Reduction of Dynamic Matrices using Static Condensation

If we are not interested in tracing all degrees of freedom for each time step, we can always perform analysis on the reduced dynamic system

Dynamic analyses are much more expensive than static analyses. In case we are not interested in tracing all degrees of freedom for each time step, we can always perform analysis on the reduced dynamic system or so-called subproblem and then obtain the response of the original system by back substitution or transformation. It should be noted that the result obtained from subproblem might have some characteristics: