Shape memory alloys (SMAs) have found several applications in earthquake-resilient structures. However, because of high material costs, their implementation on industry projects is still limited. Developing design approaches that minimize the use of expensive SMAs is critical to facilitating their widespread adoption in real structures. This paper proposes a performance-based seismic design optimization procedure for self-centering steel moment-resisting frames (SC-MRFs) with SMA-bolted endplate connections. The topology optimization uses a metaheuristic algorithm to minimize the frame's total cost, including the initial construction and expected repair costs. The design variables are the steel beam and column sections, SMA connection properties, and the topology of the SMA connections. Different constraints are considered, such as the constructability of the chosen steel sections, member strengths, performance-based design, Park-Ang damage index, and strong-column weak-beam requirements. Furthermore, the seismic safety of optimal designs is assessed by calculating adjusted collapse margin ratios according to FEMA-P695. An illustrative optimization study using three- and nine-story SC-MRFs is presented. The optimal SC-MRFs are then assessed in terms of cost and seismic performance. The results confirm the effectiveness of the proposed optimum design, which minimizes the use of SMAs while ensuring improved seismic performance. The case studies show that the optimal placement of SMA connections can reduce the total cost by up to 71% and 61% for the three- and nine-story SC-MRFs, respectively, compared to nonoptimal frames. Moreover, the optimal SC-MRFs exhibit more uniform drift distributions, lower residual story drifts by up to 96%, and increase collapse capacity by up to 102%.

中文翻译：

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基于 SMA 连接的自定心钢矩框架的基于性能的最佳抗震设计

形状记忆合金（SMA）在抗震结构中有着多种应用。但由于材料成本较高，其在工业项目上的实施仍受到限制。开发最大限度地减少昂贵 SMA 的使用的设计方法对于促进其在实际结构中的广泛采用至关重要。本文提出了一种基于性能的抗震设计优化程序，用于具有 SMA 螺栓端板连接的自定心钢抗弯框架 (SC-MRF)。拓扑优化使用元启发式算法来最小化框架的总成本，包括初始构造和预期维修成本。设计变量包括钢梁和钢柱截面、SMA 连接属性以及 SMA 连接的拓扑。考虑不同的约束条件，例如所选型钢的可施工性、构件强度、基于性能的设计、Park-Ang 损伤指数以及强柱弱梁要求。此外，根据 FEMA-P695，通过计算调整后的倒塌裕度比率来评估最佳设计的地震安全性。提出了使用三层和九层 SC-MRF 的说明性优化研究。然后根据成本和抗震性能评估最佳 SC-MRF。结果证实了所提出的优化设计的有效性，该设计最大限度地减少了 SMA 的使用，同时确保了抗震性能的提高。案例研究表明，与非最佳框架相比，SMA 连接的最佳布局可以将三层和九层 SC-MRF 的总成本分别降低高达 71% 和 61%。此外，最佳 SC-MRF 表现出更均匀的漂移分布，将残余层位漂移降低高达 96%，并将抗倒塌能力提高高达 102%。