一字形全钢防屈曲支撑耗能性能试验研究

Experimental study of buckling-restrained braces with in-line steel core plate encased in double web wide flange steel outer unit

对一种新型防屈曲支撑进行性能试验研究。该种防屈曲支撑(以下称一字形全钢防屈曲支撑)的内核为一字形钢板,外约束单元为双腹板工字形钢,中间用薄橡胶作为无黏结材料。通过对8个一字形全钢防屈曲支撑试件进行轴向循环往复加载试验,研究了防屈曲支撑的耗能性能以及不同芯材特性、支撑长度对其耗能性能的影响。结果表明:一字形全钢防屈曲支撑的构造合理,所有试件的滞回曲线稳定饱满;芯材特性和支撑长度对于该种防屈曲支撑的耗能性能均有较大影响;以SLY225为芯材的防屈曲支撑,其耗能性能、低周疲劳性能与塑性变形能力均明显优于以SN490B为芯材的防屈曲支撑;SLY225能提供45%以上的附加有效阻尼比;增加支撑长度,防屈曲支撑的塑性变形能力与低周疲劳性能均有所下降。

This paper mainly presents an experimental research on a new type of buckling-restrained brace （BRB） which uses an in-line steel plate as the core and a double-web wide flange steel member as the outer unit. A thin rubber layer is used between the core plate and outer unit as unbonded material. Uniaxial cyclic loading tests of eight BRB specimens were conducted to investigate the energy dissipation capacity of the BRBs as well as the effects of core material and brace length on the energy dissipation capacity. The results show that the structure of this new BRB is applicable and all the hysteresis curves are stable and plump. Both core material properties and brace length have significant effects on the energy dissipation capacity of the BRBs. The specimen with SLY225 as the core material has better performance such as the energy dissipation capacity, low cycle fatigue performance and plastic deformation capacity than the one with SN490B as the core material. The former can provide an additional damping ratio of 45% which is larger than the latter. It is also found that the plastic deformation capacity and the low cycle fatigue performance degrade with the increase of the brace length.