Post Tension Structures in Revit continued: 5-point bars and path hosting

PT slab 5-pointAfter the last post on post tension bars in Revit I received some positive feedback and questions about how one would go ahead and add more points. You can do this by simply copying the intermediate point(s) around and re-hosting, followed by a new hosted circle and sweep.PT bars 5-point

Now, when changing between 3-, and 5-point tendon families we encounter some challenges with the Adaptive Point Numbers. Every time Revit has to generate new points, like when you change from a 3-point PT tendon to a 5-point, it will use the default placement in the family rather than something that would seem more appropriate to you. And is you change back from 5 to 3, Revit will shorten the tendon, because Adaptive Point Number 3 is not the end number in the 5-point family.

You can solve this by changing the intermediate points to Shape Handle Points instead of Placement Points in the Family Editor. Doing this the end points will always remain number 1 and 2, and the tendon span length will remain constant. The intermediate shape handle points will still jump around, but you get less modifying to deal with.

PT bar 5-point

Download the new 5-point PT bar from Content.

PT slab 5-point surface perspectivePlaying around with more and more points you inevitably start to wonder if there are cooler ways of modeling the whole shebang. Indeed there are. Once you have Adaptive Points to play with it’s fairly simple to host these on as many divided paths as there are points.

PT mass divided paths

Because most post tension tendons only curve vertically, you want to make sure the divided path points that host the PT tendon Adaptive Points always form a plane. This is not always the case when you start messing around with curves as the point locations are often a product of the path length, which in turn varies depending on the curvature. You can override this, and have all points in one plane, by using the Intersect tool and Reference Planes.

PT mass divided paths with refplanes

In the example used here I’ve made 5 3-point splines, where 3 of them form vertical curves. With these I can control the entire vertical layout of the now organic post tension structure parametrically. Please note that this of course does not work if you’ve changed the intermediate points to Shape Handle Points. They need to remain Placement Points.

PT massDownload the sample PT mass family from Content.

PT slab 5-point surface closeup

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s