I superimpose two of the load cases into one result combination by using the 'Or' criterion. The results graphic of the result combination, however, shows deformations smaller than the two contained load cases.
Furthermore, I get a positive as well as a negative maximum value for the RC, despite the fact that the individual load cases yield positive deformation values.
In the result combination, RSTAB superimposes the (orthogonal) components u-x, u-y und u-z of the individual load cases and creates the total deformation u. According to the definition of the coordinate system, the orthogonal components of the load cases can be positive or negative. Therefore, it is only a display issue, because the deformations u shown in the graphic are not definitively specified in terms of their direction.
The determination of the RC extreme values yields two values: maximum and minimum. The geometric addition of the minimum and maximum value yields the correct deformation value of the result combination. The results table shows he correct value.