旗帜形滞回模型等效阻尼比数值研究

Numerical study on equivalent damping ratio of flag-shaped hysteretic model

自复位结构在地震作用后能够恢复至初始位置,残余变形极小,其滞回模型通常呈现为旗帜形。针对旗帜形滞回模型的等效线性阻尼比开展了数值研究。通过构建一系列不同滞回参数和等效周期所对应的旗帜形非线性单自由度体系,选取大量的真实地震波记录,分别对非线性体系和等效线性体系进行动力时程计算,发现Jacobsen’s Damping Secant Stiffness(JDSS)方法所得到的等效阻尼比存在较大的误差,进而通过迭代计算得到满足误差要求的等效阻尼比,分析了不同参数对其的影响。基于JDSS方法,对数值计算结果进行参数拟合,得出了修正公式,并对其进行验证,结果表明该公式能够满足设计需要。

The self-centering structure can return to its initial position after earthquakes with small residual deformation.Its hysteretic model usually presents a flag-shape.For the equivalent damping ratio of the linearized system corresponding to the flag-shaped hysteretic model,numerical calculation was carried out in this study.By constructing a series of nonlinear single degree of freedom systems with different flag-shaped hysteretic parameters and equivalent periods,dynamic responses of the nonlinear and corresponding equivalent linear systems under a large number of seismic ground motions were calculated.It is found that there is considerable error of the equivalent damping ratio obtained by JDSS method.Accordingly,the equivalent damping ratio was obtained through iterative calculation,and the influence of different parameters on it was analyzed.Based on the JDSS method,the parameters of the numerical calculation results were fitted,and the modified formula was obtained.It is verified by calculation that the formula can meet the design needs.