I'm trying to understand the different scenarios in Staad for beam bracing.
Non-Physical Member (not sure what to call this)
I understand by default the program considers the length of member (node to node) as the unbraces length. So for a girder or beam which is segmented between joists/beams, this would be the unbraced length for the top and bottom flange. To change this value, you would need to change it in the design parameters. For example, if designing with AISC you can set the unbraced length UNB, UNT, etc.
Physical Member
How does the program handle infill beams framing into a girder? Does it brace both flanges similar to RAM? Is there a way to specify brace points? Maybe there is a video or example that better explains how the physical members are treated?
Thanks!
For Analytical members, using the UNT and UNB is the only way to handle the unbraced lengths. For a situation when the braces are not modeled, although you can specify the unbraced length using these design parameters but there is no way to specify the location of the brace points, at least when it comes to the AISC code.
Physical Members defined in the Analytical Modeler serve as "groups" for analytical members using which you can do some preprocessing and postprocessing on those members but the physical member information does not carry over to the design phase. So when it comes to design as per AISC codes, you would still need to specify the design parameters UNT and UNB appropriately.
The Physical Modeling mode in STAAD.Pro is being developed so that it can handle the design related boundary conditions based on the physical member as opposed to the analytical member but that is in the pipeline and not available yet.
Answer Verified By: RFreund