钢筋混凝土受弯构件动力参数识别和损伤诊断研究
发布时间：2018-09-13 06:21
【摘要】：提出本研究的意图是系统的动力性能研究及其应用,该研究可以概括为系统仿真和系统动力测试两部分,前者主要是理论研究,比如系统的动力模型、运动方程和解答,后者主要围绕实验展开,比如结构动力测试技术,系统参数识别方法。文章结合这两方面的问题展开,并着重在信号处理原理,参数识别方法上进行了深入探讨,对钢筋混凝土受弯构件进行了动力测试,依据测试数据识别得到结构的动力参数,总结测试技术和结构动力性能两方面的规律。研究的主要工作简述如下： 对钢筋混凝土受弯构件的分级静力加卸载性能进行了细致测试,得到构件随荷载增加刚度下降的真实变化曲线,结合相关研究推测构件弯曲刚度函数的主要特征,为理论研究和实际应用提供基本事实依据。首先只要当前荷载不大于结构经历过的最大荷载,受弯构件的荷载-挠度关系基本符合线性特征,依据动力测试数据识别结构动力参数,一般构件在荷载-挠度曲线上的非线性都比较弱,假设的结构模型与测试数据不符合时,多考虑其以外的其他因素,其次构件开裂截面上刚度下降所影响的区域也往往较小。 从傅立叶级数推导出离散傅立叶变换(DFT)表达式,对DFT物理意义进行了清晰完整的解释,采用不同的DFT表达式计算信号频谱时,只需相应调整频谱系数和频域坐标。在原理上澄清了频谱的对称性质,尽管有效谱线数N／2这个笼统的数字一般不会遗漏关键谱线,但有可能影响到对其他相关问题的理解,比如在频域计算过程中,会混淆数量关系；在讨论DFT物理意义的基础上进一步讨论了定频的改进方法：细化频谱分析。同时由理论推导发现了细化频谱与连续矩形窗频谱有极大相似之处,以连续矩形窗频谱曲线为样板,提出了一般保守信号细化频谱的量化特征,并在解决密集频率频谱的判定和分离的问题中得到应用。 通过细化频谱分析识别信号的频率和初相位,利用DFT的重要性质：离散卷积和反卷积原理。提出一种从自由衰减响应(FDR)中提取阻尼特性的新方法,本方法在对阻尼特性进行提取之前不需要对阻尼模型进行假设,提取FDR中各频率谐波的振幅随时间变化的时域序列,能够更加真实的揭示系统的阻尼特性,该方法主要对独立频率频谱比较适用。对于密集频率频谱,参考离散反卷积方法得到的识别结果,设定谐波参数范围和步长,把这些参数循环代入指定理论信号表达式中,寻找能使理论信号与实验信号的频域曲线最相近的参数组合确定为最优结果,实现了只用结构的响应信号识别系统模态参数的预想。 对钢筋混凝土框架、普通钢筋混凝土简支梁和组合梁进行了动力实验,依据对实验测试数据的计算结果,讨论了不同测试条件对测试结果的影响,总结了动力测试技术和结构的动力性能两方面的规律；在用动力方法对结构进行损伤诊断时,得到了模态参数随结构损伤的变化规律：各频率随损伤增加不断下降,其中高频的下降量较大,阻尼的指数衰减系数,在正常使用阶段也有随损伤增加而增加的趋势,高阶模态的趋势更大。频率和阻尼对判断结构的状态都有一定指示作用,而模态振型可以帮助判断重复模态。
[Abstract]:The purpose of this study is to study the dynamic performance of the system and its application. The study can be summarized as two parts: system simulation and system dynamic test. The former is mainly theoretical research, such as dynamic model, motion equation and solution of the system. The latter is mainly carried out around experiments, such as structural dynamic test technology, system parameter identification method. This paper combines these two problems, and focuses on the principle of signal processing and parameter identification method. The dynamic test of reinforced concrete flexural members is carried out. The dynamic parameters of the structure are identified according to the test data. The main work of the research is summarized in the aspects of testing technology and structural dynamic performance. The following are briefly stated:
The static loading and unloading performance of reinforced concrete flexural members is tested in detail, and the real change curve of the stiffness of the members decreases with the increase of load is obtained. The main characteristics of the flexural stiffness function of the members are deduced by combining with relevant research, which provides the basic factual basis for theoretical research and practical application. The load-deflection relationship of the flexural member is basically linear under the maximum load experienced by the structure. The dynamic parameters of the structure are identified according to the dynamic test data. Generally, the nonlinearity of the members on the load-deflection curve is weak. When the assumed structural model does not conform to the test data, the factors other than the load-deflection relationship should be considered, and then the cracking of the members should be considered. The decrease of stiffness on the cross section also tends to be smaller.
The expression of discrete Fourier transform (DFT) is deduced from Fourier series. The physical meaning of DFT is explained clearly and completely. When different DFT expressions are used to calculate the signal spectrum, only the spectrum coefficients and the frequency domain coordinates need to be adjusted accordingly. The symmetry property of spectrum is clarified in principle, although the general figure N/2 is the effective spectral line number. In general, the key spectral lines will not be omitted, but it may affect the understanding of other related problems, such as confusing the quantitative relationship in the frequency domain calculation process; on the basis of discussing the physical meaning of DFT, the paper further discusses the improved method of frequency determination: the refined spectral analysis. The spectrum has great similarity. Taking the spectrum curve of continuous rectangular window as a model, the quantization characteristics of general conservative signal thinning spectrum are proposed and applied to the determination and separation of dense frequency spectrum.
Frequency and initial phase of signals are identified by spectral analysis, and a new method of extracting damping characteristics from free attenuation response (FDR) is proposed based on the discrete convolution and deconvolution principle, which is an important property of DFT. The time-domain sequence of amplitudes varying with time can reveal the damping characteristics of the system more truly. This method is mainly suitable for the independent frequency spectrum. For the dense frequency spectrum, the range and step size of harmonic parameters are set according to the identification results obtained by the discrete deconvolution method, and these parameters are cyclically substituted into the specified theoretical signal expression. In the formula, the optimal result is obtained by finding the parameter combination which can make the frequency domain curve of the theoretical signal and the experimental signal the closest.
The dynamic experiment of reinforced concrete frame, ordinary reinforced concrete simply supported beam and composite beam is carried out. Based on the calculation results of experimental test data, the influence of different test conditions on test results is discussed, and the rules of dynamic test technology and dynamic performance of structure are summarized. At break time, the variation law of modal parameters with structural damage is obtained: the frequency decreases with the increase of damage, and the high frequency decreases more, the exponential damping coefficient of damping increases with the increase of damage, and the trend of high-order modal is larger. Frequency and damping have certain influence on judging the state of structure. The mode of vibration can help to judge repetitive modes.
【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU375;TU311.3
本文编号：2240335
[Abstract]:The purpose of this study is to study the dynamic performance of the system and its application. The study can be summarized as two parts: system simulation and system dynamic test. The former is mainly theoretical research, such as dynamic model, motion equation and solution of the system. The latter is mainly carried out around experiments, such as structural dynamic test technology, system parameter identification method. This paper combines these two problems, and focuses on the principle of signal processing and parameter identification method. The dynamic test of reinforced concrete flexural members is carried out. The dynamic parameters of the structure are identified according to the test data. The main work of the research is summarized in the aspects of testing technology and structural dynamic performance. The following are briefly stated:
The static loading and unloading performance of reinforced concrete flexural members is tested in detail, and the real change curve of the stiffness of the members decreases with the increase of load is obtained. The main characteristics of the flexural stiffness function of the members are deduced by combining with relevant research, which provides the basic factual basis for theoretical research and practical application. The load-deflection relationship of the flexural member is basically linear under the maximum load experienced by the structure. The dynamic parameters of the structure are identified according to the dynamic test data. Generally, the nonlinearity of the members on the load-deflection curve is weak. When the assumed structural model does not conform to the test data, the factors other than the load-deflection relationship should be considered, and then the cracking of the members should be considered. The decrease of stiffness on the cross section also tends to be smaller.
The expression of discrete Fourier transform (DFT) is deduced from Fourier series. The physical meaning of DFT is explained clearly and completely. When different DFT expressions are used to calculate the signal spectrum, only the spectrum coefficients and the frequency domain coordinates need to be adjusted accordingly. The symmetry property of spectrum is clarified in principle, although the general figure N/2 is the effective spectral line number. In general, the key spectral lines will not be omitted, but it may affect the understanding of other related problems, such as confusing the quantitative relationship in the frequency domain calculation process; on the basis of discussing the physical meaning of DFT, the paper further discusses the improved method of frequency determination: the refined spectral analysis. The spectrum has great similarity. Taking the spectrum curve of continuous rectangular window as a model, the quantization characteristics of general conservative signal thinning spectrum are proposed and applied to the determination and separation of dense frequency spectrum.
Frequency and initial phase of signals are identified by spectral analysis, and a new method of extracting damping characteristics from free attenuation response (FDR) is proposed based on the discrete convolution and deconvolution principle, which is an important property of DFT. The time-domain sequence of amplitudes varying with time can reveal the damping characteristics of the system more truly. This method is mainly suitable for the independent frequency spectrum. For the dense frequency spectrum, the range and step size of harmonic parameters are set according to the identification results obtained by the discrete deconvolution method, and these parameters are cyclically substituted into the specified theoretical signal expression. In the formula, the optimal result is obtained by finding the parameter combination which can make the frequency domain curve of the theoretical signal and the experimental signal the closest.
The dynamic experiment of reinforced concrete frame, ordinary reinforced concrete simply supported beam and composite beam is carried out. Based on the calculation results of experimental test data, the influence of different test conditions on test results is discussed, and the rules of dynamic test technology and dynamic performance of structure are summarized. At break time, the variation law of modal parameters with structural damage is obtained: the frequency decreases with the increase of damage, and the high frequency decreases more, the exponential damping coefficient of damping increases with the increase of damage, and the trend of high-order modal is larger. Frequency and damping have certain influence on judging the state of structure. The mode of vibration can help to judge repetitive modes.
【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU375;TU311.3
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