隔震结构动力特性及响应对计算模型参数的敏感性研究

SENSITIVITY OF DYNAMIC RESPONSE AND CHARACTERISTICS OF ISOLATED STRUCTURES TO CALCULATION MODEL PARAMETERS

双质点系计算模型是基础隔震结构简化计算理论研究中提出过的可以考虑高阶振型作用的一类实用模型。为了掌握基础隔震结构的动力特性及响应对这类简化计算模型参数的敏感性,该文利用"基础隔震结构的力学特点"和"每一质点所有振型参与向量和必须为一"的条件,研究了双质点系简化计算模型的动力特性及地震响应对于模型质量比、周期比的敏感性,推导了模型参数的简化算式及适用范围。并用一个工程实例验证了理论推导结果。结果表明:基础隔震结构双质点系简化计算模型的动力特性对模型质量比和周期比敏感,地震响应对模型质量比和周期比不敏感;不控制简化模型的质量比和周期比将导致由Kelly提出、李中锡等改进的第二振型阻尼比失真。

Double-mass simplified calculation model, with the consideration of higher mode effects, has been established as a practical calculation model in simplified calculation research of base-isolated structures. Sensitivities of seismic response and dynamic characteristics to mass ratio and period ratio of the double-mass simplified calculation model were calculated and illustrated based on two fundamental conditions： mechanical properties of base-isolated structures and the sum of mode-participation vectors of each mass point being 1. Furthermore, the application range of the simplified calculation model and relevant formulas were derived and analyzed. An eight-story base-isolated structure was taken as one numerical example to verify results of theoretical derivation involved. Results show that the sensitivity of seismic response to period ratio and mass ratio is not more significant than that of dynamic characteristics; and the secondary modal damping ratio, obtained from formulas proposed by Kelly and later improved by scholars such as Li Zhongxi, may be seriously apart from the suitable period ratio and mass ratio of simplified calculation model.