Wednesday, October 22, 2014

Exporting pile foundations from Revit to FEM-Design


How to export pile foundations from Revit to FEM-Design?

In the current version of Revit StruXML Add-In (1.1.002) and FEM-Design (13.1.003) we do not support exporting piles or pile caps. It is simply because we can not handle analyzing or designing piles in FEM-Design yet. 

If it comes to foundations, we can only export foot pads, wall foundations and foundation slabs from Revit to FEM-Design (as those can be analyzed in FD). Here is some information of what we can do instead:

Export as supports
As we mentioned it in the manual, piles and pile caps can be exported only as  single support groups with the default setting "Hinged".
  

This solution however, has some disadvantages. To understand it fully, please have a look at the pictures below:
  • In this example there is a pile cap with 4 piles applied in the model. It is one of the standard families that can be loaded within a Revit Structure.
  • Let's look at the analytical model of the pile cap & piles. As it can be seen on figure below, the pile cap and each of the piles have a separate analytical model (even though they are applied as one instance), which is only a dot / point. According to my current knowledge there is no possibility of disabling the analytical model only for selected piles. We can only disable it completely for the whole instance (piles cap + piles), or enable it for all instance (pile cap + piles).
 


Due to this fact, when one exports a pile cap + piles as supports, a support will be added in each position of an analytical model. This is the way it is implemented and it fits well to any other foundation export. Finding a way around it just for sake of pile foundations export would certainly be possible, but we do not feel confident it would work well for all sorts of pile cap + piles types.


Bottom line, if one wants to export pile foundations just to get supports in FEM-Design, I would definitely recommend not to. Instead, one can really easily apply desired supports in FEM-Design simply by selecting all end points of columns. Much faster solution for pile foundations to be transformed to supports!

Export as columns

There are two solutions if one really wants to analyze pile foundations in FEM-Design: wait for another version of FEM-Design ;) - where hopefully those will be introduced, or remodel the pile foundations in Revit and export them to FEM-Design.

We were, and we will always be able to export structural floors and structural columns. These are relatively simple objects with rather obvious analytical model. And those two elements can be used to model a pile foundation that can be easily transferred to FEM-Design.
Have a look at this example:
  • Model a pile cap as structural floor element and piles as structural columns:
  •  This is how the analytical model looks now:

  •  Export to FEM-Design as floor and columns:


Voila!

If any of our users have a better solution, please share it with us. Leave a comment or write to iwona.budny(at)strusoft.com.