国标Q235钢屈曲约束支撑低周疲劳试验研究

Low-cycle fatigue test of Q235 steel buckling-restrained braces

屈曲约束支撑是一种利用金属屈服滞回耗能的装置,具有性能稳定、制作方便、成本低廉等优点。通过对国标Q235钢屈曲约束支撑进行低周疲劳试验,评估其累积滞回性能,分析影响其失效模式的因素,并与国外同类型屈曲约束支撑进行对比。试验结果表明:屈曲约束支撑滞回曲线饱满,累积塑性变形远大于AISC规程的建议值;支撑屈服段内的焊缝对低周疲劳性能的影响显著,试验表明大应变幅值下焊缝影响被削弱;核心板的多波屈曲是导致屈曲约束支撑的低周疲劳性能小于核心板材的低周疲劳性能的主要原因;与同期在国外开展的屈曲约束支撑低周疲劳性能试验相比,在相同加载幅值下,国标Q235钢屈曲约束支撑表现出与SM400A钢屈曲约束支撑相当的性能,国产普通钢支撑完全可以替代同等级钢材进口屈曲约束支撑。

A buckling-restrained brace （BRB） is an energy dissipation device making use of metal yielding and its advantages include the stable energy dispersion capacity, easy construction and low-cost fabrication, etc. This paper presents the low-cycle fatigue test of Q235 steel BRB. The failure modes and the effects on its failure modes are discussed and compared with the experiments introduced in the literature. Test results show that the BRB possesses the stable hysteretic performance and its cumulative plastic deformation is much larger than the value suggested in the AISC specification. The effect of the weld in the BRB＇s yielding range on the low-cycle fatigue performance is evident. However, it was observed from the experiment that the effect of the weld is reduced due to the large strain loading amplitude. The mutli-wave buckling of the core brace member is regarded as the main reason why the low-cycle fatigue performance of BRB was lower compared to the corresponding material. Under the similar loading pattern, the performance of Q235 steel BRB is the same as the SM400A BRB. Hence, the domestic BRB can replace the imported BRB based on the low-cycle fatigue data.