# Development of a New Rubber Buckling-Restrained Brace System for Structures
## 1 Introduction
(2016) developed a bamboo-shaped BRB, and the behavior of this BRB was studied by conducting experimental testing. The results demonstrated its good performance in dissipating energy. Also, it was concluded that the low-fatigue performance of the device depends on the length [9]. Various cross-sections have been proposed by [PERSON] et al. (2008) [10] for core energy dissipation. [PERSON] used BRBs with concrete fillers and square steel tubes [11]. They found out that while BRB is implemented in frames and structural members subjected to the bending moment, global buckling would not occur if the Euler load of the steel tube is greater than the yield strength of the core. Buckling-Restrained Braces have been studied widely as (1) independent members, (2) members placed in sub-assemblings, and (3) as an anti-seismic brace in structures. As singular members, BRBs illustrated high energy dissipation ability in the case of hysteretic behavior with full, stable loops [12; 13]. Various core section configurations, restrainers, and materials have been tested [14; 15]. The results showed that when mortar was chosen as a restrainer filler in BRB and the core element shape was rectangular or cruciform, mild or low-yield steel was formed. Also, common failure modes have been investigated, such as global buckling of the brace [16; 17]; core local buckling, which happens as a result of higher modes of failure [18; 19]; and buckling in un-bound zones of BRB like both ends of a device, where the core is not efficiently restrained [20]. Some other failure origins are cumulative plastic ductility [21; 22], connections, and joints [10; 23; 24]. If it is not possible to control these failures, they may have a significant effect on the structure of global response [24]. The sub-assemblage testing procedure was conducted on BRBs to assess their lateral resistance capability, particularly their connection ends while subjected to rotations [6; 25]. Acceptable responses should be within the levels of drift design based on standards. However, for demands outside these limits, failures have been identified in the connections and joints due to gusset plate out-of-plane deformation. [PERSON] et al. (2012) developed a dual gusset plate to improve the stability of the BRB connection. As a result, connections required specific studies that are beyond the scope of this research [26]. Experimental research on structures furnished by BRB is limited. Mainly, shaking table experiments are valuable due to reliable results in evaluating the structure's response under dynamic loading [26; 27; 28; 29; 30; 31; 32; 33; 34]. [PERSON] and [PERSON] (2009) conducted an experimental test on a scaled model on a shaking table in the US for a single-bay three-story steel structure furnished by BRB and a bare frame. The experimental results showed a 70% decrease in lateral displacements and inter-story drifts, but the accelerations remained unchanged. Also, they recorded an increase in the damping ratio, from 2% in the bare frame to about 5% in BRBFs [35]. A joint study was operated by the National Center for Research on Earthquake Engineering at the University of Michigan, USA (2004) [36], and the main aim of the study was to present a suitable method to find the base shear. [PERSON] et al. (2006) developed a design process for the BRBFs by means of energy spectrum hysteresis. In this method, it is assumed that structural main elements (beams and columns) are under gravity load and remain in an elastic stage, and the energy is dissipated by BRBs. Therefore, it is required and necessary for new proposed technology to have experimental and numerical studies [37]. [PERSON], [PERSON], and [PERSON] (2007) [38] conducted comprehensive research on BRBs and illustrated some of the advantages and limitations of the lateral bracing system, as follows. 1. Advantages.