Estimation of maximum drift of multi‐degree‐of‐freedom shear structures with unknown parameters using only one accelerometer
Estimation of maximum drift of multi‐degree‐of‐freedom shear structures with unknown parameters using only one accelerometer
复制标题
DOI：
10.1002/stc.2799
复制
发表时间：
2021-05
影响因子：
5.4
通讯作者：
Kangqian Xu;A. Mita
中科院分区：
文献类型：
--
作者：
Kangqian Xu;A. Mita
当多自由度剪切结构受到地震激励时，结构和非结构构件之间的连接可能变得松散或产生轻微的结构损伤，从而导致从健康结构中识别出的固有频率发生变化。然而，从一个传感器记录的响应中准确地重新识别固有频率并不容易。本文提出了一种根据实测的绝对响应估计结构各层间最大位移和各层相对位移时程的方法。首先，在模态坐标下给出了绝对加速度和相对位移的表达式，并推导了状态空间表达式。然后，设计了一种利用遗传算法和合理选择适应度函数来减小结构频率漂移引起的建模误差的方案。通过对固有频率变化率和遗传算法变量下界的选择进行数值模拟，研究了该方法的适用性。进一步的仿真研究了该方法的鲁棒性、安装位置和截断误差。最后，通过一个简单的实验验证了该方法的有效性。结果表明，在固有频率显著变化和GA变量搜索范围较大的情况下，该方法可以准确地估计各楼层相对位移和最大层间漂移的时间历程。此外，它对环境噪声具有鲁棒性，即使在模型仅包含较低模态响应时也表现良好。
When a multi‐degree‐of‐freedom (MDOF) shear structure is excited by seismic excitation, the connections between structural and non‐structural members may become loose or slight structural damage may arise, which cause the natural frequencies identified from the healthy structure shift. However, it is not easy to accurately re‐identify the natural frequencies from the response recorded by one sensor. This paper presents a method to estimate the maximum inter‐story drift and time histories of the relative displacement of all stories of the structure from the measured absolute response. First, the absolute acceleration and relative displacement are formulated in modal coordinates, and a state‐space expression is derived. Then, a scheme to reduce the modeling error arising from shifts in the structural frequencies is devised that uses the genetic algorithm (GA) and a reasonably chosen fitness function. The applicability of this approach was investigated by conducting numerical simulations focusing on the rate of change in natural frequencies and selection of the lower bound of GA variables. Further simulations were conducted to investigate the robustness, installation location, and truncation error of the proposed method. Finally, the proposed approach was validated in a simple experiment. The results indicate that it can accurately estimate the time histories of the relative displacement and maximum inter‐story drifts of all floors in the case of a significant change in natural frequencies and a large search range of GA variables. In addition, it is robust against environmental noise and performs well even when the model includes only lower modal responses.