地震作用下防屈曲支撑减震结构附加有效阻尼比计算及变化规律研究

Calculation of the additional damping ratio of buckling-restrained brace structure and its variation under earthquake

基于《建筑消能减震技术规程》(JGJ 279-2013)的附加有效阻尼比计算方法,推导防屈曲支撑(Buckling-Restrained Brace,BRB)减震结构等效单自由度体系的附加有效阻尼比计算式,分析主体结构处于不同工作阶段附加有效阻尼比变化规律,并用自由振动衰减法验证其变化规律的正确性。结果表明,主体结构弹性时,附加有效阻尼比随结构变形增加先增大后减小;主体结构塑性时,BRB附加给结构的有效阻尼比与结构屈服后刚度有关。讨论阻尼器型BRB(记为第Ⅲ类)设计原则,并分析结构第一阶段抗震设计时附加有效阻尼比的取值原则。

Based on the calculation method in ＂Technical specification for seismic energy dissipation of building＂ （JGJ 279-2013 ）, an additional effective damping ratio formula for single-degree-of-freedom system with buckling restrained braces was derived and the calculated damping ratios were analyzed under different conditions. The results were verified by the comparison with the results by the free vibration decrement method. The results show that：before the structure yields, the additional effective damping ratio increases at first and then decreases with the increment of structural deformation, and after the structure yields, the additional effective damping ratio varies with the stiffness of structure. The design principle for the buckling restrained brace and the selection method of the additional effective damping ratio were also discussed.