地震激励下结构模态参数识别及振动台试验验证
发布时间：2018-07-15 21:07
【摘要】：地震在短时间内释放巨大的能量,容易对结构造成严重破坏。研究结构在地震激励下的参数变化,不仅可以为结构抗震设计提供指导,也可以为震后结构性能的评估提供基础。地震激励是一种天然激励,利用地震输入和结构在地震激励下的动力响应,进行模态参数识别是自然、方便的方法。对于已知地震激励和相应动力响应的结构,可以直接应用地震记录(Input-output)进行模态参数识别。对于多数实际结构,通常难以得到结构处地震输入数据,而获得结构在地震激励下的响应则相对容易,此时需要仅依据地震响应(Output-only)进行模态参数识别。本文旨在研究地震激励下的上述两类结构模态参数识别方法,并通过地震模拟振动台桥梁模型试验,对各方法进行了对比和验证。论文研究具有重要的理论意义和工程实用价值。 论文的主要研究工作和结论包括： 1.当地震激励可以观测到时,可以通过傅立叶变换得到频域内的频响函数和时域内的脉冲响应函数,通过模态参数与两种函数间的关系进行识别。详细讨论了基于地震记录(Input-output)的模态参数识别方法：分量分析法、加权最小二乘迭代法、有理分式多项式法、ITD法和时域复指数法,并自行编程实现了这些算法,应用数值模拟数据验证了各方法的有效性。 2.详细介绍了峰值法、频域分解法、PolyMAX法以及基于参考点的随机子空间识别四种仅仅基于地震响应(Output-only)的模态参数识别方法的理论过程,并通过编程实现了各算法。然后通过数值模拟数据验证了虽然地震激励不满足白噪声假定,但基于Output-only的方法识别结果仍具有较高的精度。 3.对一实际桥梁的缩尺模型进行了地震模拟振动台试验。分别采用基于地震记录(Input-output)和仅基于地震响应(Output-only)的方法进行模态参数识别,通过结果对比发现,各方法识别结果基本一致,再次验证了基于Output-only方法的有效性。 4.ITD法和时域复指数法提高了系统阶次,容易产生虚假模态,需要采用模态保证判据(MAC)剔除虚假模态。峰值法虽然计算简单、快速,但阻尼比和振型识别结果较差。PolyMAX方法和随机子空间识别都需要假定系统阶次的试算范围形成最终的稳定图,计算工作量较大,在实际使用中应综合参考几种方法的识别结果做最终判断。图46幅,表26个,参考文献75篇。
[Abstract]:The earthquake releases huge energy in a short period of time, which can easily cause serious damage to the structure. The study of structural parameters under earthquake excitation can not only provide guidance for seismic design of structures, but also provide a basis for the evaluation of post-earthquake structural performance. Seismic excitation is a kind of natural excitation. It is a natural and convenient method to identify modal parameters by using the dynamic response of earthquake input and structure under earthquake excitation. Input-output can be directly used to identify modal parameters for structures with known earthquake excitation and corresponding dynamic response. For most actual structures, it is usually difficult to obtain seismic input data, but it is relatively easy to obtain structural response under earthquake excitation. In this case, modal parameters identification is required only according to the seismic response (Output-only). The purpose of this paper is to study the identification methods of the above two kinds of structural modal parameters under earthquake excitation, and to compare and verify the methods through the model tests of shaking table bridges simulated by earthquake. The research of this paper has important theoretical significance and practical value. The main research work and conclusions are as follows: 1. When the earthquake excitation can be observed, the frequency response function in the frequency domain and the impulse response function in the time domain can be obtained by Fourier transform, and the relationship between the modal parameters and the two functions can be identified. The identification methods of modal parameters based on Input-output are discussed in detail: component analysis method, weighted least square iterative method, rational fraction polynomial method and time domain complex exponent method. The validity of each method is verified by numerical simulation data. 2. The theoretical processes of peak value method, frequency domain decomposition method, PolyMAX method and random subspace identification method based on reference point are introduced in detail. Then the numerical simulation data show that although the seismic excitation does not satisfy the white noise assumption, the method based on Output-only still has a high accuracy. The shaking table test of a practical bridge scale model is carried out. Input-output and Output-only methods are used to identify modal parameters respectively. The results show that the identification results are basically the same. The validity of the output-only method is verified again. 4. ITD method and time domain complex exponent method can improve the order of the system and easily produce false modes, so it is necessary to use the modal assurance criterion (MAC) to eliminate the false modes. Although the peak value method is simple and fast, the damping ratio and vibration pattern recognition result is poor. PolyMAX method and random subspace recognition both need to assume the trial calculation range of the system order to form the final stability diagram, and the calculation work is large. In practical use, the final judgment should be made by referring to the recognition results of several methods. There are 46 figures, 26 tables and 75 references.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3
本文编号：2125384
[Abstract]:The earthquake releases huge energy in a short period of time, which can easily cause serious damage to the structure. The study of structural parameters under earthquake excitation can not only provide guidance for seismic design of structures, but also provide a basis for the evaluation of post-earthquake structural performance. Seismic excitation is a kind of natural excitation. It is a natural and convenient method to identify modal parameters by using the dynamic response of earthquake input and structure under earthquake excitation. Input-output can be directly used to identify modal parameters for structures with known earthquake excitation and corresponding dynamic response. For most actual structures, it is usually difficult to obtain seismic input data, but it is relatively easy to obtain structural response under earthquake excitation. In this case, modal parameters identification is required only according to the seismic response (Output-only). The purpose of this paper is to study the identification methods of the above two kinds of structural modal parameters under earthquake excitation, and to compare and verify the methods through the model tests of shaking table bridges simulated by earthquake. The research of this paper has important theoretical significance and practical value. The main research work and conclusions are as follows: 1. When the earthquake excitation can be observed, the frequency response function in the frequency domain and the impulse response function in the time domain can be obtained by Fourier transform, and the relationship between the modal parameters and the two functions can be identified. The identification methods of modal parameters based on Input-output are discussed in detail: component analysis method, weighted least square iterative method, rational fraction polynomial method and time domain complex exponent method. The validity of each method is verified by numerical simulation data. 2. The theoretical processes of peak value method, frequency domain decomposition method, PolyMAX method and random subspace identification method based on reference point are introduced in detail. Then the numerical simulation data show that although the seismic excitation does not satisfy the white noise assumption, the method based on Output-only still has a high accuracy. The shaking table test of a practical bridge scale model is carried out. Input-output and Output-only methods are used to identify modal parameters respectively. The results show that the identification results are basically the same. The validity of the output-only method is verified again. 4. ITD method and time domain complex exponent method can improve the order of the system and easily produce false modes, so it is necessary to use the modal assurance criterion (MAC) to eliminate the false modes. Although the peak value method is simple and fast, the damping ratio and vibration pattern recognition result is poor. PolyMAX method and random subspace recognition both need to assume the trial calculation range of the system order to form the final stability diagram, and the calculation work is large. In practical use, the final judgment should be made by referring to the recognition results of several methods. There are 46 figures, 26 tables and 75 references.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3
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