Enhancement of nonlinear signal-based control to estimate earthquake excitations from absolute acceleration responses of nonlinear structures
Enhancement of nonlinear signal-based control to estimate earthquake excitations from absolute acceleration responses of nonlinear structures
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DOI：
10.1016/j.ymssp.2022.109486
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发表时间：
2022
影响因子：
8.4
通讯作者：
R. Enokida
中科院分区：
文献类型：
--
作者：
R. Enokida
本文建立了地震和结构工程中具有非线性滞回特性的多层结构的反演方法。基于响应和结构信息准确重构输入信号的逆方法，由于非线性特性的严重程度和结构的复杂性，一直具有挑战性。非线性信号控制（NSBC）可以在线性模型完全可逆的情况下实现对非线性结构响应的精确输入估计。然而，当无法对线性模型进行精确反演时，其估计精度会降低，需要进行近似。本研究介绍了一种由三种NSBC增强组成的控制器设计，即使在反演需要近似时也能实现准确的输入估计；在非线性结构的绝对坐标下用加速度估计地震激励就是一个典型的例子。第一个改进是改进了用于将不适当的逆模型转换为适当模型的微分器。第二种是零刚度设计，其中线性模型中所有层的刚度有意设置为零。第三是在常规NSBC控制器中加入内部误差反馈动作。通过对受地震激励的非线性2/4自由度（2/4DOF）系统的输入估计进行数值模拟，验证了这些增强的有效性。改进后的NSBC从一个已知的非线性2/4自由度系统的绝对加速度响应中成功地估计出地震激励，准确度为100%。本文还分析了该方法在非线性结构上实现预定响应估计地震激励的潜在应用。
This study constructs an inverse method for multi-storey structures with nonlinear hysteretic characteristics commonly used in earthquake and structural engineering. Constructing the inverse methods, which accurately reconstruct an input signal from a response and structural information, has been challenging owing to the severity of the nonlinear characteristics as well as structural complexity. Nonlinear signal-based control (NSBC) can achieve the exact input estimation from a nonlinear structural response when its linear model is exactly invertible. However, its estimation accuracy decreases when the exact inversion of the linear model is impossible, and an approximation is required. This study introduces a controller design consisting of three enhancements of NSBC to realise accurate input estimation even when the inversion requires an approximation; the estimation of an earthquake excitation from acceleration in the absolute coordinates of nonlinear structures is a typical example. The first enhancement is the improvement of a differentiator used to convert an improper inverse model into a proper one. The second is the zero-stiffness design wherein the stiffness of all storeys in the linear model is intentionally set to zero. The third is the addition of inner-error feedback actions to conventional NSBC controllers. The effectiveness of these enhancements is examined via numerical simulations of the input estimations of nonlinear 2/4-degree-of-freedom (2/4DOF) systems shaken by an earthquake excitation. The enhanced NSBC successfully estimates the earthquake excitation with 100% accuracy from one known absolute acceleration response of the nonlinear 2/4DOF systems. Its potential application for estimating earthquake excitations by realising a predetermined response on nonlinear structures is also analysed.