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Status Future consideration
Created by Guest
Created on Apr 25, 2024

Allow Pseudo-Diaphragm Loads to be applied to beam-only frame lines

Currently RAM Frame only applies pseudo-diaphragm loads to beam/column frame lines that include columns and the loads are subdivided based on the column tributary areas, not the beams. However, in many cases, collectors need to be detailed for various building applications that may not have a lateral column element supporting the beam.


In these cases, RAM Frame will not correctly apply the axial load to the beam line unless the column is assigned to the frame line and is a lateral member (but in those cases, the user then must manually change the beam/column fixities to ensure moment is not transferred).


Where this becomes problematic is if a collector does not fall on a column line. For example, in the case where a building has a 2nd floor that cantilevers off the side of the building. The edge members would still be the preference to assign as collectors, however the psuedo-diaphragm loads will not be applied to the collector line because there are no column elements below. In these cases, the only option for the user is to change the diaphragm to semi-rigid.


Instead of the program applying pseudo-diaphragm loads based on the column properties, the loads should be applied based on the beam properties. That way, a user can apply a psuedo-diaphragm load to a beam-only lateral line and still get the corresponding axial design forces.


Also, why has copy-pasting not been implemented into the psuedo-diaphragm frame distribution percentages input yet? It is extremely annoying to have to type in 30+ frame lines by hand when the calculation has been performed in excel and is already in tabular format and could easily just be pasted. Even more annoying when all the distribution percentages get reset because a frame line changes and everything has to be re-entered again.



  • Admin
    Seth Guthrie
    Reply
    |
    May 8, 2024

    Backlog item 565260 previously logged for copy and paste.

  • Admin
    Seth Guthrie
    Reply
    |
    May 8, 2024

    It is presumed that every lateral beam would be supported by a lateral column. Not doing so leads to an unstable structure since gravity members are not in the stiffness matrix.

    The proper design of collector beams has been a challenge for a while. I'll pursue some possible options.

    Meanwhile the copy and paste issue looks like a defect. Copy works, but there is no paste. Adding to backlog.