beam problem

[cheukling125525.110216]

I attached a beam family file here.
My wish is to make a 200x400 taper at the bottom side of
a rectangular beam.
I have set up two parameters to control the void dimensions
and tried to flex the model in the rfa, everything okay.
But when I load it to a project file, the taper will always appears
at the middle span of the beam, no matter what length is the beam
I placed. Why ?? Should it always stick to the right hand side
as I set up in the family file ?

Anyone can help on this ?

thanks

[Paul Andersen]

Cheuk, I finally had a few minutes to check out your family and I found a few things.

Your family was missing a beam depth parameter so I added one.

The profile you were using for the beam sweep did not have its Width and Depth parameters tied to the corresponding parameters in your family so your beam could not flex properly. If you expand the Families tree in your project browser to expose the B2 profile and right click properties you will see the Type Properties dialog for this profile. By clicking the little square box at the end of the Width and Depth parameters you can link them to the corresponding parameters in your family.

I added a reference plane 13mm off of the member right reference plane (similar to the opposite end) and constrained it to the graphical end of the member. I believe this extension is used to facilitate cleanup with other concrete members and could be done away with if you wish by constraining the beam sweep's path to the member right reference plane.

Finally, I constrained the void extrusion's horizontal and vertical legs of the sketch to their corresponding reference planes and their endpoints to the dimensioned reference planes (Dim H and Dim Y). After finishing the sketch I constrained the depth of the void extrusion to the beam width reference planes. The Dim H and Dim Y dimensions and reference planes can be kept inside the void extrusions sketch as you originally had them as opposed to outside as I have them if you don't plan on leveraging them for any other purpose in your family. On a less complex family such as this it probably makes sense to put them inside the sketch. In general I usually layout, dimension and flex all of my reference planes prior to adding sweeps, extrusions, etc. It also never fails that as soon as I bury these I end up needing them for something else later on.

The only other thing that I noticed is that you had a couple of reference planes pinned which isn't really necessary.

[Cheuk Ling]

Paul ,
sorry for late response as I was mega busy these days
on my works.

I created this family starting from the factory template :
Metric Structural Framing - Beams and Braces.rft,
I'm quite sure no 13mm ref planes offset from both ends
of the geometry included in it.
Same as the factory beam family ,M_Concrete-Rectangular Beam.rfa,
no such two reference planes found.
Just wonder If they are crucial for controlling the coping behaviour
for beam junctions, why not provided ?

Is it without this two reference planes will make the bottom taper
(= void length) extend to the middle of the beam when placing into
a project file ?


However, thanks for pointing out my mistakes and correcting the
family file for me. I think I have got the correct / common practice
of producing such kind of family.

Please note that we don't have enough training resources here
provided by Adesk, all technique my co-workers and I gained is
mainly by surfing the tutorial and help document, or learned from
those factory template files , so doing silly things or
misunderstanding something are unavoidable.
Lastly, applying wrong pins to some ref planes is that I got difficulty in
controlling the movement of them when changing parameters.
I have submitted another thread "Refence plan behaviour"
asking for that and is awaiting reply.

Thanks again for your amended family file, I will use it in my job.

regards

[Paul Andersen]

I created this family starting from the factory template :
Metric Structural Framing - Beams and Braces.rft,
I'm quite sure no 13mm ref planes offset from both ends
of the geometry included in it.
Same as the factory beam family ,M_Concrete-Rectangular Beam.rfa,
no such two reference planes found.
Just wonder If they are crucial for controlling the coping behaviour
for beam junctions, why not provided ?

Is it without this two reference planes will make the bottom taper
(= void length) extend to the middle of the beam when placing into
a project file ?
Cheuk, you are correct in that the Metric Structural Framing - Beams and Braces.rft does not have the additional reference planes on either end. This is probably due to the fact that this is a base framing template for all materials. As you start to build more families you may want to consider developing or adding to these stock templates or start with a copy of the delivered content that is similar to save some time. Family templates are really just .rfa files that you manually change the extension to .rft.

Perhaps your content is different with regards to the M_Concrete-Rectangular Beam.rfa but if you look at Floor Plans -> Ref. Levels View you may be able to see the additional reference lines at each end constrained by the 13mm dimensions. They are harder to see in the default front view because they do not extend above or below the beam. I haven't had a chance to test whether or not these are necessary so I'm just guessing that it's to aid with clean-up. You could certainly do away with the one at the taper end and constrain the void and graphical end of the beam to the member right reference plane. In fact this may be the way to go if you are using this for cantilevered ends as dimensioning the length of the member as I have it will probably result being 13mm too long.

[Cheuk Ling]

Paul,

Again, your estimation is absolutely correct.
Removing the 13mm constraint at the taper end will result in
1. the beam stops at the support edge (may be a beam or wall or column face)
with a gap of 12.9mm.
2. the taper position show up at the middle of the beam instead of
the designed dimension set up in the family.
(this behaviour is a bit hard to understand.)

Best wishes
Cheuk

[Paul Andersen]

Cheuk, I did some further testing and it appears that all framing members of the following material types: Concrete, Other, Precast Concrete and Steel, are designed to automatically hold back the physical / graphical end of the member 1/2" (13mm) from the face of columns, walls, etc. unless purposely built not to. In the case of the delivered concrete framing members and the _Taperbeam family I previously posted a constrained 1/2" (13mm) extension beyond the member end reference planes is required to close this gap. Framing members of the Wood material type seem to be the only ones that do not behave in this manner.

I've attached a revised _Taperbeam_No Extension family that has this extension removed on the tapered end in case this works better for your intended application.

[Cheuk Ling]

Hi, Paul

thanks for your findings and the attached file which is exactly
what I needed.
Just want to add one complement.
If you changed the Structural material to "Other", and then loaded
the beam into a project file, it could be freely cut by ref plane,
but the disadvantage is that all beam joints won't be automatically
clean up even with equal beam depth.
Only applying "concrete" can have the automatical join function,
however, it can't be cut freely by ref plane then.
So , I normally use "concrete" in most cases, and only use "Other"
for beams end at different shapes.

Good luck
Cheuk

[radu.grosu]

Hy, I'm having a hard time with beams in Revit as well. No matter the beam family I use (I generally use simple rectangular cross section monolithic concrete beams), in certain cases, the beams connect to the walls and the other beams perpendicular to the joint by them selves even if I stop them at the face of the wall, and the result is total horror. The join has the most unfortunate shapes, never though the clean join I would expect. I tried all possible tricks and could not escape this. Is there any possibility to disallow join for beams?

[Cheuk Ling]

As I experienced , changing the structural material type from concrete
to other would disable the automatically join function of beams.
Of course , I don't expect to use tricks to solve such kind of problems
as one may have over thousands of beam junctions in a project.