Q235钢芯材屈曲约束支撑的超强特性研究

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。

Over-strength characteristics of buckling restrained braces made of Q235 steel

Based on the experimental results of various types of buckling restrained braces (BRBs) in the literature,equations of estimating the two over-strength factors of BRBs, namely the strain-hardening factor and the compressive over-strength factor, were proposed. A series of cyclic loading tests of BRBs made of Q235 steel were conducted.The effects of the peak strain, cumulative plastic strain and strain rate on the over-strength of BRBs were examined. Although the scattering is large, the test results suggest that both the over-strength factors increase with the increase of peak strains. The proposed upper bounds of the over-strength factors can be used in the practical design to better address the over-strength of BRBs. The test results also show that the compressive over-strength factors under dynamic loading of approximately 0.1/s strain rate are considerably larger than those in the static tests, indicating that the compressive behavior of BRBs are dependent on the strain rate although they are usually considered as hysteretic dampers. This effect deserves further investigations.