I am having trouble telling RAM where to put a secondary layer of longitudinal reinforcement. If I assign a different value to 2 Layers in the Beam Criteria it appears to assign my values under 2 Layers just to my top bars. I have attached a screen cap of my Beam Criteria and a sheet from my Beam Design Summary to illustrate the issue. I am afraid I might have a fundamental misunderstanding that I can't find a clear answer for in the manual.
Thank you.PDFPDF
I will give that a try when I have time to get back into it. As it is I had a multi-span beam line with bars running full length spliced with the bars in the next beam line.
Thank you.
It gets complicated if some bars in one layer are longer than other layers, or if the bars straddle from span to span with different depth beams. You can confirm if that's a factor by hooking the bars in the column as a test. Otherwise send us your file via Secure File Upload
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Thank you for your response.
So that makes sense that it's just the dt for the two layers and I assume that the 2 layers are then separated by the code minimum. This was not something I inferred from reading the Concrete Beam FAQ before or after your response.
But then why would the program apply the 2 layer criteria to my top bars, but only the 1 layer criteria for my bottom bars? Does RAM look at the beam's deflection and override the 2 Layer criteria for bars located in the tension face?
In the criteria, the user is indicating where the center of the bar group created from the two layers is estimated (not the absolute location of the 2nd layer). We do this to simplify the design because we can assume the two layers are acting at a particular 'd' value and check capacity without iteration. Then we do a final check to make sure the 'd' value used in the capacity check is not more than the maximum d value that would fit.
This is noted on our Concrete beam FAQ in the section on Effective Depth.
Answer Verified By: Max Karr