Revit Structure

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Distinguished Contributor
bjur
Posts: 158
Registered: ‎09-14-2011
Message 1 of 12 (500 Views)

Face based families move when adjusting beam extensions

500 Views, 11 Replies
12-04-2012 10:12 PM

I have a major issue that I've been struggling with all day.  I have been modeling shear tabs and stiffener plates for my beam connections.  I have attached a few pictures showing the face based families (stiffener plate and shear tab) in their correct position prior to adjusting the "End Extension" property of the Wide Flange object in my model.  Once I adjust the "End Extension" property, the sheartab and stiffener plate (both face based families attached to the beam web) move by the same amount as the extension.  This is a major bug in my opinion as I don't want revit moving stuff that I place in a particular spot.  Why is it doing this and how do I make it stop.

Distinguished Contributor
bjur
Posts: 158
Registered: ‎09-14-2011
Message 2 of 12 (493 Views)

Re: Face based families move when adjusting beam extensions

12-04-2012 10:20 PM in reply to: bjur

I just verified that this only happens if I modify the "End Extension" property.  The "Start Extension" property does not make the hosted families move.

Active Contributor
kentw
Posts: 32
Registered: ‎05-14-2012
Message 3 of 12 (487 Views)

Re: Face based families move when adjusting beam extensions

12-04-2012 10:57 PM in reply to: bjur

A work around is to align and lock the shear tab to the joining beam, then to pin the joining beam so it will not move.  I'll see if I can come up with an actual solution.

 

Interestingly just pinning the shear tab does not keep it in the correct position

 

 

_________________________________________________________________

KarelCAD Application Support Specialist
Distinguished Contributor
bjur
Posts: 158
Registered: ‎09-14-2011
Message 4 of 12 (472 Views)

Re: Face based families move when adjusting beam extensions

12-05-2012 11:26 AM in reply to: bjur

I hadn't thought about pinning the beams in place.  This does "work"....but I think this is a bug that needs to be fixed.  I can see the benifit to walls stretching when other walls are moved...but when objects are placed in a particular spot, I don't like it when they move on their own, unless I set a locked dimension or relationship where I explicitly tell Revit to move object A when I adjust object B.  I'm working on doing full shop drawings in Revit and this bug is a borderline deal breaker.  Thanks again for the workaround.  Is there any issue with locking hundreds of objects in a model.  Will this backfire and blow up at some point?  The only thing I have ever locked in place is a cad drawing that I used for an underlay.

Distinguished Contributor
bjur
Posts: 158
Registered: ‎09-14-2011
Message 5 of 12 (467 Views)

Re: Face based families move when adjusting beam extensions

12-05-2012 11:36 AM in reply to: kentw

Attached is the file where this bug occures.  Play with the end extensions on the beam and see what happens.  I had to delete the second beam to get the file size small enough.  The stiffener is still in the model and will move when the beam  end extension property is changed.

Active Contributor
kentw
Posts: 32
Registered: ‎05-14-2012
Message 6 of 12 (460 Views)

Re: Face based families move when adjusting beam extensions

12-05-2012 03:51 PM in reply to: bjur

I agree that this should be logged to Autodesk as an issue.  To do this either log the issue to your Autodesk Reseller or submit the issue to Autodesk via the subscription centre

 

http://www.youtube.com/watch?v=GrJ2H6cOJ2c

 

I have tried rebuilding the geometry in the family using various methods all giving the same result.

 

 

_________________________________________________________________

KarelCAD Application Support Specialist
Employee
Joe.Charpentier
Posts: 938
Registered: ‎02-28-2006
Message 7 of 12 (449 Views)

Re: Face based families move when adjusting beam extensions

12-06-2012 08:56 AM in reply to: bjur

You are hosting this to the face of the "supporting" beam, correct?

When you adjust the length of the beam using the end adjustments, you are modifying the face that the element is hosted on.

 

While I agree that the difference in behavior between modifying the start or end of the beam is somewhat arbitrary, in the absence of any constraints Revit has to do something when the model is modified.

 

Personally, I wouldn't use any pinning.

I'd simply constrain the side of the connection plate to the face of the beamweb  that it is supporting.

That way, it is always exactly where it is supposed to be.

Of course, angular movements of the beam (slope/incline or rotation from perpendicular) will require you to reconstrain these, but that is a general limitation of Revit's constraints.

 

Joe

 

Distinguished Contributor
bjur
Posts: 158
Registered: ‎09-14-2011
Message 8 of 12 (442 Views)

Re: Face based families move when adjusting beam extensions

12-06-2012 09:51 AM in reply to: Joe.Charpentier

I am using the "supporting" steel beam web as a host.  Anything hosted on any face of the beam will move if I adjust the end extension property of the beam or physically move the end of the beam any distance.  The start of the beam and start extension property have no effect on anything hosted by the beam.

 

Why whould revit have to move anything with respect to the ends of the beam.  When the beam as a whole is moved, then the objects hosted by it move along with it.  That said, when the beam is stretched, the objects hosted by the beam should stay put.  This would be like haveing a door move in a wall just because you extended the wall.  Or having lights hosted by a ceiling move just because you made the ceiling bigger.

 

Here's where things get really wierd...If I lock the stiffener to the face of the SUPPORTED beam (not the beam that is hosting the stiffener) and then adjust the end of the SUPPORTING beam, the SUPPORTED beam will move.  No good.  Again adjusting the start of the SUPPORTING beam has no effect.

 

I'm betting somewhere in the code, the location of the hosted elements are based on the end of the beam, thus when the end is modified, the hosted elements move.  No good.

Distinguished Contributor
bjur
Posts: 158
Registered: ‎09-14-2011
Message 9 of 12 (439 Views)

Re: Face based families move when adjusting beam extensions

12-06-2012 09:58 AM in reply to: Joe.Charpentier

Here's some screen shots:

 

I adjusted the end of the SUPPORTING beam 10" with the "End Extension" properrty.  The shear tab on the SUPPORTED beam is hosted by the SUPPORTED beam, thus it did not move.  However, the stiffener on the other side moved 10 inches, just like everything else.

Employee
Joe.Charpentier
Posts: 938
Registered: ‎02-28-2006
Message 10 of 12 (427 Views)

Re: Face based families move when adjusting beam extensions

12-06-2012 11:21 AM in reply to: bjur

OK, I see what you are saying- the face-based components on beams don't behave the same way that they do on walls.  The "supported" beam certainly shouldn't be pushed around by the constraint to the face-based component.

 

Thanks for documenting the issue for us.

 

It seems like the workaround is that you should host your connection hardware on the supported element, not on the supporting element, so that you don't experience any unexpected movement.

 

Regards,

Joe

 

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