Revit Space Trusses using AutoCAD and Dynamo

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.

Revit Strcuture Roof Geometry

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.

AutoCAD Roof Profile

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.

AutoCAD Geometry.jpg

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!

Dynamo Graph

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.

Dynamo Graph - Selecting the AutoCAD geometry

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.

Dynamo Graph - Adding Structural Framing to the curves

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!

Dynamo Graph - Setting the instance parameters for the structural framing.jpg

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!


Revit Structure Tutorial – Attaching Structural Objects Together

When modelling Structural objects such as walls, columns and trusses it is sometimes very useful to attach the top or bottom of these elements to other structural objects such as roofs, floor slabs and foundations etc. This technique will maintain a parametric relationship between the elements and accommodate edits such as slope and elevation.

Attach Top Base Columns and Walls

You can attach the following families to the references in the table below:

Revit Attach Top Base table

We will start by looking at attaching structural columns to Floors.

In-Situ Concrete Column to Floor

Select a column and then click Attach Top/Base from the Context panel as shown below.

Attach Top Base on Contect panel

On the Options Bar below the Ribbon you will see the followingOptions Bar - Columns

You can of course attach either the Top or the Bottom of the column to a floor slab, the attachment Justification allows for the following processing of the In Situ Concrete columns:

Revit In Situ Column Join options

As you can see the in Situ Concrete members will join as expected but the Steel, Timber and Precast columns will prove more problematic. These columns will not cut and a Reference plane will need to be utilised to create the required detail.

Revit Steel Column Join options

If a Structural Column is attached to a non-structural target such as a roof or ceiling then you will see the following warning, the column is still attached but the analytical model will have no connectivity and behave like a mast!

Error - Non-Structural Target

Walls have a similar workflow where you can attach either the top or base of a wall to a roof, floor, ceiling or another vertical wall. The below image shows a simple example of attaching a block work wall to two structural slabs.

Attach Wall to Floor

Things can get a little more challenging where you have a situation as shown below where your wall needs to attach to the underside of a beam. In this situation you will need to select the wall and then edit the profile and then use the pick lines tool to create the required geometry.

Revit Pick lines to edit wall profile

Also note that if you edit the profile of a wall then this will disassociate the constraints that the Attach Top/Base command adds.

Trusses can be attached to roofs and floors and enables the user to attach the top or bottom boom to various floor shapes. The below example shows a steel truss with the top chord attached to a sloping floor.

Revit - Steel Truss

Here are some more examples with a timber truss attached to a roof and a steel truss attached to a roof that was created as an extrusion.

Revit Roof with Trusses Attached

If the Top and Bottom chord are drastically different then you may have to make use of the Edit Profile tool on the contextual ribbon. This allows the user to create a sketch for both the top and the bottom chords. Also notice that once the truss has been created you can effectively ‘explode’ the truss to structural framing with the Remove Truss Family command.

Revit - modify Truss Ribbon






Revit 2015 – Structural Framing Enhancements

This will be a very interesting year with regards to steel detailing, fabrication and Autodesk software. A few months back Autodesk purchased Graitec Advance Steel and Advance Concrete to extend their offering in the steel detailing & fabrication industry. The only other Autodesk product was AutoCAD Structural Detailing which I would imagine will start to disappear from the various Autodesk suites that included this as there have been very few developments with this software for the past couple of years

Revit 2015 Splash Screen

This year Revit 2015 has seem some great interface improvements with regards to the justification points on steel and precast members and member offsets. We will begin by looking at the justification point tool.

Revit 2015 - Justification Points

This is essentially an ease of use improvement to an existing set of tools to offset steel, timber or precast member both laterally or vertically from the original position to predefined points. This will only reposition the physical position of the member and leave the analytical model unchanged.  The tool can be used equally well in plan, elevation and sections as well as 3D views.

Revit 2015 - Beam Justification points

The offset command will reposition the framing member graphically in the Y and Z axis. This is a much easier way of offsetting the structural framing members.

Revit 2015 - Y and Z graphical Offset


The change Reference tool is perhaps my favourite new framing tool in Revit 2015, this tool allows the user to select a new reference for the end of a joined beam and then cycle between these references by using the Change Reference command. See the image below.

Revit 2015 - Picked Reference on Structural FramingRevit 2015 - Change Reference

Another interesting feature is an existing tool from Revit 2013, the humble shape handle. For those of you that didn’t use Revit 2013 or earlier releases the shape handles allowed a steel, precast or timber framing member to have its physical length changed graphically. Revit 2014 omitted this tool and instead relied on the user inputting values into the Properties Palette which was slightly frustrating!

Revit 2015 - Shape Handles

Structural Framing members can now also carry more information about the members physical dimension as well as analysis properties. Each Framing family now has a new category called Section Shape Property.

Revit 2015 - New Section Shape parameter

Once again I will create a detailed tutorial video on these features when I have access to the final shipping release of Revit 2015.



Revit Structure 2014 Tutorial – Shared Parameters, Schedules and Tags

In this tutorial we will look at the advantages of creating Revit families that utilise shared parameters rather than project parameters. Project parameters are fairly flexible and allow the user to create any information required and attach this information to many Revit objects and categories; however, you cannot tag or schedule this data which can of course be a big limitation. In this simple example we will look at a rectangular pad foundation. We will first modify the family, then create some shared parameters and then use this within a project.

  1. Start a new Structural project and then place a few default rectangular footings on Level 1 as shown below.Isolated Foundation - Pad Foundation
  2. . Select one of the Rectangular Footings and then edit the family from the mode panel as shown below.  

Modify Structural Foundations

3. On the Manage Ribbon select the shared parameter command as shown below.

Shared Parameter Icon

4. Create a new shared parameter file and save it to your desktop. Name the Shared Parameter file Foundations. (Note that you would normally save this somewhere safe for future reference but for this exercise the desktops fine.)Edit Shared Parameters Dialog Box

5. Create a new Group and Call the group Foundation Dims as shown below. By using groups this keeps our shared parameters neatly organised.Shared Parameter Dialog - New Group

6. Create a new parameter called Foundation Length as shown below. Ensure that the Discipline is set to Common and the Type of Parameter is set to Length as we are going to use this to control the Pad Foundation’s Length. Click OK

New Shared Parameter

7. Repeat these steps and create a further two parameters called Foundation Width and Foundation Thickness. Your Edit Shared Parameters Dialog should now look like the image below. Click OK

Completed Shared Parameters Dialog

8. Next you assign these new Shared Parameters to the dimensions controlling the Pad Foundation. Open the Floor Plans – Ref.Level to display the foundation in Plan as shown below.

Foundation Plan - Ref Level

9. Select the Length Dimension and then click edit Label from the pull down menu on the Options Bar as shown below.Pick Dimensions and add Label

10. In the Parameter Properties Dialog box select the Shared parameter option, ensure that the Type option is selected and that the Group parameter under option is set to Dimension (this is the default). Click the Select button to choose the Shared Parameter. Pick the Foundation Length Parameter and click OK. Also Click OK on the Parameter Properties Dialog.Parameter Properties Dialog Box

11. Repeat steps 9 & 10 for the Foundation Width Parameter by clicking the Width Parameter and replacing this with the Foundation Width.

12. Open the Front View by expanding Elevation on the Project Browser and repeat the above steps for the Foundation Thickness parameter.Foundation Thickness Parameter

13. On the Create Ribbon select the Family Types icon as shown below.Family Types Icon

Review the parameters within the Family Types dialog; it should now look like the image below.Family Types DialogYou will also notice that the Structural Material in the Materials and Finishes group is currently an instance parameter meaning that each pad foundation could have a different grade of concrete. It’s recommended to change this to a Type Parameter for ease of use. Click the Modify Button and swap the parameter from Instance to Type. Change Material from Instance to Type

12. Save your new family as Pad Foundation.Rfa in a location of your choice.

13. Click the Load into Project command to load the family into our project as shown_below.Load Into Project Icon

14. You should now be back in your project and have the Pad Foundation at your cursor location. Place a few pads on the Level 1 plan.

15. Next you add tags to the Pad Foundations that you have placed. On the Annotate Ribbon, click the Tag by Category command and place tags on the pad foundations as shown below.

Add tags to the Pad Foundations

You will notice that the default tag is reading the Type Name. This can be dangerous as the user could change the Foundation size but not update the Type Name. We will now edit the default tag to read the Length, Width and Thickness of our foundations.

16. Select one of your Foundation Tags and click edit family on the ribbon as shown below.Edit Foundation tag

17. You will now be editing the default Foundation Tag. You will see the ‘1t’ which is the sample text for the label. Select the ‘1t’ and click the Edit Label command as shown below.Edit Label

18. Next you add the Shared Parameters to the Edit Label Dialog Box. You will notice that the list of parameters does not include the three Shared Parameters that you previously created. Click the New Parameter icon in the bottom left of the dialog box to add the Shared Parameters. You now pick the Select Button and add your Shared Parameter ‘Foundation Length’. Click OK twice to return to the Edit Label Dialog.Add Shared Parameter for labels

Repeat the above steps to add the remaining two shared parameters. Your Edit Label dialog should look similar to the below image.

Edit Label Dialog After Shared Parameters Entered

19. You now add the Shared Parameters to the Right hand panel to compose the label. You will notice that the Foundation Thickness parameter has a duplicate entry. (Note that Revit has a bug which allows to Parameters of the same name to exists.) Make sure that you add the parameter that shows the edit icon as shown below, the other label will cause the edit button to grey out as this is the default parameter.

Foundation Thickness SP Bug

20. Configure the Edit Label dialog with the following settings. This will ensure that our new tag reads <Foundation Length>x<Foundation Width>x<Foundation Thickness>. If you require any data on a new line then select the break option by ticking the relevant box. Click OK when finished.

Label Configuration Dialog

21. Drag the Labels grip to control the text wrapping as shown below and then Load this family into your active project as shown below. (Note that if you see the Load into Projects Dialog Box then choose your project and not the Pad Foundation)

Drag Label and load into Project

22. Click over write the existing version and you will notice that your foundation tags now show the Length, Width and Foundation Thickness. Experiment by editing and creating new types of your Pad Foundation and note that the tags always show the correct information.


TIP: If you want to change the Pad Foundation Type then select a Pad Foundation, Click the Tag and then add your required sizes into the dialog as shown below.Control Foundation Type by changing the label

Continue the exercise by creating a Structural Foundation Schedule of your choice. Note that your Shared Parameters are in the available fields by default.






I hope that you enjoy this tutorial, If you have any ideas or requests for further topics or subjects then add a comment.


Revit Structure Tutorial – Site Setting Out

In this tutorial we will explore the techniques and tools used to successfully coordinate a Revit project to a survey or OS grid. This process is often neglected which will cost you dearly later on! The problem is that this is only done once at the start of a project so is easily forgotten. A primary consideration is preparing a CAD file so that it is suitable for import into Revit. See Step 1! Get this wrong and the whole process will fail.

 Link to YouTube Tutorial :

Revit Site

In a later tutorial I will outline the process of coordinating with Autodesk Civil 3D and a 3D TOPO but in this tutorial we will concentrate on a 2D survey, this could of course be in a variety of formats such as DWG, DGN or DXF.

1. The first step is to prepare your incoming CAD data for use within Revit. This will involve checking the UNITS of the CAD file (i.e. millimetres or metres), accuracy of the drawing and the layer configuration. If you have a very large survey then I would recommend using the WBLOCK command to select the relevant data and saving as a different name, this will clip a very large file. You will also need to check the extents of the file, if any data is outside your limits then delete (must not be greater than 20 Miles). At this point, freeze or turn off any layers that you do not want to be visible in Revit

AutoCAD - Preparing the survey drawing2. It is advisable to clearly mark a primary agreed setting out point on the CAD file that can be seen in Revit. This should normally be on a grid intersection and agreed and used by all Revit Buildings and disciplines (Construction, Architecture, Structure & MEP). If you know the consultants, architects and contractors who you are working with try and set up a Revit coordination meeting before any major modelling goes ahead to agree a universal setting out point that all Revit Buildings and models will use.

You can also create a secondary SOP for verification purposes. This should include the Easting, Northing and a level as shown below. If the structure is fairly large then you can consider increasing the precision of the coordinates. This is particularly useful for rotational errors that may occur.

Save the CAD file.

SOP1 setting out point - CAD

3. You are now ready to import the CAD file into Revit Structure. Once the CAD file has been selected you will need to configure the various setting within the dialog box. In most cases you will want to preserve the colours. Set the Layers/Levels to Visible and this will import only the CAD data that is on. Make sure that the units are set to the survey units, i.e. if the original CAD drawing is in Metres set the Import to Metres. The positioning should always be set to Auto – Centre to Centre. This will place the centroid of the CAD Building directly into the centre of the Revit Building (Note that this must not exceed 20 miles).

Revit Cad Link4. You will now move the CAD file to the Revit datum (0,0,0) position. The Project Base point will need to be visible; in the visibility graphics dialog box check the Site Category and then check the Project Base Point sub category.

Revit - Project Base Point

Once you have moved the survey your Building will look similar to the image below. Note that the project Base Point is now at the agreed setting out point (Some contractors may want to use the local agreed coordinate system on large sites for piling etc.)

Move the Survey to Project Base Point

You now set the Revit Site coordinates to match the CAD survey. Click the Manage Tab, Project Location, and Specify Coordinates at Point and select the Project Base Point. Enter the Easting’s, Northings and Elevation.

Set Coordinates


5. Save the Revit Building as the ‘Site File’. You will later insert your Revit Buildings into this file and acquire the coordinates.

6. You now prepare the Building file. Create a new Revit project with your active template and then make the Site Plan current view.

Revit Site Plan

Using Visibility/Graphic command (VV) switch on the Project Base Point.

7. If you have a DWG with the grid and architectural features then import this into the current view using the same rules as when importing the site plan. Move the Building to the agreed setting out point (Grid Intersection). Add a Spot Coordinate to the project base point, this should read 0,0

Model on Agreed Grid Intersection

8. Save the project as the Building File (e.g. Building A)

9. Open the Revit Site File and then import the Revit Building File by selecting the Insert Ribbon and then the Link Revit command as shown below.

Link Revit File

The Linked Revit File will now appear in the centre of your site file. Move and rotate the file to the Project Base Point to match the setting out of the grid. If you are new to this procedure then be sure to watch the tutorial video.

10. You will now acquire the coordinates from the Site file and record these into the Building file. Select your linked Revit file and in the Properties Window click the Not Shared button as shown below.

Select Linked Building File

Once the Not Shared button is clicked you will see the Share Coordinates dialog box. Use the first option which will publish the Shared coordinate system of our site file into the Building file.

Share Coordinates - Publish

11. Close the Site File and Open the Building File. You will see a dialog box asking if you want to save changes, click yes.

12. Open your Building file and return to the Site Plan. You should now see the correct coordinate system and if you change the Orientation from Project North to True North you will see the Building rotate to a True North position.

Building File - Coordinates12. Because the Revit Building file is linked, if the Building file is moved within the Site file then this will be ‘pushed back’ to the Building file and all coordinates and levels will be updated.

Tips and Tricks

Don’t forget to change your Levels to Survey. This will ensure that your project levels are always synced to the Site. Any changes to the site will instantly update the Building files.

Levels set to Survey

Don’t forget to watch the Tutorial Video, a lot to take in!


Revit Structure 2013 to Robot Structural Analysis Professional 2013

Link to Youtube Video :

With the release of the Building Design Suite Ultimate 2013, many of you will now have access to Autodesk Robot Structural Analysis Professional 2013. I thought I would spend a little time looking at the interface between Revit and Robot and also checking out some of the transfer options and how they work with the Revit 2013 release.

In older releases the transfer option from Revit to Robot was located on the extensions ribbon but this is now found on the Analysis ribbon along with the analyse in cloud option with Autodesk 360. The interface is surprisingly simple to use and the transfer works very well providing you model the structure correctly within Revit Structure. Some of the biggest issues I have found with the transfer and subsequent analysis have been that the analytical model has not been suitably edited and the tolerances were not set correctly.

 Above you can see the Analyse Ribbon in Revit Structure 2013 with the tool to send the structure to Robot Structural Analysis Professional 2013.

Once you have selected the Robot Structural Analysis link then you will see the Integration dialog box. This enables you to send and also update the model from Robot. You can even transfer the Revit Structure model to a Robot Analysis file (.rtd) if you do not have Robot installed on your PC.

The send Options allow access to some further tools that can really make a difference to the way that Revit Structure transfers a model to RSA. You can see below that the self weight of the structure can be mapped to a Dead Load and the Bar end releases can be read from Revit or ignored. The option to use a curtain wall and mullions as panels is quite an interesting option but this only works for curtain walls drawn as walls within Revit. You can also see that stray nodes and inconstancies can be corrected with the Execute model correction tool.

Once the structure has been transferred the analysis can be run within Robot. The return of the data back into Revit Structure needs to be carefully considered as the technician is likely to be working on the structure while the engineer is making changes and the model can easily become unsynchronised.

I have also tested the transfer of connections from Robot to Revit and this works well but just for end plate to column flange connections. Robot is capable of designing the connection based on the loads from the analysis, then you can tweek and edits the sizes of plates, bolts etc and then transfer this back into Revit to form part of the documentation. I expect that this is an area that Autodesk will focus on in the future and Revit Structure will likely become a tool capable of producing the fabrication drawings and documentation.

If any of you find this interesting then I can make a tutorial video if there is enough interest.


AutoCAD Structural Detailing – Steel Fabrication Drawings Tutorial

Link to YouTube Video:

Many of you have probably had a dabble with AutoCAD Structural Detailing and placed a few 3D connections on a steel structure using the automated macros and not really taken it any further! The process of creating fabrication drawings is surprisingly fast and efficient providing you have a good set of templates and a basic understanding of the workflow.

In this tutorial I thought I would share the process of going from a 3D ASD model to finished fabrication drawings. We will be looking at the following features:

  • Element Positioning – The process of assigning unique marks to each object.
  • Grouping – Organising objects into assemblies
  • Using Templates
  • Creating Printouts


Link to YouTube Video: