This page contains frequently asked questions related to generalized displacements.

On this page:

Can I use generalized displacements to estimate joint rotations in a model that consists of solid elements only?

Yes, suppose the position vector from joint 1 to 2 is given by (dx,dy,dz). Then you can define a generalized displacement of type rotation for the rotation about the Z axis as Rz = dx*dUy – dy*dUx. Thus the coefficients to define the generalized displacement are for Joint 1: (dy, -dx, 0, 0, 0, 0), and for Joint 2: (-dy, dx, 0, 0, 0, 0).

Separate rotational generalized displacements can be defined for Rx and Ry, if needed. Once defined, these can be plotted and output in tables.

Can I use generalized displacements to calculate strains?

Yes, you can use generalized displacements (defined via Define > Generalized Displacements) to calculate the strains from joint displacements for elements for which the strains are not directly reported by SAP2000.