On the Relation between Rigorous and Simplified Models for the Dynamic Response Analysis of Multicomponent and Multisupport Excitations

In analysis of structures subjected to multisupport excitations, generally in addition to the support acceleration time histories as inputs, the velocity and displacement time histories are also required. To identify the cases in which it is sufficient to use just the acceleration histories of supports, this paper attempts to show that there is a relation between multieomponent and multisupport excitation analyses. By considering the ordinary equations of motion as a special case of a more general case in which the motions of all degrees of freedom are taken into account, a matrix transformation is introduced, by which the governing equations of the multisupport excitation case are changed into ordinary equations of the dynamic response analysis of multi-degree-of-freedom (MDOF) systems. It has been shown that the “matrix of earthquake influence factors” cannot be defined for all structures in general state of multisupport excitation.