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Interpreting IFST Results for Reinforcement

Interpreting IFST Results for Reinforcement

Interpreting IFST Results for Reinforcement

(OP)
Hi all, apologies if this is rudimentary but I am getting myself confused with using the internal force summation tool (IFST) in RISA3D and interpreting results. See attached example. Slab is supported at the edges as shown in the attached. Mx is in the long direction; My is in the short direction. I need to reinforce both directions as there will be moments in long direction and short direction in between supports as well as towards the middle of the slab. I don't know what "strip" I should take and what the IFST is telling me. For example in Photo 3 of the attached, the entire model is selected and my M1 value is ~123k-ft corresponding to the A-B cut line as shown in the photo. I am assuming that it is Mx based on it being in the long direction. Is that 123k-ft across the entire model? Do I divide it by 27' (the length of the slab) to get the average moment per foot on the long direction? Or how would you suggest cutting it to obtain moment per foot in the long direction and short directions? Just general guidance on how to interpret the results would be helpful. I've read through the RISA3D blogs and manual and I'm still not fully understanding how to interpret the results.

RE: Interpreting IFST Results for Reinforcement

RDR89, I usually goto the plate forces tab and get my max forces from there via an excel spreadsheet. The spreadsheet gives you moment values for each individual plate. Pretty easy to sort out with a pivot table and excel makes these very easy to create.

The values are in /ft, so if your plate size is anything except 12" x 12", you will need to scale the moments. Don't forget to add your Mxy to your max moment.

This is not your exact question, but I try and avoid the black box that is typical with making strips in RISA, which is what you're running into.

RE: Interpreting IFST Results for Reinforcement

(OP)
WesternJeb you’re right. I’ve used the plate forces before with excel just as you’re describing. I had a larger slab this time and wanted to see if I could get some insight to the IFST

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