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以国内外近年来的各类型屈曲约束支撑(BRB)的试验数据为基础,提出了与BRB承载力超强相关的应变硬化系数和拉压不平衡系数上限值的计算公式。设计并完成了7组Q235钢芯材BRB轴心受力试验,分析了超强系数与峰值应变和累积塑性应变之间的关系,研究了加载速率对超强系数的影响。结果表明:虽然离散性较大,但Q235钢芯材BRB的应变硬化系数和拉压不平衡系数均表现出随峰值应变的增大而增大的趋势。在设计中可采用建议的超强系数包络值以更加合理地考虑BRB的超强特性。BRB是位移相关型消能器,但试验中BRB试件在应变速率约为0.1/s的动力加载作用下的拉压不平衡系数明显大于相同峰值应变下静力加载试验结果,说明加载速率对BRB受压性能影响明显,对该现象有待深入研究。
Based on the experimental data of various types of Buckling Restrained Bracing (BRB) both at home and abroad, the formulas for calculating the upper limit value of strain hardening coefficient and tension-compression imbalance coefficient related to BRB bearing capacity are proposed. The BRB axial stress test of seven groups Q235 steel core was designed and completed. The relationship between super-strength coefficient and peak strain and cumulative plastic strain was analyzed and the influence of loading rate on super-strength coefficient was studied. The results show that although the dispersion is large, the strain hardening coefficient and the tension-compression unbalance coefficient of BRB steel Q235 tend to increase with the increase of peak strain. The proposed Super Coefficient Envelope value can be used in the design to more appropriately consider the superb characteristics of the BRB. BRB is a displacement-dependent energy dissipater. However, the unbalance coefficient of tension and compression of BRB specimen under dynamic loading with strain rate of about 0.1 / s is obviously higher than that of static loading test under the same peak strain, indicating that the loading rate BRB compression performance is obvious, this phenomenon needs further study.