EFFECTIVENESS OF INSERTING DAMPERS BETWEEN FRAMES AND LATERAL RESISTING ELEMENTS FOR THE MITIGATION OF THE SEISMIC EFFECTS

This paper presents the results of an extensive (analytical and numerical) study carried out to investigate the effectiveness, for the mitigation of the seismic effects, of placing viscous dampers so that they connect frame structures and lateral resisting elements (external or internal to the structure). A first analytical approach carried out with reference to a basic system composed of two adjacent SDOF systems linked by a single damper is developed in order to understand the physical properties which govern the problem in question. Then, a wide series of numerical simulations is carried out with reference to seismic inputs. The results show that this peculiar damper placement is capable of providing damping effects (in terms of reduction of the structural response) which are much larger than those which could be provided by typical interstorey damper placements in the frame structure. This innovative arrangement substantially differs from the usual interstorey damper placement and leads to a clear indication for a new and efficient conceptual design for structures to be built in seismic areas. This peculiar damper arrangement for inserting added viscous dampers in shear-type structures, if damper sizing is chosen appropriately, may be traced back to the indirect implementation of the so-called MPD (mass proportional damping) system which has been extensively studied in previous research works by the authors and has proved to be characterised by superior dissipative properties.