## 7 Conclusions  
This paper aims at assessing the accuracy of NLSAs for analyses of RC buildings retrofitted with hysteretic dampers by means of a parametric study conducted on two regular buildings of either three or six stories. As a matter of fact, no dedicated guidance exists either in the Italian Building Code or in the European code for practitioners who must tackle the design of damping systems for enhancing the seismic performance of buildings, including any instruction on the type of analyses to be performed. The study intends to delve deeper into this gap by providing a first insight into the topic. To this end, engineering demand parameters such as maximum horizontal displacement on the top of the building, maximum inter-story drift ratio, and maximum base shear are calculated and compared to the values predicted by NLTHAs with natural accelerograms. Eventually, the study is extended to NLTHAs using artificial accelerograms. The main results of the study are summarized in the next points:  
1. When referring to the calculation of the total base shear forces, NLSAs can provide acceptable results at significantly lower computational cost compared to NLTHAs. Therefore, they can be suitable when the effectiveness of the retrofit design is evaluated comparing internal actions with capacities; the accuracy of the analyses seems to be not substantially affected by the mechanical characteristics of dissipative braces;
2. NLSAs provide fair predictions of inter-story drift only for dampers with low or moderate-low ductility (e.g., \(\mu_{DB}\leq 5\)); the accuracy quickly deteriorates as \(\mu_{DB}\) increases, and the error can be higher than 100% when \(\mu_{DB}\geq 10\). Even in case, in derogation to the code, a damping reduction factor \(\eta<\) 0.55 is considered, the deviation can be unacceptable, leading to an extremely overconservative design;
3. The study was unconclusive regarding the accuracy of NLSAs in predicting absolute displacements, even if it suggests that the analyses underestimate the displacement for small \(\mu_{DBs}\) and overestimate for high \(\mu_{DBs}\);
4. Results of NLTHAs are significantly affected by the set of accelerograms used, either artificial or natural, with absolute deviations on the order of up to 30%; the consistency between the analyses depends on the characteristics of the building and of the examined seismic scenario. Though the results are restricted to two regular RC buildings and two seismic scenarios, the study has the merit, according to the authors' opinion, of highlighting some limitations of non-linear static analyses for RC buildings retrofitted with hysteretic dampers, pointing out the conditions where a fair accuracy can be expected and when not. It is therefore hoped that the next code revision will introduce practical recommendations for carrying out seismic analyzes of structures retrofitted with dissipative bracing, specifying the limits of applicability of the various methods. Furthermore, the code should also clarify the methods for performing non-linear dynamic analyses, recommending the accelerograms to be used. As shown in the study, sets of artificial and natural accelerograms, considered equivalent at a regulatory level, can produce significantly different results. Conceptualization, E.B. and V.Q. ; methodology, E.B. and V.Q. ; software, E.B. ; investigation, E.B. ; data curation, E.B. ; writing--original draft preparation, E.B. ; writing--review and editing, V.Q. ; visualization, E.B. ; supervision, V.Q. All authors have read and agreed to the published version of the manuscript. This research has been developed within the MUSA--Multilayered Urban Sustainability Action--project, funded by the European Union--NextGenerationEU under the National Recovery and Resilience Plan (NRRP) Mission 4 Component 2 Investment Line 1.5: Strengthening of research structures and creation of R&D \"innovation ecosystems\", setup of \"territorial leaders in R&D\".