huangyhg

aci interaction diagrams
can anyone recommend a method or updated tables that reflect the new phi factors (.65 ties, .70 spiral) in the universal column interaction tables in the aci design handbook. the most recent tables i have been able to find are from the 1995 handbook, which uses the old phi factors for compression (.7 ties, .75 spiral). i have been modifying the tables by multiplying times the change in phi factor (typically 1.08 for a .65/.70 difference), but i have found nothing to back me up from aci. any thoughts?
your approach sounds perfectly reasonable. that being said, do you have a program like pca column? if not, you can generate your own interaction diagrams. it might take an hour or so to set one up, but once it's done you can copy it and modify it for any case (b, h, rho, f'c, etc..) that you want. it can approach the nice, smooth curve from the charts because it's a spreadsheet so make a ton of points - you don't have to stop at 4 points as though you were doing it by hand.
pca col or s-conc are god sends.
csiberkeley has a new product out called "section builder" which generates many user friendly curves like pmm, m-φ etc. i have not yet tried it out completely, but seems promising.

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