Seismic response of multiply connected MDOF primary and MDOF secondary systems

New algorithms are presented to evaluate the mode shapes and frequencies of a coupled system, given the mode shapes and frequencies of the uncoupled primary and secondary systems. These coupled mode shapes can be used to obtain the dynamic response of the total system given the input to the primary system. This information can also be used to develop instructure response spectra (IRS) at the connecting DOF, along with the correlation between the motions at the connecting DOF.