Buckling-restrained braces (BRBs) have shown their capability to provide building structures with stiffness, strength, and ductility. Estimating the seismic drifts of buckling-restrained braced frames (BRBFs) is an important design step to control structural and non-structural damage. In current practice of seismic design, the estimation of seismic drifts of BRBFs is performed by using empirical calculations that are independent upon either the type of the structural system or the design level of seismicity. In these empirical calculations, the seismic drifts are estimated by amplifying the reduced elastic drifts obtained under design lateral loading with a displacement amplification factor (DAF). The value of DAF is considered equal to the product of the response modification factor R and the inelastic displacement ratio ρ. The goal of the current research is to assess the value of ρ for low- to mid-rise BRBFs designed under low and high levels of seismicity. This goal has been achieved by conducting a series of elastic and inelastic time-history analyses pertaining to an ensemble of earthquake records on 3-, 6- and 9-story BRBFs. The results indicate that the ρ-ratio increases with an increase in design seismic intensity and an increase in experienced inelasticity. The range of ρ for low seismicity designs ranges from 0.63 to 0.9, while for high seismicity designs this range stretches from 0.83 to 1.29. It has been found that the consideration of a general ρ-ratio of 1.0 is a reasonable estimation for the design of the BRBFs considered in this study.

防屈曲支撑 (BRB) 已显示出其为建筑结构提供刚度、强度和延展性的能力。估计屈曲约束支撑框架 (BRBF) 的地震漂移是控制结构和非结构损坏的重要设计步骤。在当前的抗震设计实践中，BRBF 地震漂移的估计是通过使用独立于结构系统类型或地震活动性设计水平的经验计算来进行的。在这些经验计算中，通过使用位移放大系数（DAF）放大设计横向荷载下获得的减少的弹性漂移来估计地震漂移。DAF 的值被认为等于响应修正因子R的乘积和非弹性位移比ρ。当前研究的目标是评估在低强度和高强度地震活动下设计的中低层 BRBF 的ρ值。这一目标是通过对 3 层、6 层和 9 层 BRBF 的一组地震记录进行一系列弹性和非弹性时程分析来实现的。结果表明，ρ比随着设计地震烈度的增加和经历的非弹性的增加而增加。低地震活动性设计的ρ范围为 0.63 至 0.9，而高地震活动性设计的 ρ 范围为 0.83 至 1.29。已经发现，考虑一般的ρ-比率 1.0 是本研究中考虑的 BRBF 设计的合理估计。