What calculation is being made for estimated reinforcement volume?

[francisco.condeWE7HG]

Been trying to find which formula is revit using for the builtin parameter "Estimated Reinforcement Volume" but with no success.

Thanks

[gevanKGYB4 · Accepted solution]

From what I understand the "Estimated Reinforcement Volume" shown is the total volume of reinforcement bars being hosted on that particular structural element. It is being called "Estimated" due to the fact that some rebars may overlap in between elements so Revit maybe saying something like "This is the rebar volume being hosted here but there are overlaps, so you know maybe this is only good as an estimation. You may have to calculate and check the rebar volume yourself if you want to budget this."

[francisco.condeWE7HG]

Thank you for the reply.

I misjudged the scenario that I had in my project. I was getting different values in "Estimated Reinforcement Volume" for 2 reinforced isolated foundations with exactly the same rebar volume (so, no overlaps cause I had no reinforced column or beam attached to it).  That's why I thought it was a calculated value.

Meanwhile I contacted Autodesk Support and this error was already been recently noticed.

https://knowledge.autodesk.com/support/revit/troubleshooting/caas/sfdcarticles/sfdcarticles/Estimate...

Either way, I have recently finished a dynamo script to calculate it by myself as you suggested avoiding this type of situation. We never know if this is going to be solved tomorrow or in 2030 🙂

[RDAOU]

Is your issue with what/how is being calculated or the term estimated or the changing value when rehosted?

[francisco.condeWE7HG]

Hi @RDAOU 

My issue is that there is no documentation on this parameter saying what it is and how is being calculated. (At least I couldn't find it anywhere)

The rest of the conversation was a consequence of trying to understand how it works where I found 2 different bugs. 1st - The reassigning scenario that the Case is addressing;

2nd - The parameter in same cases only partially identified the rebars of an element, leading to miscalculation on the volume.

[frconde]

Hello again, 4 years later. This issue is not resolved, as I mencioned I've been able to correct this by using dynamo. Please watch the following scenario:

- 2 Isolated Foundations ( 2.00x2.00x0.70m - 30mm cover) with the same size and rebar. The rebar was modelled in 3D, picking faces to define the shape and path, #10@200 on the 4 directions.

- Estimated Reinforcement Volume, is different on both.

- Yes, the difference is not significant. But why? I waste my life figering out ways to override this type of errors because I can't trust autodesk.  it's 0.7% of difference, with absolutely no reason to be. In a smaller project, fine. On a massive one.....? Can't people be accurate? this is engineering, not religion. Today is 0.7%, tomorrow might be 7 ou 70% on another type of element. The reinforcement volume parameter, should be the actual volume that is hosted on the element, nothing else. If this was the case, it would be possible for all structural engineers to achieve instant rebar densities per element with a simple parameter formula. But no, we can't trust autodesk again.

- If I create a rebar schedule and base the calculation on the rebar volume, the result is absolutely correct. 

Best part is, if you create a brand new isolated foundation and reassign the rebar host to that foundation, the estimated reinforcement volume is corrected and equals the correct one.

I have 4 to 5 different scripts, have to update them every revit release because autodesk can't be trusted. I will ask for a random % on a discount for the licenses, seems legit and has the same principle applied on this type of errors.

Thanks in advance and I already apologise for the frustation.

[jay_colcombe]

Out of interest I repeated you example in Revit 2026 and here are my findings Placing in a Plan View or 3D I had no issues with conflicting values(but this is a small sample)

However I do get differing Values between Standard Placement and Free-form Placement and even converting the Free-Form to Bent shapes has no influence.

I did not however is if you change the Free-form > Bar Alignment this affects the Estimated Rebar Value

And if you review the Bar length from the Plan Placement to the Free-form there is also a significant difference

[frconde]

Thanks for your interest on the matter.

I wish we could at least assume that only with Free Form placement that we get problems but how can we trust? On a large scale project, checking this for each element would take hours and hours.

Imagine this, instead of getting a direct parameter that should sum all the reinforcement volume hosted in an element, I need to go to Dynamo, grab all elements that have rebar hosted, get all the rebar and group it by parent element, calculate the total weight of rebar per element, push the value to a shared parameter so I can get the actual rebar weight correct with 100% accurecy. Mind blowing... And this is for dynamo users, for non dynamo users, good luck