## 6 Application of the Proposed Procedure to an Existing Building  
The proposed design procedure was applied to the retrofitting of a real building designed according to the 1964 Italian Code (Figure 6: ante operam; Figure 7: post operam) to test a real case characterized by real materials and geometric boundary conditions. Figure 5: Flowchart for the design procedure of additional dissipative structures (ADSs). The structure is a regular seven-story RC-framed building, and retrofitting was conducted to achieve a seismic upgrade of up to 60% of the seismic demand required for a new building, with the same function to be realized at the same site, according to Italian NTC 2018 (Italian technical code D.M. 2018, currently in effect in Italy) [30]. In accordance with the proposed approach, incremental modal pushover analyses have been conducted to derive capacity curves and assess the structural responses in both the longitudinal and transverse directions. This paper presents the longitudinal analysis for concision, as this analysis holds the most significance. The chosen target displacement, denoted as \(D^{*}\), in the ADS design procedure corresponds to achieving an interstory drift not exceeding 0.005 times the interstory height (\(D_{0.005}\), where \(h_{i}\) represents the interstory height). This interstory limit is reached before the collapse of the top displacement, \(D_{s,u}\), is attained (\(D^{*}=D_{0.005}<D_{s,u}=70\) mm). This procedure converged after four iterations. As mentioned, the choice of the target displacement (\(D^{*}\), the limit displacement of the selected control point) was made by identifying the condition under which the interstory-drift limit (\(D_{0.005}\)) was reached at any level of the building. It is emphasized that such a condition may be influenced by the boundary conditions chosen between the dissipative structure and the existing building, as well as by their respective stiffness relationships. The modeling that was performed, was updated at each iteration, automatically taking into account what has been said, and, therefore, the value of the target displacement could be redefined at each iteration based on a different evolution of interstory drifts. Similarly, the use of modal or multimodal pushover analysis allows for an evaluation that is related to the evolution of the structural system corresponding to each iteration. In this case, the connection between the tower and the building was achieved using pinned struts designed to transfer only tensile-compressive forces. The dissipative system was installed at the base of the tower, where, thanks to the presence of a spherical hinge, the vertical translations of the base perimeter nodes of the tower itself are utilized (A detailed discussion of this or other possible solutions will be presented in further studies.). As depicted in Figure 8, the performance point before the retrofitting is \(D_{S,pp}=100\) mm (while the collapse displacement is \(D_{s,u}=70\) mm), with a base shear of \(V_{S,pp}=3200\) kN. In contrast, for the retrofitted structure, at the end of the fourth iteration, the performance point corresponds to \(D_{S+T,pp,4}=65\) mm and \(V_{S+B,pp,4}=5250\) kN. Figure 9 provides a comprehensive illustration of how the retrofitting system enhances the building's safety. Not only does the performance point align with the desired target but  
Figure 7: **(a,b)** Planar and 3D views of the retrofitted building (A\({}_{1}\), A\({}_{2}\), and A\({}_{3}\) are the designed ADSs); **(c)** detail of the base of an ADS. also the base shear absorbed by the tower's system significantly reduces the seismic forces absorbed by the existing foundations, which are often challenging to retrofit. The overall increase in the base shear at the performance point is from 3200 to 5250 kN, distributed as follows: 2367 kN in the existing foundations (a 28% reduction) and 3899 kN in the ADS foundations of the three towers (refer to Figure 9).