Abstract
Secondary structures mounted on primary structures such as water tanks and towers on buildings are exposed to the amplified floor motion under earthquakes. The elastic responses of them have been almost made clear and various propositions on design spectra have been made on the elastic design basis. The inelastic responses of them, however, have been scarcely investigated and the ultimate resistance of those structures to earthquakes is still left uncertain. This paper aims to clarify a general feature of their inelastic behaviors. As for the inelastic behavior of the primary structure, the total energy input exerted by earthquakes may provide a sound measure for the structural damage. On the same context, emphasis is laid on the energy input of the secondary structure and the correspondence between the elastic response and the inelastic response is made clear in the light of the energy input. It is concluded that the inelastic response spectra for secondary structures can be readily depicted on the basis of the elastic response spectra of them.
