I am currently designing a building using Ram Structural System with ASD load combinations for the steel design and LRFD for the concrete footing design. I have a few pairs of steel columns that are very close to each other and each pair will share a common footing. Should I use a RSS continuous strip footing to design a footing for each pair of columns? And if I do this, what kind of design will I get?
Or should I try an ISM import into Ram Elements to get the column loads and use the Combined Footing module? Will all of the column loads be imported if I run through a gravity load analysis in Ram Steel Column or Ram Foundation? If I have Lateral Frame Columns, will Frame analysis loads be imported?
Or should I bypass ISM and import the model directly into Ram Elements? Will all of the column loads be imported if I run through a gravity load analysis in Ram Steel Column or Ram Foundation? If I have Lateral Frame Columns, will Frame analysis loads be imported?
Would I be better off by taking the column loads manually from the RSS Steel Column analysis and inputting these directly to the Ram Elements Footing stand-alone module? For the lateral columns, I would have to find these load case reactions (somewhere???) and do the same thing.
Or do you have a better suggestion? I would like a simple workflow for these options.
Will the imported column loads come across as ASD load case reactions or as load combination reactions?
If the columns are centered on the footing and all the forces are in-plane, then a continuous footing design in RAM Foundation is fine for those column pairs. There are further details about the analysis and design of continuous footings in the program manual, but in a nutshell, we treat it like a 1-dimensional beam on periodic compression-only springs. This also works for more than 2 columns in a line.
The combined footing module in Ram Elements is limited to column pairs, but does a nice job. You can design a footing with the columns in the middle or shifted to any edge or corner so it's a little more versatile. Taking the whole model to Ram Elements and rerunning the analysis just for combined footing design might be extra work. Using the combined footing module in Ram Elements as a Stand-Alone module with column reactions manually input is probably just as fast.
The other option, and one that works even for groups of columns that are not in a line, is to design the foundation as a mat using Ram Concept.
See also:
Answer Verified By: SVGregory
A 1-dimensional footing would only get the reinforcing in one direction. It sounds like the Ram Elements module is the way to go. What are the best reports in Ram SS to get the column reactions from the gravity and lateral load analyses?
We still design transverse reinforcing for continuous footings (or stirrups depending on the cross section aspect ratio), but this is based on uniform pressure across the width. We don't design for rollover forces.
You can export out the Ram Frame reactions now to make filtering or sorting easy. Otherwise the load case reactions are best IMO.
See also: https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/32981/appendix-b-ram-structural-system-data-available-through-sqlite-technology-preview
Thanks! i will probably still model the paired columns on a continuous ftg in Ram SS to give me a quick look at the footings and to remind me which column reactions I need to pair up in Ram Elements.
I might try the SQLite database inquiry if it doesn't get too difficult. I have had a hard time in the past trying to find the right native report in RSS to get some results such as column reactions separated into load cases.