## 5 Conclusions  
The friction-yielding damper CAR1 has been used to improve the seismic behavior of an existing two-story RC structure located in Greece, constructed in 1979 and no longer meets the requirements of current anti-seismic regulations. In this paper, two alternative solutions with the use of CAR1 positioned in the steel diagonal braces are presented and compared. A nonlinear static pushover analysis in both directions is performed following the ATC 40 procedures [19] to assess the performance of the framed building under different levels of shaking (\"Life Safety\" and \"Collapse\"). For the first redesign of the building RD1, we selected steel diagonal braces with an X shape in only one frame in each direction and on each side of the building for the two stories, and for the second redesign RD2, we selected steel diagonal braces with an X shape in two frames in each direction and on each side for both stories. The properties of each damper CAR1 have been selected based on previous experimental and numerical results [21; 31] to protect the steel diagonal braces from buckling.  
Based on the findings of this paper new conclusions are drawn.  
i. The effectiveness of the friction-yielding damper CAR1 has been successfully investigated for an existing low-rise (2-story) RC building that no longer meets the requirements of current anti-seismic regulations. The seismic base shear load of the BM0 building is \(\Sigma\)F = 20236 kN, but the appropriate/needed seismic base shear as \(\Sigma\)F\({}_{\text{needed}}\) = 4007.20 kN is calculated in each direction to achieve the criteria of EC8 [23]. It is noticed that RD1 can take 149.2% (6080 kN) and 135.6% (5960 kN) larger base shear loads in the x-x and y-y directions, respectively, and RD2 can take 212.3% (7620 kN) and 198.8% (7560 kN) larger base shear loads in the x and y directions, respectively, for the same level of displacement (drift = 2%) compared with the appropriate/needed seismic base shear.  
ii. The damper CAR1 can be used in existing buildings that no longer meet the requirements of current anti-seismic codes, minimizing the plastic hinges of the columns, and protecting the steel diagonal braces from buckling. This study highlights the easily process to select the appropriate characteristics of the dampers from a wide variety of choices [20; 21; 31]. Also, the strengthening level can be easily adjusted or modified during the years based to the appropriate selection or modification of the number, the dimensions, and the elastoplastic properties of the blades.  
iii. The plastic hinges of the columns of BM0 remain in the Life Safety (LS) performance level, so the building has not suffered substantial damage as a result of the horizontal displacement of 18.4 cm at the top of the building. In the y-y direction, the columns of the ground floor have not suffered substantial damage (IO), but the columns of the first floor are in the yellow zone (collapse C), which means that severe failures have occurred. The hinges of the columns remain in the Life Safety (LS) performance level in both redesign buildings (RD1 and RD2) and in both directions so the buildings have not suffered significant damage as a result of the horizontal displacement of 18.4 cm at the top of the building due to the use of the dampers CAR1. In addition, with the installation of the dampers CAR1, the buckling of the steel diagonal braces has been prevented.  
For medium-rise and high-rise buildings (existing that no longer meet the requirements of current anti-seismic regulations), the use of the dampers CAR1 needs to further investigate additionally with other techniques like FRP that would improve the column original design strength for possible axial, shear, or flexure and in some cases allow the structure to carry more load than it was designed for.  
This research received no external funding.  
Not applicable.  
To ex-assistant [PERSON] from Aristotle University of Thessaloniki, Greece.  
The authors declare no conflict of interest.