振动台试验模型结构参数识别方法研究

发布时间：2018-04-05 07:38

本文选题：结构参数识别　切入点：模态坐标　出处：《中国地震局工程力学研究所》2017年硕士论文

【摘要】：结构模态参数识别是结构动力特性研究、结构损伤诊断和结构安全性评估等方面研究工作的基础和前提,其在机械工程、航空工程和土木工程等领域受到了广泛的关注和研究。在地震工程学领域,通过结构在实际地震中测得的响应数据来准确的识别出结构参数成为热门的研究课题,众多的模态参数识别方法及其改进算法被提出和应用。本文通过数值模拟和振动台试验地震响应记录,对多种模态参数识别方法进行了比较分析,主要研究工作和结论如下:1、对国内外结构模态参数识别方法的发展和现状进行了探讨,针对本文中用到的模态参数方法,详细介绍了其理论基础,包括物理坐标和模态坐标的相互转换、频响函数和脉冲响应函数的概念、相关函数及其应用等。2、通过一个三层平面框架模型算例,验证了自然环境激励法这一时域信号预处理方法的可行性,该方法利用结构在白噪声激励下响应的互相关函数来替代结构的自由衰减信号,并指出在相关函数计算的过程中,需要一定的原始输入数据长度来降低白噪声随机性的影响,其次要设置合理的自由衰减信号长度以降低信噪比的影响。3、重点研究了ITD、STD、ARX这三种模态参数识别方法,并应用于数值模拟结构的模态参数识别。通过数值模拟算例结果分析得出:1)三种方法在以结构地震响应为输入数据时,能准确的识别出结构频率,STD法相对于ITD法的识别精度更高,且计算速度更快;2)STD法和ITD法方法都受白噪声平稳随机性的影响,需要足够的信号长度来降低误差,ARX方法直接利用结构响应和输入数据,稳定性更高。4、以一个3层RC框架结构模型的振动台试验为研究对象,采用STD法和ARX法分别对不同工况后的试验结构模型进行了参数识别,并与试验现象进行了对比分析。结果表明:1)当结构处于完好或轻微破坏时,这两种方法对频率的识别结果比较接近,进一步说明了这两种方法及计算程序的可靠性;2)随着结构破坏的加深,结构各阶频率逐渐下降,各阶阻尼比增加,此时两种方法在阶数较低时会丢失真实模态,在阶数较高时又会产生虚假模态,阻尼比识别效果变差,方法的准确性有待改进。
[Abstract]:Structural modal parameter identification is the foundation and premise of structural dynamic characteristics structural damage diagnosis and structural safety assessment. It has been widely concerned and studied in the fields of mechanical engineering aviation engineering and civil engineering.In the field of seismic engineering, it has become a hot research topic to identify structural parameters accurately by the response data of structures measured in actual earthquakes. Many modal parameter identification methods and their improved algorithms have been proposed and applied.In this paper, several modal parameter identification methods are compared and analyzed by numerical simulation and seismic response record of shaking table test.The main research work and conclusions are as follows: 1. The development and present situation of structural modal parameter identification methods at home and abroad are discussed. The theoretical basis of modal parameter identification method used in this paper is introduced in detail.Including the transformation of physical coordinate and modal coordinate, the concept of frequency response function and impulse response function, the correlation function and its application.The feasibility of the natural environment excitation method as a time domain signal preprocessing method is verified. The cross-correlation function of the structure response under white noise excitation is used to replace the free attenuation signal of the structure, and it is pointed out that in the process of calculating the correlation function,In order to reduce the random effect of white noise, it is necessary to set a reasonable free attenuation signal length to reduce the influence of signal-to-noise ratio (SNR) .3.Three modal parameter identification methods (ITDX / STDARX) are studied.And applied to the modal parameter identification of the numerical simulation structure.The result of numerical simulation shows that the three methods can accurately identify the frequency of the structure compared with the ITD method when the seismic response of the structure is taken as the input data, and the accuracy of the three methods is higher than that of the ITD method.The speed of calculation is faster. Both the ITD method and the ITD method are affected by the stationary randomness of white noise. It is necessary to reduce the error by using the structural response and input data directly.The stability is higher. Taking the shaking table test of a three-story RC frame structure model as the research object, the parameters of the test structure model under different working conditions are identified by STD method and ARX method, and the results are compared with the experimental phenomena.The results show that when the structure is in good condition or slightly damaged, the results of the two methods are close to each other, which further explains the reliability of the two methods and the calculation program.The frequency of each order of the structure decreases gradually, and the damping ratio of each order increases. In this case, the two methods will lose the true mode when the order is lower, and the false mode will be produced when the order is higher, the effect of the damping ratio will become worse, and the accuracy of the method needs to be improved.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU317

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