Direct Analysis Method
Direct Analysis Method
(OP)
I have been trying to replicate the results of a Direct Analysis Method example given in an article in "Structural Engineer". The analysis is of a fixed-free column subjected to an axial and lateral load at the free end. However, I have tried many different approaches and can not seem to match the values they get.
I know that many computer programs are now capable of doing second order analysis and even the Direct Analysis Method, but I would really like to understand how to obtain the answer by hand.
I have attached a file containing the article with the example, as well as my work. Does anyone know where I am going wrong?
I know that many computer programs are now capable of doing second order analysis and even the Direct Analysis Method, but I would really like to understand how to obtain the answer by hand.
I have attached a file containing the article with the example, as well as my work. Does anyone know where I am going wrong?






RE: Direct Analysis Method
If you look at page 16.1-198 of the 13th edition manual, you will see that for alphaPr/Py<=0.5 taub=1.
In your case alphaPr/Py = 0.43 so taub=1.
You used the equation when you shouldn't have.
RE: Direct Analysis Method
RE: Direct Analysis Method
Anyway, using 0.001 and taub=1.0, I get a Mu = 1772K-in. This is not exactly what they get in 1753K-in, but it's pretty close. Do you have the rest of the article? I would be interested in seeing it.
Check out the article I posted in this thread. You would probably be interested in reading it. It's directly from AISC
thread507-221470: "Do not use K-factors if you're running a p-delta/p-sigma analysis"
RE: Direct Analysis Method
And I actually found that article you posted yesterday, which was extremely helpful. I had been looking everywhere for an actual numerical example on the application of the Direct Analysis Method. It seems like DAM theory is everywhere, but what good is that if you don't know how to apply it?
I attached the full article that I was referencing. It is a little outdated, but still useful.
RE: Direct Analysis Method
Thanks for the article.