Revit Parameters

Revit has two sets of offset parameters that are useful for adjusting the location of structural framing geometry in 3D space relative to the analytical line - start/end level offsets and y/z offset values. This KB explains how Voxel Link uses (and doesn't use) these separate parameters.

  • Start/End Level Offset
    These two parameters, one for each end of the member, provide control over vertical elevation at the end of a member relative to the member's associated level. The two ends can be different thus allowing for sloping members.
  • y/z Offset Value
    These two parameters shift the location of the member shape or geometery off the analytical line of the element. Both values shift the shape perpendicular to the analytical line. The shape location is where Revit draws element  linework in plan and elevation.

RAM Structural Steel on the other hand, only models beam elements at their analytical location. There are no direct level offset or y/z type offsets available in RAM for framing members. You can, however, easily slope members in RAM by adjusting the top of columns on any level, not just the roof. For example, if you were designing a church with a large cantilevered mezzanine, you could drop the top of columns on the mezzanine level to accomplish the sloping floor. Of course, you can do a similar adjustment for a sloping roof.

Voxel Link Implementation

When importing from RAM, VL obtains the x, y, and z coordinate at each end of the framing member, computes the vertical offset from the associated level, and sets/updates the respective start/end level offset parameter at the end of the new/existing Revit element. RAM then is the source of truth for sloping members. If the sloping changes, make the adjustment in RAM, rerun, then update from RAM. The new elevations are automatically adjusted in Revit. 

What about a dropped terrace? There really isn't a good way to model this in RAM. You can create an additional level at the dropped terrace but these types of drops are typically 'small' and doing so can quickly confuse the P-delta lateral analysis in RAM. We have not found this to be an acceptable solution.

Instead, a best practice would be to utilize the y/z Offset Value in Revit. Model the terraced area in RAM with the other typical floor framing, then import normally into Revit. When the import has completed, adjust the z Offset Value to the terrace drop value, say -12". Voxel Link does not check/update the y/z Offset value so that adjustment is 'sticky' and never reset by Voxel Link.