非线性系统的结构荷载识别

发布时间：2018-02-09 08:05

本文关键词： 健康监测非线性系统动力响应荷载识别模型修正方法　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为结构健康监测的重要组成部分之一,系统识别技术正在被众多的学者所关注。在实际工程中,外荷载激励通常都是未知的,能否正确估计外激励的形式和大小直接决定了系统识别的精度。另一方面,非线性现象在实际工程结构中普遍存在,对非线性结构采用线性模型进行仿真分析将不可避免地引入误差。因而,本文针对非线性系统,对结构进行荷载识别。本文首先研究了结构中典型的非线性特性,及非线性分析方法。第一,对存在非线性构件的结构系统研究了等价线性化方法,将非线性系统等价成为一个线性系统来求解结构动态响应,并用于系统识别。第二,本文针对刚度—位移非线性关系以及应力—应变非线性关系,推导了这两种非线性条件下结构动力分析方法,求解了两种非线性条件下结构动力响应用于系统识别。最后,采用数值算例验证了上述两种非线性分析方法分析结果的正确性与精确度。并应用ANSYS软件建立了一段90m长的地铁隧道模型,对此模型进行了非线性分析,研究了此模型在线性条件下和非线性条件下各部位的位移,讨论了土体非线性对整体隧道结构的影响。本文研究了一种基于模型修正理论的系统外荷载的识别方法。在状态空间域内,将系统外荷载转化为切比雪夫正交多项式,通过识别切比雪夫正交项的系数,从而完成对系统外荷载的识别。应用该荷载识别理论完成非线性系统荷载识别方法的研究。本文针对实际结构非线性特性,研究了非线性系统的荷载识别方法,避免传统方法采用线性模型模拟实际结构带来的误差,为实际工程结构系统识别提供了一个新的思路。
[Abstract]:As one of the important components of structural health monitoring, system identification technology is being paid attention by many scholars. In practical engineering, external load excitation is usually unknown. The accuracy of system identification is directly determined by whether or not the form and magnitude of external excitation can be correctly estimated. On the other hand, nonlinear phenomena generally exist in practical engineering structures. It is inevitable to introduce errors into the simulation analysis of nonlinear structures by using linear model. Therefore, the load identification for nonlinear systems is carried out in this paper. Firstly, the typical nonlinear characteristics of structures are studied in this paper. First, the equivalent linearization method is studied for structural systems with nonlinear components. The nonlinear system is equivalent to a linear system to solve the structural dynamic response and be used for system identification. In this paper, according to the nonlinear relationship between stiffness and displacement and the nonlinear relation between stress and strain, the dynamic analysis method of structure under these two nonlinear conditions is derived, and the dynamic response of the structure under two nonlinear conditions is solved for the identification of the system. Numerical examples are used to verify the correctness and accuracy of the above two nonlinear analysis methods. A 90m long subway tunnel model is established by using ANSYS software, and the nonlinear analysis of the model is carried out. The displacement of each part of the model under linear and nonlinear conditions is studied. In this paper, the influence of soil nonlinearity on the whole tunnel structure is discussed. In this paper, a method of identifying system external loads based on model modification theory is studied. In the state space domain, the external loads of the system are transformed into Chebyshev orthogonal polynomials. By identifying the coefficients of the Chebyshev orthogonal term, the identification of the external loads of the system is completed. The load identification method of the nonlinear system is studied by using the load identification theory. In this paper, the nonlinear characteristics of the actual structure are studied. The load identification method of nonlinear system is studied to avoid the error caused by the traditional linear model to simulate the actual structure, which provides a new idea for the practical engineering structural system identification.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU317

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