The basic purpose of reanalysis methods is to compute modified solutio
ns without a complete structural analysis for each design modification
introduced. Only the knowledge of the solution of the initial problem
and the definition of the modifications are required. The resulting s
aving of computational times allows the designer to do repetitive anal
yses of large finite element structures. This paper presents, in detai
l, two efficient techniques for computing the modified forced sinusoid
al response of structures. These two methods both take into account ma
ss, damping and stiffness modifications. In view of the numerical resu
lts obtained, concerning a 36 dof simple clamped plate model, the usef
ulness of these methods has been proved.