| Abstract: | This paper attempts to study the response of equipment items attached to torsional buildings supported by elastic bearings under earthquake excitations. To account for the effect of torsion and translation, each storey of the building is modelled with two degrees of freedom, one for translation and the other for torsion. The equipment is assumed to be so light that it affects slightly the vibration modes of the primary structure to which it is attached. Modal synthesis results obtained by the perturbation technique together with the CQC procedure are compared with those from a complete eigenvalue analysis. Using the present semi-analytical approach, the key parameters that govern the equipment and structure responses can be easily identified. In the numerical studies, it is confirmed that the response of the equipment and the building to which it is mounted, can be effectively reduced through installation of the base isolators. The optimal point for mounting the equipment is the one where the equipment remains undisplaced during vibration of the tuned mode. © 1998 John Wiley & Sons, Ltd. |
