REVIT Math - PROVE IT!!

[vaughndave]

I have been asked to research what some of the industry is doing as far as “proving the math” in BIM packages. REVIT would not be excluded from scrutiny in this case. Point being, how are others showing that the calculations that are processed, are calculated correctly and what methods are being used? How do we show proof of that using BIM? Obviously it would be nice if we just submitted schedules and that would be adequate, however, Design Analysis is submitted at different times of the project duration and calculations are always included. The verbage in the help and text documents in REVIT is not a viable option. Any ideas on this subject matter?
Best regards,
Dave

[twiceroadsfool]

I know plenty of people who- at one point or another- did things in revit/ArchiCAD/Digital project, and then did the math by hand for comparisons sake. i doubt anyone has bothered to publish an actual set of comparisons, but all of the inconsistancies are well documented. (Paint tool, wall heights, etc)

[m20roxxers]

I doubt it matters at the end, you are liable for the information you send on anyway.

So if it doesn't ad up you fix it. I'm only aware of one guy who got in alot of trouble for scheduling windows, and it turns out he was scheduling the wrong parameters he was scheduling type parameters for sizes and someone had create instance options and left the type ones filled in.

We don't have to prove BIM, if we stuff up we get pay for it the hard way.

[jeffh]

The verbage in the help and text documents in REVIT is not a viable option.

I am curious about this statement. What verbage are we talking about exactly? Is there anything that could be done to make this verbage work for your purposes, or is it categorically out of the question becasue it is from the help files of the application, so what it says is discounted?

Just checking to see if there is something that could be changed in the help files.

[vaughndave]

Hmm...Now I really have to wonder if I have posted in the right arena here?
I am surprised at the responses to this so far, maybe I just need to elaborate.
I am not an Engineer nor an Architect. That being said I am quite knowledgeable of all disciplines being employed for over 25 years in the industry. I learn something new everyday and I certainly learned a few things when asked to research this subject matter.

If you are an Engineer or Architect..etc and you are sealing or approving documents that are to be used by a client for any purpose, being responsible and legally bound, all parties involved should feel confident that the methods used to generate the information is industry accepted practice.
There seem to be 3 or 4 factors that decide how the deliverable is accurate and professionally designed.
- The client takes the opinion that they have hired a professional and takes them on their merit and experience that the end product is designed correctly.
- The designer (may or may not be an actual licensed Engineer or Architect) of the project must have it checked by another responsible party before the Engineer will submit the work. All the firms I have worked for, have established quality procedures that must be followed. Computation checking is a part of this process.
- The client REQUIRES the design firm to submit all the calculations and design research at certain intervals of the projects timeline. Corps of Engineers is a good example of this as they required a Design Analysis to be submitted at certain times during the project.

At our firm we don't take any software for granted. Some packages area actually certified for use such as Mathcad, STADD, etc. these do not require proof of accuracy once certified and they are re-certified at each major version change.
CADD programs such as Autocad and Microstation do not get certified, since the information contained in those files is mostly generated from sketches, external conversations and paper computations. A print is made (paper or electronic form) and that is checked for accuracy and completness.
BIM packages are a completly different ball game. I don't exclude any of the major software vendors here. These are sophiticated software packages that certainly have earned their merit. However, we are taking them for granted, thinking that the software vendor knows everything about what needs to happen for a complete design to be correct and accurate. What happens if the table that internally controls the sizing for duct or piping has a typo? If it's a subtle mistake and not obvious, it would go out the door unnoticed. Yes, it probably will get built and still work in this case, but you get my point.
So, for those of us that do need the "Math proof" ,we still do it the old fasioned way
spread sheets and long hand calcs on paper.
I am just wondering if there is any way for the software vendors to help us out by providing a way to push out the calcs that are done for ductwork, piping etc to a spreadsheet or the like?
Sure is easy to just fill in fields for element properties and start designing on the fly. Those fields were derived from somewhere, be it the software natively, or customized by the person inputting the information.
Volume is calculated: Length x Width x Height. Or is it???? <<Who said that?

[m20roxxers]

I think your missing my point.

We certainly have check what we use Revit for to make it's right.
So when we hand over tonnages, rates, area's from Revit we spent the time previous to make sure workprocesses and methods are correct.

As for the Duct, wiring, pipe sizing tools. Autodesk have published the PDF's of the systems so you can see how this is analysed.

[vaughndave]

I am not trying to get an argument goin here.
I want to find out if other firms systems of "Checks and Balances" have changed since adopting BIM and how. I am not missing your point m20roxxers. You haven't really explained anything about how your workflow is since adopting BIM. That's really all I am interested in.

"So when we hand over tonnages, rates, area's from Revit we spent the time previous to make sure workprocesses and methods are correct."
Who's doing the work and who is checking it? Someone that knows REVIT gets markup and then "traces it" into the model?
REVIT is doing the calculations, why can't we see it instead of just examples of how it does it? What about all the inputs that goes into these models ie. custom instance property fields that are prone to human error. All the stuff we need for design is not delivered therfore we create it or get it from an outside Vendor and we all know that isn't everything it's cracked up to be. We have to be able to check the inputs used to build the model easily.
------------------------------------------------------------------
JEFF H.:
I attached an example from REVIT MEP.

[m20roxxers]

Ahh workflow, sorry didn't mean to sound grouchy just wasn't sure the point you were trying to hit.

We use the Revit standards checker, Navisworks and Excell to run checks on our data. mostly it's to check the data exists and it's not massive or small number. We have a couple more checks that will check span sizes and so forth aswell.

As well as good old fashion human checking.
We also have internal views setup with view templates to highlight particular model elements in order to make sure we haven't missed anything and it's all been assigned.

In terms of proof we don't have to prove it anyone but ourselves. Our engineers check our numbers that Revit spits out, also we have checked our data in the past by providng it to contractors and against steel/reo detailer estimations with accurate results, our services guys are getting much better results these days with items/parts and sizes as our team and standard mature.
We ran checks to determine impacts, on openings vs voids, checking making sure counts are right, parts are correct etc. sure volume descrepencies are taken care of, now we have a set of best practices, which changes every year