Hat tip to WillisV for his comment on user documentation. After reading his post, I asked my boss to upgrade us a couple of weeks ago. If you don't have SAP V11.0.7 or later, the user documentation for 2005 AISC was not included >:-<. But now that they've finally come out with documentation on 2005 AISC, the implementation is more thorough than I had expected. SAP appears to tackle all the major DA requirements discussed here: automatic reduction factors for section EI and EA per code to account for residual stresses, notional loads, and P-Delta including ? effects. Because of the requirements of P-delta in both DA and equivalent length methods, the 2005 code seems be pushing certain specific analysis methods. This is a bit of an oversimplification, but with the DA method, you basically have a tradeoff, you get to use K=1 instead of working with alignment charts and the adjustments to them, but you have to take a (typically) 20% reduction to section EI in exchange.
Notional loads (for out-of-plumbness effects) have to be defined for each gravity case, a minor pain, but then SAP automatically generates the lateral loads based on user specified percentage of each gravity load, typically .002 or .003, and it will automatically create load combos using these notional loads. If you don't have SAP, you'd calculate each gravity load at each level, not counting loads from above, then generate your notional lateral loads in each direction from there.
SAP automates one other important function that I think other methods may struggle with: the combination of factored loads using nonlinear P-delta analysis combos which are automatically used for design. Since P-Delta is a nonlinear analysis, you cannot run individual nonlinear load cases and then later combine them with other loads using linear sum for design. In earlier versions of SAP, you could have used 'Analysis cases' to define these nonlinear factored P-Delta combos, but now, all you do is either define linear factored load combos yourself or let the program create the combos automatically, then press a button to convert those factored load combos into nonlinear P-Delta used in analysis and design. That is a really nice new feature.
WillisV made a statement upthread about the need to add up to 4 intermediate joints along the columns to properly handle local P-delta effects. Had I not spoken to a CSI support engineer about this very topic, my instinct would have been to agree with him. However, according to this CSI engineer, and he was adamant about this, you would typically not need to add any additional intermediate joints on the columns at all to properly account for local P-?, but in some cases you might need to add 1 additional joint through the frame auto-mesh so as not to alter unbraced lengths. He insisted that due to some uniqueness in SAP's frame element formulation, you would NEVER need to add more than 1 intermediate joint to properly account for ?. I've been doing a little experimentation on this, and the support engineer so far seems to have a point.. at least in the examples that I've run through. In SAP, to add the intermediate joint you would select all and then Assign a frame automesh and divide the selected element into 2 segments internally. That way, the frames are divided internally, but reported and designed using their true lengths.
CSI has made some good strides over the past few years in my opinion regarding user friendliness. The office I work in now has SAP and Risa, but I worked with RAM a few years back and my opinion is that RAM was not that much more user friendly. They had good modeling tools and and load distribution options, but they had problems too.. for example, you used to have to redraw members each time in RAM in order to move them because RAM didn't have a command to let you move them... and I recall that sloped beams didn't work at that time. Back then RAM was faster off the mark in adding the ASCE wind loads and incorporating them in the load combos, a very important advantage at the time, but CSI seems to have largely caught up with them in the auto lateral load area, and trumped them with auto-wind loads on open frame structures and nice implementation of IBC 2006 quake. And I haven't seen any program that comes anywhere close to what SAP now offers for automating the 2005 AISC, with the auto-reduction factors, notional loads, etc., and with the specific code requirement regarding P-? which most other programs don't address along with the reduction factors to EA and EI for the DA method, it seems that the other programs have a long road ahead of them to catch up with what SAP offers now. I just don't see that wide of a gap between the programs on user friendliness as WillisV suggested, but your mileage may vary.
