Questions

I am performing a basic static analysis. In the saclst file, there are results about OPTIMIZATION DATA and J O I N T  D A T A  L I S T, 

1. What does the data in the 'OPTIONATION DATA' table mean, and how to use it?   

   

2. What do the last three columns of the "* * * J O I N T D A  T A L I S T * *" table represent, how to understand them, and how to make adjustments in the model file?

Answers

Below is how to read and use those two sections in your saclst output:

1. OPTIMIZATION DATA

    

Information in this section tells you how well everything is arranged for solving the stiffness matrix.

• Optimized Final Bandwidth - is the half-bandwidth of your global stiffness matrix after SACS's automatic renumbering of joints.
• Final Maximum Bandwidth - is the worst-case half-bandwidth (the single largest spread of coupled DOFs on any matrix row).

A lower bandwidth means the solver stores less data and runs faster calculations. If your numbers are still high, you can speed things up by manually grouping related joints in your input (or using the Joint > Reorder option in Precede) so SACS can pack them tighter.

2. The last three columns in the  *** JOINT DATA LIST ***

    

• Optimized Joint Order - where SACS has placed that joint in its internal solve sequence (1, 2, 3, ...)
• Joint No. - where the original joint IDs occupy that solve-position
• Begin Row Loc. - The row index in the stiffness matrix where this joint's first degree-of-freedom lives; the next five DOFs follow in the next rows

How you can use this data: 
Read the mapping to see exactly how SACS renumbered the joints. You can improve it by either renumbering your joint entries in the sacinp. so that highly connected joints (those that share a lot of members ie. beams, braces, plates, etc, between them) are listed consecutively (for example 100, 101, 102,..) rather than scattering them (100, 445, 300, 11, ...) or use Joint > Reorder in Precede to prescribe a custom order.

     

When two joints are mechanically linked (through many members), their stiffness terms end up next to each other in the global stiffness matrix. If their joint IDs are numerically close, the non-zero entries stay near the diagonal, which will reduce bandwidth and speed up the solver and lower memory use.

Here's how to tell whether you need to reorder:

1. Look at your printed bandwidth numbers and compare them to the problem size.

In your saclst output, the Final Maximum Bandwidth is 4. A model with 8 joints (6 x 8 = 48 DOFs) is tiny. Even if you renumbered manually, you'd struggle to drive that number below 4.

2. Solver speed and memory

For a handful of joints, the solve takes milliseconds and uses virtually no memory, regardless of bandwidth. You only need to think about reordering the joints when you have hundreds or thousands of nodes, and the printed bandwidth runs into the hundreds or thousands.

So, for your case, since your "Final Maximum Bandwidth" is already very low (and your structure is small), you do not need to reorder the joints. The solver will run just as fast as it can, and you won't see any meaningful improvement by renumbering such a simple model.