03.09: Performance assessment and design methodology of free from damage moment resisting frames

Abstract

ABSTRACTThe seismic design strategy implemented in current codes is based on the capacity design principle that allows 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 really promising and effective because it guarantees low forces transferred to the foundations and no architectural interference, if adopted for moment‐resisting frames (MRFs).The novelty of free from damage 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.The performance of MRFs equipped with free from damage joints differs from that of conventional MRFs. This implies the need to update the current EC8 rules to free from damage MRFs. Therefore, in this paper new design criteria have been proposed. The effectiveness of the new rules has been verified by means of a comprehensive set of numerical analyses, by comparing the seismic performance of two sets of frames having geometrical configurations that are typical for current European practice: a set of traditional MRF structures (EC8 compliant) and another set of MRFs equipped with friction joints.