Why Document Calculations?

[sdz]

Why do we have to document all our calculations?

We seem to waste a lot of time form filling, documenting, filing, to produce a mountain of paper that mostly never gets looked at again.

 

[rholder98]

For the one time it does get looked at again.

It really helps when doing a peer review, or checking someone else's project. It even helps when checking your own work. I have often found myself wondering what I was thinking when I designed a certain thing, and having my calcs answered the question.

 

[rholder98]

I had the opportunity recently to review calculations produced in the late 60s by someone in my company. It was a four-story concrete building. Two-way slabs, and moment frames done by hand, with moment distribution. It was really amazing. Very neat and well organized, and everything was written out, describing the steps. Textbook. None of my calcs ever look that good.

 

[UcfSE]

Neatness counts.

 

[GregLocock]

sdz

Because one day you will have to go to court and justify your design.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[MichSt]

I work for a consulting firm doing bridge design for state DOT’s, and typically part of our deliverables to the DOT will be the engineering calculations. So, there is an obvious reason to document the design calculations. This must not be the case in other areas of structural engineering.

Also, documenting and backchecking design calculations is part of having a proper QA/QC process, as mentioned by rholder98.

Documented calculations are also helpful to have for future work that’s similar to what you have done in the past. For similar designs, old calcs can be used as a starting point for your new designs. You can kind of build up an archive of design samples with your old calcs.

 

[Ron]

sdz...Greg's right. That's one of the most significant reasons we document things in engineering.

My practice includes a substantial amount of Forensic work. I have seen cases where good documentation caused the litigation cannon to get pointed elsewhere. I just recently was involved in a case where poor documentation cost a company about $500,000 US (in cold cash) not to mention the loss of continuing on a multi-million dollar revenue project.

Document everything (wish I could always follow my own advice!). Throw away draft reports. Keep only the final version of anything your produce. Be able to reproduce the project many years from now...sometimes you have to do that.

 

[Jordonlaw]

sdz,

In the aerospace industry where the customer often wants to change the use of the product or add more stuff it is often necessary to go back to the original calculations and see what the consequence of these changes would be for, say, fatigue stresses. It is also often a requirement; the customer demands calculations are kept for at least the lifetime of the product in case of in-service issues.

 

[Loui1]

#1 Liability

#2 Liability

#3 Proof that you did things right.

#4 If a modification is done to a structure at a later date it makes it much easier to see the calcs.

Youve never been sued egh?

 

[sdz]

Thank you, everyone, for your comments.

 

[henri2]

Also enforcing jurisdictions often require them to conduct an effective and meaningful plan check.

http://www.eng-tips.com/viewthread.cfm?qid=141744

 

[rb1957]

a cynic might say "'cause we get paid more if we spend more time working on something",

clearly, there are any cynics around !!

 

[cjd97]

I too have seen the awesome textbook calcs from an "old timer" engineer. It's wonderful that they had the time and/or were quick enough to do that. Would anyone now have time to produce those kind of calculations? I guess the problem is now we are getting less money for the same jobs, or engineers are not as bright as they once were. Seeing as I'm an engineer, I hope it's not the latter