Not a big SAP2000 user but so far as I'm aware, CSI's manuals refer quite frequently to Ed Wilson's books and research so that might be a good starting point for understanding some of the software's inner workings (here's a partial online version of one of his books :http://www.edwilson.org/book/book.htm). This, along with the analysis manuals themselves should give you a good idea of how the program needs to be used.

If you're a beginner and want a better idea about the finite element method itself, I'd recommend Daryl Logan's first course in the finite element method. It gives a good idea about the underlying theory and even has a bit of practical information. If you already have some grounding in FEA then Zienkiewicz's first two volumes (Vol 1:Basics, Vol 2: Solid Mechanics) can offer some good insights.

Thanks so much for the link andorrax1 !

Jason McKee
proud R&D Manager of
Cross Section Analysis & Design
Software for the structural design of cross sections
Moment Curvature Analysis
Interaction Diagrams
Reinforcement Design etc.

For basic FEM concepts on Matrix methods, I really like McGuire, Gallagher, and Ziemian's book "Matrix Structural Analysis". Now, it is almost exclusively frame elements. But, it does a really good job introducing shape functions, 2nd order effects and such.

For more complex concepts I tend to look at a few different references. Ed Wilson's book is good for dynamics. KJ Bathe's book is good for plate and shell element formulations. There is also a book by MacNeal that offers a good discussions on various types of elements and where their weaknesses are.

A very classic book is "Finite Element Procedures" by Klaus-Jürgen Bathe. If you prefer something simpler, you could take a look at feaforall.com website.