Thursday, February 17, 2011

Revit - Working with Linked CAD Files

I have heard so many managers, engineers and technicians say that Revit can only be used on a Revit project, or we will only be using Revit on Revit projects. (In other words, we will only use Revit if the architect uses Revit)

My question is and always has been... Why can’t we as a structural design team use Revit on ALL buildings projects?

I don’t see any reason why we cannot use Revit on a project where the Architect is using AutoCAD (or any other 2D platform for that matter) Revit can be used to gain a competitive edge over other consultants, so why not commit and use Revit on all buildings projects, rather than following others in the design team?

Recently I put this to the test, and as long as you follow a few basic set up steps, things should run smoothly, this is a 7 step process that I generally follow.

1. Set up Grid Lines – Sit down with a printed paper copy (yes there is still room for some paper in this ever growing BIM / Digital environment) and set out your grid lines from the given dimensions on the drawing, left to right, top to bottom. Once your grid lines are set up, pin them in place.

2. Set up levels – Cut a long section and set up your floor levels (this could be FFL’s, SSL’s, or even TOS levels depending on your requirements and what information you have / want to show)

3. Link CAD Files – Set up default structural plans of each level, and link the Architectural CAD files into the appropriate level one by one, pinning each CAD file once it is positioned in the correct place on your Grid. (Grid lines to grid lines)


4. Begin to construct the model – Start by placing columns where they are required, setting the top and bottom levels of the column using the levels that were placed in step 2.


5. Continue constructing the model – carry out constructing the model, following on from the columns with floor plates, modelling each structural floor at the appropriate level, following an outline on the linked CAD files, or set out as shown on any architectural details.


6. Model Structural walls – Model any structural walls in the project, making sure they span between the appropriate levels.


7. Structural framing – What it says on the box...! Start to build your structural frame, now that the floor plates and walls are in, this should be simple.


Working with CAD files does have its disadvantages; the coordination process is very much a manual / visual process as working in 2D with CAD.

However, I feel like users can get a much greater understanding of a project if they build a Revit model from scratch, based on CAD files rather than using an architectural Revit model as a base.

The copy / monitor tool takes away the ‘construction process’ and as a result the user will know a little less about the building and how it fits together, relying very much on the architects model. I can construct a Revit model just as fast (if not faster) when working with CAD files, because I spend less time working out what the Architect has done and why parts of the model are ‘fudged....’

After working both ways on numerous occasions now, I have to say, in all honesty. Providing the communication within the overall design team is good, I would much rather work with CAD files.

3 comments:

  1. I have recently taken a class on Revit Architecture 2011, but I'm working with my old boss working on Revit Structure. Do you think I will need to have a formal training on revit structure to be able to work around it. I have used it yday and was able to work my way thru it except for a few things: Linking Architecture revit files to the new file i just created; and a very basic problem, making sure the beams are spaced evenly between columns b/c I know there is no divide command like in autocad. pls help...thanks!

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  2. The workflows in Revit Structure and Revit Architecture are more or less the same, so in response to your initial question, I see no need for any further training, the training is very basic anyway and project experience is the real way to learn Revit.

    As far as making sure beams are spaced evenly, place a dimesnion between the beams and click the EQ symbol, this will space them equally.

    Linking models, if you have been on a Revit Architecture course, the linking of models is the same process regardless of the discipline, so that is something you should of learned.

    Failing that, follow these steps

    http://docs.autodesk.com/REVIT/2010/ENU/Revit%20Architecture%202010%20Users%20Guide/RAC/index.html?url=WS1a9193826455f5ff1955f1510a86ab16de-57e6.htm,topicNumber=d0e107826

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  3. Good Article. You hit the nail on the head, I find it easier not to fool with the size and visibility issues that come with revit architecture files. There are definitely some advantages to having the arch file, but you can get many of the same benefits of revit without it

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