SAP for AISC Direct Analysis Method?
SAP for AISC Direct Analysis Method?
(OP)
Has anyone used SAP for direct analysis? If so, I'd appreciate it if you would share your knowledge and experience. I couldn't find any SAP documentation on direct analysis, but in version 11.02, it shows up in the steel design menu option when you change to AISC 360-05.
From a seminar I attended several months back, direct analysis method looks interesting, as it allows you do away with equivalent length K factors if certain criteria are met. If you google AISC Direct Analysis, you should find a good (free) Aisc paper by Shankar Nair on stability analysis. We just need to figure out what SAP is doing with direct analysis.
From a seminar I attended several months back, direct analysis method looks interesting, as it allows you do away with equivalent length K factors if certain criteria are met. If you google AISC Direct Analysis, you should find a good (free) Aisc paper by Shankar Nair on stability analysis. We just need to figure out what SAP is doing with direct analysis.





RE: SAP for AISC Direct Analysis Method?
I did some grad work using SAP2000 with this method and comparing it to the true direct method (ASCE notional load method), but I haven't tried this new code in SAP2000. I'm wondering how it will iterate the EA and EI stiffness modifications. Of course its no surprise there is no documentation for this in SAP2000. You can't find anything valuable on their nonlinear links either, just a bunch of theoretical stuff with no advice on how to apply it.
If I appear PO'd about the state of code writing I am. I think its really getting out of hand. The IBC wind provisions are another example of committee hijacking. These people don't have to use their handywork, they just want their name in a piece of the code. What a joke.
RE: SAP for AISC Direct Analysis Method?
Look, if you're going to criticize Nair and/or other code committee members, fair enough, this is a free and open forum. But please make your case from an educated, practical engineering standpoint, and back your viewpoint. Otherwise expect to get pushback from those of us who don't respect unsupported knee jerk assertions. I'm here to try and absorb viewpoints of others. But you seem to be making broadbrush claims without supporting your viewpoints. If I've mischaracterized your opinions, then please make your case as to why the Direct analysis method is so bad.
RE: SAP for AISC Direct Analysis Method?
As for ELM vs DAM, the DAM might be more complicated than it needs to be, but the ELM is a travesty beyond description. I'd venture to say that 95% of all structural engineers apply teh ELM WRONG because they just apply the alignment charts without adjustment. All these adjustments are unbelievably difficult to apply correctly, even for engineers who are very interested in and experienced with steel design. The DAM is a brute force, bulldozer method and is very easy to understand. Assuming that CSi implemented it correctly, it should be much easier to apply correctly than the ELM.
RE: SAP for AISC Direct Analysis Method?
Based on my reading of Appendix 7 and the AISC seminar I attended several months back, CSI appears to have a real winner on their hands with their implementation of the DA method. They have done a really good job in the automation of it. Automatic reduction factors to section EI and EA depending on your choice of TAUb fixed or variable, they've automated the generation of notional loads, automatic handling of local P-delta analysis as well as sway per code requirements, and they also automate the creation of analysis cases used in P-delta. CSI appears to be paying closer attention to details.