Buckling-restrained braces (BRBs) have proven to be very effective in improving the seismic performance of existing and new structures. They provide strength, stiffness and added energy dissipation to the structure. However, being BRBs characterized by a low post-elastic stiffness, their use may lead to residual deformations hindering the building’s reparability and to excessive cumulative ductility demand possibly compromising the residual capacity of BRBs. To overcome these drawbacks, BRB frames (BRBFs) can be coupled with moment-resisting frames (MRFs) to form dual systems. If properly designed, MRFs acting as back-up frames, allow the control of the residual drifts and the optimization of the performance of the BRBs. The contribution of this study is to provide insights into the performance and residual capacity of BRBFs-MRFs dual systems and to shed light on the influence of the main BRB’s design parameters. To this end, a non-dimensional formulation of the equation of motion is introduced for a single-degree-of-freedom system, and an extensive parametric study is performed for a set of natural ground motion records with different characteristics and scaled to various intensity levels. This allows the investigation of a wide range of configurations, considering different levels of the relative strength and ductility demand of BRBFs and MRFs, and to obtain useful information for their design. Finally, two case study frames, modeled as two-dimensional nonlinear multi-degrees-of-freedom systems, are analyzed and the results compared to those obtained from the non-dimensional formulation to show the capabilities and the limitations of the adopted methodology and of the SDOF approximation.

中文翻译：

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双系统耦合抗弯屈曲支撑框架的抗震性能

屈曲约束支撑 (BRB) 已被证明在改善现有结构和新结构的抗震性能方面非常有效。它们为结构提供强度、刚度和额外的能量耗散。然而，作为具有低后弹性刚度的 BRB，它们的使用可能会导致残余变形阻碍建筑物的可修复性，并导致过度的累积延展性需求，可能会影响 BRB 的残余容量。为了克服这些缺点，BRB 框架 (BRBF) 可以与抗弯框架 (MRF) 结合以形成双系统。如果设计得当，MRF 作为备用框架，可以控制残余漂移并优化 BRB 的性能。本研究的贡献是深入了解 BRBFs-MRFs 双系统的性能和剩余容量，并阐明主要 BRB 设计参数的影响。为此，为单自由度系统引入了运动方程的无量纲公式，并对一组具有不同特征并缩放到不同强度的自然地面运动记录进行了广泛的参数研究水平。考虑到 BRBF 和 MRF 的相对强度和延展性需求的不同水平，这允许对广泛的配置进行调查，并获得对其设计有用的信息。最后，两个案例研究框架，建模为二维非线性多自由度系统，