Mono Truss with LVL Bearing issues

[Buzter]

Revit Structure 2009

I am currently working on a project where there is an LVL (flush, or upset into the trusses) at mid span and they will be using mono trusses for the job, it is on the hip of the roof. I have made a family for the truss incorporating the LVL. It seems to come in fine, but when I try and modify the truss, it gets all jacked up. Any help would be appreciated, I have uploaded a screen shot of what I get, the actual truss design, and also the truss family.

[Craig_L]

I had a quick look at your family, I hate truss families, they always make my brain bleed.
However I am confused as to how you even achieved a sloped top chord at all as yours appears to be one continuous member and without a variable to set roof slope at all.
You could try putting in some formulae so that it computes your top chord angles based on your other contraints (vertical from left to right vs truss height for example) this may force the correct slope for you.
Otherwise as a longer work around you could split the truss into 3 segments, left, centrepiece and right. Not really a lot more work and would give you a much easier manipulated result....but I guess not really preferable.

[benmay]

Hi, You cant really get the current family you have there to flex properly. You would need to add at least 2 additional parameters for the spacing of points 3 & 5 which could be flexed separatly to the overall length of the truss

From there you could constrain the diagonals to reference planes intermeadiatly with out too much trouble.

You would also be best to build in a parameter for the roof pitch, as just editing the top profile will not really work for this type of truss (although you might get it to work in a small amount of cases)

To be honest, with these sort of things you need to decide how many of them you need to model, and whether it needs to be parametric. If you are creating them all them all the time, spend some time to create a good parametric truss family, but if they are few and far between you would be best to just create a one off family with the structural framing family

The other downside of trusses, is they wont automatically clean up the connections, and that looks pretty average in section for timber truss, as you want to see nice mitre/butt joints so you end up spending forever coping each member

Happy to help further if you want to try making a fully parametric version