## 6 Conclusions  
It is shown by the experimental and computational findings reported in this work that the TnT BRB system that was designed is successful in significantly enhancing the seismic performance of RC frames that are not up to specification. With regard to the shake table tests, it is evident that the TnT braced frame displayed significant enhancements in lateral strength, ductility, and energy dissipation capabilities when contrasted with the non-retrofitted control specimen. The latter suffered considerable damage, including joint shear failure, under much lower seismic forces.  
Further, the analytical model of TnT BRB system demonstrated superior seismic behavior compared to the conventional X-type BRB systems. It was able to achieve maximum lateral displacements that were approximately twice as large as those of the X-type BRBframe, with a difference of approximately 20 mm and 10 mm, respectively. In addition to this, the TnT brace exhibited a dissipation capacity for hysteretic energy that was much higher than that of the traditional system, with a cumulative energy dissipation that was roughly 2.5 times higher than that of the conventional system at displacement amplitudes that were equivalent.  
Both the numerical studies and the experimental data were in good agreement with one another. The numerical analyses demonstrated stable and large hysteretic loops, which are indicative of enhanced ductility and effective energy transfer. These quantitative data, taken as a whole, provide further evidence that the TnT BRB system has excellent performance, notably with regard to its capacity for deformation, its ability to dissipate energy, and its ability to promote ductility.  
Future research endeavors stemming from this study should encompass extensive parametric analyses aimed at optimizing the tube-in-tube configuration. This entails a focused examination of potential issues such as localized denting, wear due to friction, and unintended interactions between the concentric tubes. Conducting thorough investigations into the implications of tube alignment, geometric discrepancies, and friction-related phenomena would significantly aid in refining design parameters and bolstering the system's durability.  
Moreover, it is advisable to undertake field studies and prolonged monitoring of actual retrofitted structures utilizing the TnT BRB system. Such initiatives would serve to substantiate laboratory findings within authentic operational environments and foster wider acceptance and integration into seismic retrofitting methodologies. Furthermore, the exploration of advanced materials and innovative connection designs could markedly improve durability, cost-effectiveness, and ease of implementation, thereby making a noteworthy contribution to the global initiative aimed at reducing seismic vulnerabilities in at-risk building inventories.  
Conceptualization, E.O. and R.O.; methodology, E.O., R.O., O.S. and A.H.; software, R.O.; investigation, E.O.; resources, E.O. and R.O.; data curation, E.O. and R.O.; writing--original draft preparation, E.O.; writing--review and editing, E.O., O.S. and R.O.; visualization, E.O.; supervision, A.H., B.A. and J.S. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
This empirical research was carried out utilizing a shake table situated at the Allianz Teknik Earthquake and Fire Test and Training Center in Istanbul, Turkiye. The authors express their genuine gratitude to all personnel involved for their significant input. Furthermore, appreciation is conveyed to ORTAS Celik for their assistance. It is important to note that the perspectives articulated in this paper are solely those of the authors and do not inherently represent the opinions of those acknowledged.  
The authors declare no conflicts of interest.