US engineering requirements for reinforcement - opinions ?

[pawelpiechnik]

In US, reinforced concrete  schedules are traditionally created by engineers by adding the reinforcement information as text into the documentation directly, or by adding property data into the Revit model families which is read into the schedules.  However, there is a growing number of engineers interested in generating 3D rebar in Revit which then creates the scheduled reinforcement.  This is not for rebar detailing per se but just for automating the design process. The 3D rebar can later be detailed into rebar fabrication deliverables by the subcontractors, or by the engineers if they provide that service. The extra benefit here is that the trades in the field can use the 3D rebar to better visualize and plan the installation on site. This can greatly reduce waste in both fabrication and in the field.

Do US based structural engineers see value in modeling 3D rebar if it is generated from the structural design and then scheduled? 

Looking for your opinions…

Thank you

Pawel

[Anonymous · Accepted solution]

Hi Pawel,

I think this is an interesting question around opinions on driving full 3d rebar in models for better coordination and downstream fab use. 

I'd like to pose a similar/further question to try and gauge interest levels:

If you are a US based engineer and typically prepare concrete designs by using a three span continuous beam/slab diagram with prescribed bar groups and lengths relative to the the span,

then schedule actual numbers of bars in each bar group for a particular concrete beams similar to this:

Is this a process you are doing manually now, and would you be interested in a Revit based solution that automated this design and scheduling for you (in a controllable way) based on ACI required rebar calculations and automated scheduling per a customizable three-span layout?

To Pawel's question, this automation could be extended to push real bars into your model for full fabrication based on a standardized layout if you wanted to take this to the next step of full 3D rebar modeling. 

I'd be very interested to see if there is interest in automating US based scheduling. 

 -Ken

[bosborne]

I think an important question here is "At what point does the engineer "optimize" the rebar?"

Analysis may often find that 10 different beams need 10 slightly different reinforcements, but if "by inspection" each of those beams is essentially the same, the engineer might prefer to just clean things up and provide the same reinforcing in each beam and schedule them all as the same.  Reinforcing optimization is not always the lowest weight, but sometimes the easiest to follow in the field. (100 unique beams vs 10 unique beams repeated 10-times each).

If the workflow you guys are suggesting is Analysis/Design Info (Area Steel requirements)-Revit-Generate Rebar-Create Beam Schedule, then I think that will be a hard sell, because then the engineers would have to go in and "Clean Up" the resulting reinforcement mess in Revit in order to get a clean schedule that has some logic to it.

But if the workflow could be Analysis/Design Info-Revit-Create Schedule-Generate "design" Rebar from schedule.... that could have some benefit.  The "design" rebar could then be further developed by a rebar detailer to look at max bar lengths, lap splices, piece marks, etc.  But the design rebar might be suitable for pricing takeoffs, some clash detection, section and detail generation. etc. 

So...Does the schedule create the rebar or does the rebar create the schedule? Which is the "Tail" and which is the "Dog"?  

From reading Ken's answer, it looks like he is a proponent of the Schedule First, then Generate the Rebar. 

[Anonymous]

Thanks for your response.  I feel like you've hit on the crux of the issue.  I'm definitely proposing that, from the engineering side, the calculated required reinforcing based on analysis drives generation of the *schedule*.

The idea is that the schedule generation could be done on a "beamline" by "beamline" or on groups of beamlines initially identified by the engineer as "similar enough" or similar enough could be decided later after looking at the first generation of the schedule.  Then beams grouped/re-grouped as the engineer sees fit and a subsequent generation of the schedule would yield smoother results and allow the engineer to consider factors of efficiency beyond simply weight of bars.

Once the schedule is generated and smoothed over beamslines as desired by the engineer, the resulting schedule would be a normal revit schedule but would be a beam schedule not a rebar schedule (We're not aiming to schedule individual rebar but the rebar that goes with a beam/beamline right?).  So the schedule could be adjusted as necessary to fine-tune.

Once the schedule is set, 3d rebar could be generated from the schedule and the "key" which is the customizable three span layout. 

I'd like gauge interest in seeing this type of solution brought to Revit Structure.

[Anonymous]

Just the crickets here...

If you think this is a crazy idea, that's good feedback too.  Any thoughts on rebar in Revit and where it could go would be welcomed.