I would like to get some clarification on methods that CAESAR II uses to combine elements for load cases.

The Alegebraic method is self explanatory.

However I am confused by the Scalar method. To quote the UG Now as all of these items are vector quantities, how does CAESAR II combine them using the Scalar method? Does it add the magnitudes of the vectors (e.g. a displacement of 1,1,1 with resultant of 1.732, plus a displacement of -1,-1,-1 with resultant of 1.732 would give 3.464)?

Or does it add the magnitudes of the individual components (which would then be the same as a vector addition)?

If we take this further and apply it to a typical situation where we are determining stresses under an occasional load case - see L10 & L11 in the CAESAR II viewlet on load cases - Scalar is recommended as the combination method. In these two load cases the output is only stress. Does this mean that CAESAR II only looks at the stresses from the contributing load cases, and then combines these using the scalar method? In other words, where stress is specified, CAESAR II does not carry out any combination operations on displacements, forces, moments etc.

Ross,

Perhaps we should phrase the text in the User's Guide a little better. The best
explanation of the combination methods can be found in the Help Text for this particular
option. Just click on the Combination Method cell and press [F1]. Here you will find:

Algebraic Combinations:
- Displacemenets and Forces are the algebraic combination of the displacement and force vectors.
- Stresses are not combined, instead they are calculated from the algebraically combined forces and moments.

Scalar Combinations:
- Displacemenets and Forces are the algebraic combination of the displacement and force vectors.
- Stresses are the scalar combination of the stress values (scalars).

The Help Text goes on to state that
Note the numeric example given here also.

You also asked:
CAESAR II always computes all values of displacement, force, and stress. The Output Type setting simply limits what is available for review at the output level. This setting can be used to minimize the amount of data inexperienced users may misinterpret (such as stresses from an OPE case or displacements/forces from an OCC combination case).