## 6 Conclusions  
This paper investigates the efficacy of friction-damper devices at beam-to-column connections in RC frames in seismic areas, in the presence of self-centering systems at the column-base connections to the foundations.  
The results of FE analyses conducted as feasibility studies are presented. Three different BCCs are proposed: with crossed slotted holes (BCC-1), with curved slotted holes (BCC-2), and curved slotted holes with Perfobond connectors (BCC-3). These solutions also differ for the device adopted as center of rotation: in the first solution, there is a pin  
Figure 11: Moment-rotation curves of IF-TB vs. IF-FD: (**a**) column base-section; and (**b**) CBCs.  
Figure 10: Moment-rotation curves of IF vs. TF: (**a**) beam end section; (**b**) column base section; (**c**) panel zone; and (**d**) friction device BCC-2.  
while in the other two proposals, there is a T-stub with a weakened cross section. The two last solutions showed to be the most performing in terms of accuracy of the center of rotation position, stability of the hysteretic cycles, and amount of dissipated energy. As a preliminary analysis, BCC-2 is considered as the type of connection introduced in a two-storey and two-span MRF. The latter is studied by means of push-over analyses and NLTHAs considering different configurations: first of all, a traditional frame without friction dampers is modeled (TF), then, an innovative frame endowed with BCC-2 at joints is analysed (IF), and, finally, two frames equipped with self-centering devices are considered, i.e., with threaded bars used in combination with disk springs (IF-TB) and with added friction pads on the column splice (IF-FD). The capacity curves obtained from the push-over analyses showed that the introduction of friction dampers is effective in preventing the MRF from the damage of the RC primary structural elements for values of the drift up to the achievement of the ultimate capacity in rotation of the systems. The pushover analyses prove that the frames equipped with BCCs exhibit higher initial stiffness due to the lengthened panel zones which make shorter columns and, conversely, a lower value of design strength, which is set for complying with the capacity-design criteria. Moreover, the innovative frame without self-centering systems, exhibits a post-yielding softening branch, which is mainly due to the damaged strength attained in the plastic hinge at the base of the RC pillar. By contrast, the IF-TB and IF-FD exhibited a hardening-type behaviour after the yielding, which was guaranteed by the adequate stiffness of the post-yielding trend of the column-base connection, which allows it to overcome the second-order effects. The results of NTHAs outlined that the frame equipped with friction dampers at both BCCs and CBCs exhibits the most suitable seismic performance. As a matter of fact, the MIDRs and RIDRs are limited if compared to those of the TF and the RC primary bearing structure is prevented from severe damage because both beam end-section and column base-section behave elastically and the friction self-centering device allows the dissipation of a significant volume of energy thanks to its moment-rotation diagram characterized by a flag shape.  
These results demonstrate the feasibility of the design of friction-damper devices in RC MRFs and their efficacy in improving the global and local structural response. As future developments, further analyses are under investigation for the assessment of the seismic response of MRFs endowed with BCC-3 and friction self-centering systems.