Way back in 2011 I wrote an article on the use of AutoCAD and Revit Structure to create a space truss structure. This was using AutoCAD meshes to facet a smooth lofted surface and then involved picking each line and converting these into structural members. At the time this was a valid workflow but, five years on and with the introduction of Dynamo we now have much quicker, productive and robust method to create 3D trusses or space frames.
In this tutorial I will just outline the main toolsets and processes used to create the above space truss. You will need the following software before you can attempt the tutorial:
- Autodesk Revit 2016
- Autodesk AutoCAD
- Autodesk Dynamo 9.1
- Lunchbox Package for Dynamo
The geometry is first created in AutoCAD as a polyline curve as shown below. The front curves are mirrored and then copied to the rear 50 meters back.
You can then create some arcs on the side of the roof structure and then create a lofted surface. Your AutoCAD model will then look similar to the below image.
The real fun then begins in Revit and Dynamo. Here is what the finished graph looks like! As you can see there won’t be scope to create a full, click by click tutorial on this but I will produce a video tutorial if there is enough demand!
The first step is to start a new Revit Structure project and start Dynamo. You then need to import the AutoCAD wireframe. I used the centre of the roof structure as the origin and inserted this Origin to Origin.
You then need to select this geometry in dynamo and then generate dynamo faces from the AutoCAD surface. The dynamo surfaces are then passed into the LunchBox Space Truss node. This creates all the line work and the faceting strategy for the top and bottom chords as well as the braces. Notice that you can also set the truss depth. I have chosen to utilise sliders for all these operations.
Once the centre lines are generated then you can start to assign structural members. This is done with the following. I have used a level to associate the members and then a structural framing type node to select different CHS members for each structural system.
The next step is to add some information into the members. I have set the Z justification to centre and also set some type comments so I can filter specific systems within Revit. Of course you could also number the members using dynamo as well!
You will then have a space truss. You can of course then edit the structure within AutoCAD and then the new members will generate.
All in all a much quicker and more productive workflow!