# Development of a New Rubber Buckling-Restrained Brace System for Structures
## 8 Development of Performance-Based Design Method for Structure Furnished with BRB and RBRB
### Considered Cases for Modeling  
Figures 48 and 49 indicate the schematic of how RBRB is implemented in the structure and its function under tension and compression loading.  
The steel structural plan was used to investigate the seismic response with the conventional BRB and proposed RBRB. The plan, which is symmetrical, was employed to observe the varying story drift and displacement. The number of ways in the X and Y-directions is not the same in the building; it has three bays in the X-direction and five bays in the Y-direction. All column sizes and beam sizes are assumed to be the same throughout all stories of the building, and the supports are pinned. The model was generated in commercial software ETABS v18.0.0. Pushover and time history analyses were performed for the buildings. Three different cases have been considered for this study to make a comprehensive comparison between the models in order to check the effect of bracing systems on the behavior of the building under seismic loads. Models have been made with a bare frame (without implementing any type of brace), BRBFs, and RBRBFs. The bracing system has been implemented on all sides of the building, as shown in Figure 50. In the X-direction, the bracing system was implanted as a diagonal mega  
Figure 49: (a) RBRBF under compression; (b) RBRBF under tension.  
Figure 48: Schematic of implemented RBRB in the structure.  
7.1589 m inside span, and in the Y-direction, it was implemented as an inverted chevron with a length of 4.1725 m in mid spans.  
Seismicity is an essential factor in determining the performance of the building under earthquake loading. For the seven-story steel structure used as a case study, the seismic hazard was evaluated using the following parameters.  
Seismic Zone and Location: The building is located in an area with a high seismic risk, as defined by the USGS seismic hazard maps. The region is subject to frequent moderate-to-large-magnitude earthquakes, which require structures to be designed for significant lateral loads.  
Figure 50: Cont.  
Figure 50: (**a–d**) Bracing implementation in the building. (**e**) Bracing implementation in the building. (**a**) X-direction. (**b**) Y-direction. (**c**) Section sizes, elevation view. (**d**) Three-dimensional view. (**e**) Section sizes, plan view.  
Seismic Ground Motion: The ground motions were selected from the PEER NGA database, representing various earthquake types and magnitudes. The design utilized both DBE (Design Basis Earthquake) and MCE (Maximum Considered Earthquake) ground motions to simulate a range of seismic conditions. The peak ground accelerations (PGA) for these events were scaled to match the site-specific hazard spectrum defined by the building code.  
Soil Type: The site is characterized by medium soil conditions (Site Class C) as per the NEHRP classification. The soil properties were taken into account in the dynamic analysis, affecting the building's response to seismic waves, particularly for higher frequencies.  
Seismic Hazard Parameters: The seismic design incorporated the ASCE 7-16 guidelines, which define the seismic hazard through probabilistic seismic hazard analysis (PSHA). The study considered different return periods for the earthquake events: a 2475-year event for the MCE and a 475-year event for the DBE.  
Seismic Design Procedure: The building was designed according to the performance-based seismic design (PBSD) methodology, which aims to ensure that the structure performs well under both moderate and extreme earthquake events, while minimizing the risk of collapse or significant damage.  
Table 9 shows the details of the considered building for investigation in this study.