Steel bracings are one of the most widely used systems for resisting transverse loads in the design and retrofit of concrete and steel structures. This paper reports on an experimental and numerical study of the effects of core steel and the distance of the core from the casing on the behaviour of buckling-restrained braces. Laboratory models of six braces with a core made from conventional ST37 steel or ST37-n steel (softened at a temperature of 1000° using the O'Neill method) with a core–casing distance of 0, 2 or 3 mm were designed. The experimental results showed that, compared with the brace made from ST37 steel, the use of ST37-n steel resulted in a reduction of 32% in the tensile and compressive strengths of the brace. An increase in the core–casing distance in the ST37 and ST37-n braces resulted in reductions in the brace bearing capacity and energy dissipation by 26% and 52%, respectively. An increase in the core–casing distance to more than 2 mm resulted in loss of symmetry and stability of the hysteresis behaviour of the brace; in addition, distortion due to brace local buckling under pressure also intensified.

中文翻译：

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装有钢和聚酰胺套管的抗屈曲支撑性能

钢支撑是在混凝土和钢结构的设计和改造中用于抵抗横向载荷的最广泛使用的系统之一。本文报告了关于核心钢和核心与套管的距离对屈曲约束支撑行为的影响的实验和数值研究。设计了六个支架的实验室模型，其核心由传统的 ST37 钢或 ST37-n 钢（使用 O'Neill 方法在 1000° 的温度下软化）制成，核心 - 套管距离为 0、2 或 3 毫米。试验结果表明，与ST37钢制成的支架相比，使用ST37-n钢支架的抗拉抗压强度降低了32%。ST37 和 ST37-n 支撑中芯-套管距离的增加导致支撑承载力和能量耗散分别降低了 26% 和 52%。芯-套管距离增加到超过 2 mm 会导致支架滞后行为的对称性和稳定性丧失；此外，由于支撑在压力下局部屈曲引起的变形也加剧了。