# Development of a New Rubber Buckling-Restrained Brace System for Structures
## 11 Conclusions  
In this study, a prototype of the Rubber Buckling-Restrained Brace (RBRB) was designed, developed, and manufactured for structures subjected to vibrations. The RBRB employs hyper-elastic rubber between the concrete and core to enhance the generated device's resistance force under both compression and tension. To evaluate its performance, the RBRB prototype was fabricated and tested experimentally using a dynamic actuator. Additionally, a prototype of a conventional Buckling-Restrained Brace (BRB) was fabricated and tested to serve as a benchmark for assessing the RBRB's performance. Based on the test results, analytical models for Buckling-Restrained Braced Frames (BRBF) and Rubber Buckling-Restrained Braced Frames (RBRBF) were developed for use in finite element simulations. A performance-based seismic design method tailored for frames equipped with RBRB devices was then developed and applied to the design of a seven-story steel building furnished with both BRB and RBRB devices. The following specific conclusions are drawn based on the results achieved:  
1. The experimental dynamic cyclic tests showed that the maximum resistance of RBRB was 224 kN with 42 mm displacement. 2. Implementing rubber in designing the RBRB system reduced the weight of the brace by 30% in comparison to BRB. 3. Numerical simulation indicated the advantages of furnishing the structure by RBRB over BRB and bare frame by applying the PBD method in nonlinear time history analysis and pushover. 4. Implementing RBRB decreased the maximum story displacement by up to 80.6% in comparison to a bare frame, which is about 34.68% more than BRB performance, in TH analysis. 5. RBRB also reduced the maximum drift ratio by about 85-90% and 48% on average, compared to the bare frame and BRBFs, respectively. 6. Base shear response was increased by furnishing the steel structure by RBRB. The maximum base shear response observed in the bare frame was 1460 kN, whereas the consistent value reported for BRBFs was 2335 kN, and it was 3046 kN in RBRBFs, which showed a 108.63% improvement in comparison with the bare frame and 30.45% more than BRBF. 7. Top-story displacement in the non-braced structure decreased by 80.6% using RBRB as a bracing system, which is around 35% more than BRBFs. 8. The performance evaluation of the structure also demonstrated an increase in the amount of dissipated energy by RBRBFs over 505 kN-m, which was 37.43% more than the bare frame and BRBFs. 9. A pushover analysis indicated the superior behavior of RBRBFs over BRBFs and the bare frame in the case of plastic hinge reduction. The results showed that about 45% of the hinges in bare frames are not acceptable and are not able to fulfill the performance level. By implementing a BRB bracing system, this amount was reduced by about 30%; however, RBRB decreased this value to less than 2%. 10. Also, by analyzing the pushover results, it can be seen that the failure number of BRBs was 37 out of 84; this value was only 9 for RBRBs, which is 75% less than BRBs. 11. By providing additional resistance, RBRBs help improve the overall stability of the structure, preventing excessive deformation in the event of large seismic forces. Thisstability reduces the likelihood of second-order moments that can amplify displacements and increase the potential for structural damage. Hence, the results showed that the RBRBF has the ability to effectively enhance the performance of the building in intense seismic hazards in comparison to BRBF and is able to protect a structure during a severe earthquake by its hybrid performance. Conceptualization, N.O. and F.H. ; Methodology, N.O. and F.H. ; Software, N.O. ; Formal analysis, N.O. ; Investigation, N.O. ; Resources, F.H. ; Data curation, N.O. ; Writing--original draft, N.O. ; Writing--review and editing, F.H. ; Visualization, N.O. ; Supervision, F.H. ; Project administration, F.H. ; Funding acquisition, F.H. All authors have read and agreed to the published version of the manuscript. There is no funding for this research work. Not applicable.