Beam system frustrations

[dbaldacchino]

I am modeling an existing structure (RB 9.1) and have noticed that if the number of joists is even, it's a royal pain to get the beam system in the right place. I have not had a problem in bays with an odd number of joists, but when the number is even, I cannot place them correctly.

I tried changing the justification from center to end and start, but I still cannot get the joists in the right place. I know what my spacing is so I've been using "Fixed Distance" (5'-11" in my case). To get the result I want, I have to create a pretty ridiculous beam system where I specify a fixed number of joists (8 in my case) and then modify the sketch to be much larger until I get the desired spacing of 5'-11". This just doesn't seem right.

EDIT: See attached file.

[ford347]

Hey,

hopefully this helps. I explained it in the file. Let me know what you think.

Josh

[dbaldacchino]

Hmmm, how did you make it part of the beam system?

[ford347]

The last beam?

[dbaldacchino]

Oh, I just noticed....your added joist is not part of the beam system. This works but it's still not what I want. I think there's something wrong with how B.Sys. work as it shouldn't be tied to an odd number of members. I'm going to try in RS4 to see if the same behavior occurs.

Thanks for your post BTW :)

EDIT: It's doing the same in Revit Structure 4. This behaior is really weird. If you enlarge the sketch and justify it as End or Beginning, if there's not enough space to fit an odd number of joists, it'll move the start/end joist far from the edge. I think this is going to support.

[Adam Mac]

I think the beam systems should include the first and last beams, with an option to show them or not. But basically, if you pick the start and end point of your "system", then that means there should be beams at those locations.
It kind of defeats the purpose having to add an extra 1 beam along one side or other?

My 2c worth.....

[ford347]

Ditto!! This one drives me nuts. It's a beam system, so whats the point of having a beam system with a missing component. Basically, they should have the options, center, beginning, end, beginning/end. or like you said, give you the option. And, have you ever noticed that if you are experimenting with how you want your beam system to look, and you don't like the outcome after finishing the sketch, you actually have to undo your movements to change the beam system, rather than just opening up the properties of the beam system and changing it, expecting the changes to take place?? But they don't. This one bugs me too. Anyway, not to hi-jack the thread, but I feel the pain in the forum on this one!

Josh

BTW o dbaldaccino, did you give it a shot in RS, how did it work out. Diff then in RB?

[dbaldacchino]

I just filed a looong and extensive SR on this and other related problems not mentioned in this thread. What it boils down to is the fact that Revit assumes that you want a beam in the center of the span when you select the Centered justification. That doesn't always yield the most economical solution as it adds an extra beam in 50% of the cases where you don't actually need it. So Revit needs to be smart enough to recognize that and choose the best layout or give us a checkbox for "Beam at center of span" which results in conrolling whether you have an odd number or an even number of members.

On another tone.....have you tried using beam systems in Revit Structure 4? When in a framing plan you can create an entire beam system by just clicking in a bay as it will find the extents, kinda similar to the way the ceiling tool works. But in Revit Building...no such luck. We're forced to use sketch mode. I don't like to see such features subtracted from RB, as beam systems work exactly the same and I see no reason for taking a good productive method out. Enough now...happy Thanksgiving all!

EDIT: Yep, same behavior except what described above. Esentially a beam system "fills in" between the extents, so now I understand the concept of justification to End or Beginning when using Fixed spacing. If you set 5'-0" as your Fixed Spacing and Start justification, it'll leave 5'-0" and only then will it start placing beams. Thanks to one of our bright engineers for poining that out....way to go Greg!