Truss bottom-web chord connection problem

[Anonymous]

Hey everyone, 

I am currently working on creating an old barn building Steel Structural Framing. The roof of this building is made of multiple truss systems. As you might be know, the truss system in Revit 2019 does not come with the beam-beam and/or beam-column connections. So far, i have been installing the steel connections between the top/web/bottom chords and whatever two or more items meet. Although this might seem easy, changing the bottom chord to Double C Channel will end up rejecting the connection between this bottom chord and the web chords. How to have this type of bottom beam type and at the same time will have all the steel connections installed ? 

Thanks in advance 

[catalin_lang]

Compound elements, like Double C Channel, are not supported as input for structural steel connections.

More information about supported elements for steel fabrication workflow can be found here.

It is a known limitation.

[YarUnderoaker]

You may use workaround - create separate elements for double section. For example, copy channel at same place and set Cross-Section Rotation value to 180 and justification. Then connect column to bottom chord (one of element and adjust cutback to other). This is not completely parametric but works. 

[Anonymous]

thanks, i actually have done that. but do you think that will affect the structural analysis when we do it? i mean when we do the structural analysis in Revit inviroment and even when we export to Robot! will that be ok ? What i have done is that i use the C channel beam which Revit support and then i mirroried at the same axis so now i have a "double c channel " shape of a beam, and use it the bolt command and plate command to connect the web beams and the two c channel beams together, is that ok in terms of analysing the loads on the structural system of this building? 

[YarUnderoaker]

Yep, this is not good for structural analisys. You must manualy change section in Robot and delete overlaped bars.

[Anonymous]

will you be able to have double c channel beams in Robot? what is the procedure to change that , i am a beginner at Robot

[YarUnderoaker · Accepted solution]

Yes, Robot has different type of double sections and can check it.

[Anonymous]

Thanks