未知地震激励下结构恢复力及质量非参数化识别

NONPARAMETRIC IDENTIFICATION FOR STRUCTURAL RESTORING FORCE AND MASS UNDER UNKNOWN EARTHQUAKE EXCITATIONS

地震作用过程中结构恢复力是描述结构损伤发生发展过程定量描述的基础,更有助于描述结构在地震中破坏模式的演化。该文研究地震激励下结构部分质量及动力响应信息未知时,结构非线性恢复力、质量以及未知加速度时程的非参数化识别方法。首先,根据部分已知动力响应测量和质量信息,识别地震加速度时程。随后,利用记忆衰退全局加权迭代扩展卡尔曼滤波算法,引入幂级数多项式表征结构恢复力,实现了结构质量与非线性恢复力的非参数化识别。将具有非线性恢复力的磁流变阻尼器中引入到一个剪切型多自由度结构构成非线性系统,考虑测量噪声的影响,通过数值模拟验证了在噪声及较大质量初始误差情况下该方法识别结构质量、非线性恢复力及地震动加速度时程的识别效果。

The nonlinear restoring force(NRF) after earthquakes can be used to directly describe the initiation and development of structural damages and the variation of structural damage pattern. In this study, a nonparametric identification approach for structural nonlinear restoring force, mass and seismic acceleration using partially available measured dynamic responses and partial mass is proposed and is numerically validated with multi-degree-of-freedom(MDOF) structure equipped with nonlinear members. Firstly, the time history of ground motion is identified using dynamic responses measurement and mass information at limited degrees of freedom(DOFs). Secondly, the unknown structural mass and the time history of NRF are identified with an extended Kalman filter with memory fading technique and weighted global iteration method(EKF-MF-WGI) in a nonparametric way, where a power series polynomial(PSP) is employed to model structural NRF. Numerical study with a MDOF nonlinear structure equipped with a Magnetoreheological(MR) damper is carried out considering measurement noises and different initial mass estimation errors. The results show that the structural mass, NRF in time domain and seismic acceleration can be identified effectively by the proposed approach.