基础隔震结构橡胶支座时变非线性特性识别

为了解基础隔震结构在地震作用下的性能状态,基于小波多尺度分析技术提出一种识别橡胶支座时变非线性恢复力模型的方法。首先,基于离散序列小波多尺度分析(multi-resolution analysis,简称MRA)理论,将橡胶支座时变非线性未知恢复力采用Daubechies小波多尺度分解的小波系数近似表达,将时变问题转化为时不变问题;其次,通过最小二乘法估计各尺度小波系数,将估计的小波系数进行重构获得橡胶支座的非线性恢复力;最后,进行数值模拟验证。数值算例表明,在上部结构刚度变化时,该方法可以准确识别出橡胶支座的非线性特性,同时也可以很好地识别出上部结构的时变刚度,验证了该算法的有效性和正确性。

Identification for Time-Varying Nonlinear Properties of Rubber-Bearings in Base-Isolated Buildings

To understand the performance state of rubber bearings under seismic action, a new method is proposed to identify time-varying nonlinear properties of the rubber-bearing isolated system based on wavelet multi-resolution analysis technique. First, based on the discrete sequences of wavelet multi-resolution analysis theory, the approximate unknown time-varying nonlinear restoring force of rubber bearings is expressed by the Daubechies wavelet coefficient. Then, the wavelet coefficients are estimated by the least-squares technique, and the nonlinear restoring force of the rubber bearing is reconstructed. Finally, the identification method has been applied to numerical examples. The results show that the proposed approach can accurately identify the nonlinear characteristics of rubber bearings when the superstructure stiffness changes and can also track the stiffness degradation of the superstructure, thus demonstrating its validity and accuracy.