In performing an integrity check in RAM Modeler, this warning appears:
The High Roof level consists of columns, a 1-way 6" slab, and beams.
The Level below consists of beams, columns, and a 2-way 12" slab supporting the High Roof columns:
The warning occurs for High Roof columns 1, 2, 3, 5, 7, 9 ,11, 13, 15, 17, 19, and 20. These columns had their fixities defined as such:
The fixities highlighted in yellow represent the columns that land on beams, pinned at the base and fixed at the top. The white fixities shown are 2-storied cases (High Roof and Roof levels) attempting to utilize the continuous columns for lateral resistance for the High Roof but not as a lateral resisting system for the building as a whole.
Questions:
The beams shown in the images above are designated as Lateral, but have their fixities modified to be pinned at each end. Given the wording of the Warning, it appears the program interprets these releases as making the Lateral member "Gravity" when running the Integrity check. Does this warning have any merit for the given situation?The fixities of these columns were required for lateral analysis to limit instabilities at nodes on the High Roof. Do these fixities capture the proper intent or is there a better modelling practice to capture this? At the base of all the columns going to the foundation, there are 4' tall 24"x24" plinths, these connect the columns to the spread footings. To solve an instability issue their fixities were maintained as fixed-fixed, with all other columns (Lateral) set to pinned-pinned. Does this also merit revision?
If you have a beam below and supporting a lateral column above, that beam should be lateral. Gravity beams won't be considered in the analysis at all (that's different than being pinned).
If you also have a 2-way slab, then the slab can support the column theoretically, but surely if the beam is there in the model it ought to be considered in the analysis and thus lateral.
Pinning the lateral columns should be fine, though if you pin the top of a column and also pin a lateral beam at the top you are likely to get an instability.
Answer Verified By: Eric Feuge-Miller
Based on the layout though, the lateral columns (Top fixed and bottom pinned) frame into lateral beams (pinned-pinned) which frame into lateral columns below (pinned-pinned) and the warning still pops up.
Without the model it's difficult for me to confirm, but run it in Ram Frame, check the node numbering, foundation nodes and the deflected shape. If that all looks good then you can ignore it.
After making some alterations it appears that this warning will pop up even if all related framing members are designated as Lateral and if they are all fixed-fixed. It could be the fact that a two-way slab, combined with lateral columns over transfer beams, will result in the program assuming the column is bearing on the slab:
I too am having this warning pop up. Lateral column sitting on lateral beam, but with 2 way slab produces the warning. Warnings can be ignored, but is there any analytical or design penalty? I've uploaded my model through the secure file upload.