way I am doing it.

Methodology: Only for complicated / long calcs, I'll include a step by step break down of what I'm about to do so the checker is forewarned.

Assumptions: Any assumptions go here.

Loading: Details of the applied loads, load cases, factors etc.

Structural System: Describe how the loads are transferred / resisted. Sketches!

Calc Part 1: Brief text description of what I'm checking, sketch if required (I try and work from the applied load to the foundation, checking what's relevant as I follow the load path). Calcs, with descriptions next to each parameter / equation to aid understanding.

If I do any computer modelling etc. then I will include screenshots from the model, showing e.g. geometry, section sizes, applied loads, bending moment / shear etc. as relevant, utilisation plot.

I do usually rely on the checker poking at the model a little bit as well as reading the calc report.

etc.

Conclusion: State what has been checked, what is OK, max. utilisations, etc. Any restrictions on use (e.g. max. load of 5kN/m2 only) etc.

Appendices: Drawings, reference data, print out of relevant pages of standards, etc.

RE: Communicating structural calculations

dhengr, You hit the nail on the head. Many "engineers" don't have a clue as to how to confirm via manual calculations whether their computer analysis is correct. I believe that if an engineer can't validate their computer analysis with basic manual calculations, then they should not be using that structural analysis software. Would we let a young pilot fly an airliner if they no actual experience flying planes, but they did have a lot of experience "flying" with their computer flight simulator software at home?

RE: Communicating structural calculations

Quote (KootK)

Unfortunately, because hand sketches take time and force folks to go non-digital, they seem to get used too sparingly. Clipping and pasting sketches into some kind of digital scratch bad seems to produce excellent results. As an example, a rockstar EIT that I used to work with would give me calcs like this:

- Load casing done in matrix form so that you could easily see what when into determining max/min without having to wade through the results of every combo.
- Pasted snippets of the code provisions where it wasn't completely obvious what code provisions had been drawn upon. Folks mostly have access to digital codes now so it's easy.
- Snippets of the framing plans with hatching showing the trib areas for beams. Same for columns with snips of the architectural sections to show unbraced column heights.
- Snippets of SAP2000 results. Moment diagrams, deflections etc.

KootK, can you describe this in a bit more detail? What were they clipping sketches/code provisions into - MS Word file, MathCAD? Could you post a sample by chance?

What I like is doing all the wordy parts of a particular design (say, designing a steel beam-column) with a sketch by hand on design paper, then use my typical beam-column Excel spreadsheet to do that actual computations/code checks. THEN, write on the excel print out any notes or relevant info, and finally staple the pages together.

RE: Communicating structural calculations

Regarding point 1: A while back my supervisor shared with me a document titled 'Model procedure for the presentation of calculations' by the Concrete society (technical report '5' I believe). It's a fairly old document but it did present a rather systematic way of documenting calculations. It may be the thing you're looking for.

RE: Communicating structural calculations

Quote (IRS)

How do you document your hand calculations? Do you write them on a sheet of paper?

I use a pdf printer driver with my computer and create *.pdf files of my spreadsheets, etc. and copy these to the project file. If needed, they can be printed out.

Dik

RE: Communicating structural calculations

I always find it handy if the drawings match the calculations, just saying because I seem to find more often than not that nothing matches due to design progression/laziness. Engineer designs something without a thought to how it's build /detailing, gets drawn and issues highlighted, design modified by draftsperson (and perhaps engineer), calculations (and sometimes analysis) never updated. I've wasted the fee for peer reviews before I even start trying to figure out what's going on regarding the info I've got/not got, drawing/calculations discrepancies, etc.

One other point I'd make is any external peer review shouldn't substitute for robust internal verification.

RE: Communicating structural calculations

I rarely if ever have to provide calculations in my business other then when I provide metal stud shop drawings.
I typically fully draw the detail as it will be shown on the structural sheets using seat-of-the-pants engineering and some quick calculations.
That way I have already worked out the constructibility issues.
I then print it out on 8 1/2x11 and add the actual confirming calculations on top. It is easy to draw arrows to each connection or member and show the calc for it.

RE: Communicating structural calculations

A Webinar based on the document JAE linked to earlier in the thread (A Guideline Addressing Coordination and Completeness of Structural Construction Documents)
Link
Have not viewed it yet so cannot attest to its usefulness,but thought others might be interested.

RE: Communicating structural calculations

A good calculation sheet needs to read like a good story.

The only purpose of calculations is to help an engineer make a decision. And humans, generally, can only make a decision after they've framed the problem in context of a story.

Therefore, your calculation better be written as if it was a story to help you, your future you, or someone else make or understand the decision at hand.

"We shape our buildings, thereafter they shape us." -WSC

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close