Identification Method for Shear Building Under Unknown Seismic Excitation with Experimental Validation

针对框架结构的绝对加速度响应部分观测、地震作用未观测的情况,提出一种多层剪切框架结构诊断的方法.该方法先依次采用扩展卡尔曼估计和递推最小二乘法对1层以上结构的扩展状态向量和未知作用力进行递推;然后利用结构频率特征方程,对第1层的结构参数进行估计;最后基于数值求解一阶微分方程,识别未观测的地震作用.通过1个4层框架试验,表明该方法能够很好地识别出结构参数和地震输入.A method is proposed for the identification of multi-story shear buildings under unknown seismic excitation with partial observations of structural absolute acceleration responses.Based on sequential application of the extended Kalman estimator and the least squares estimation,structural parameters above the first story of a building can be identified.Then,structural parameters of the first story can be identified from the frequency equation.Finally,the unknown earthquake excitation can be identified via the numerical solution of a first-order differential equation.Lab experiments of a 4-story shear building on a shaking table test have validated that the proposed method can determine structural parameters and the earthquake excitation with satisfactory accuracy.国家自然科学基金(51178406

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^