Finite element analyses on free from damage seismic resisting beam-to-column joints

The seismic design strategy implemented in current codes is based on the capacity design principles that allow the formation of plastic hinges into predefined parts of the structure. Therefore, significant damage is expected at ultimate limit state, to which high repair costs are associated. Recently, new design strategies have been proposed in order to avoid the damage of the structure. The most of them are grouped into two categories, namely i) using special damping devices introduced in the structure as additional resisting element; ii) changing the dissipation mechanism of the structure by means of friction-based dissipative joints. The second possibility is promising and really effective because it guarantees no architectural interference if adopted for moment-resisting frames (MRFs), and low forces transferred to the foundations. The novelty of free from damage (FREEDAM) joints lays in the fact that the energy is dissipated by friction at the interface between plates in contact instead of the classical plastic deformation energy dissipation mechanism. In this paper, the seismic behaviour of FREEDAM joints is investigated by means of parametric finite element analyses carried out in order to examine the influence of geometric and mechanical feature of the friction device (e.g. position of friction plane, type of friction interface, bolt clamping, bolt strength). The accuracy of finite element models is also validated on the basis of some experimental tests.