# Reduced Stiffness & P Delta
The element stiffness can be partitioned into structure (
Giving the reduced equation
When creating the structure stiffness matrix the element matrix can be assembled and then reduced as above before being included in the structure equations.
Once the structure displacements are calculated the element displacements can be established from
And the element forces as
For a P-delta analysis the global solution is modified to
but the element force calculation is unchanged. This means that once the structure displacements are calculated the element displacements and forces are calculated from