【摘要】：本文在全面回顧結(jié)構(gòu)損傷識別方法的基礎(chǔ)上,提出使用信息熵理論對基于振動的混凝土結(jié)構(gòu)進(jìn)行損傷識別,部分解決目前損傷識別領(lǐng)域存在的若干關(guān)鍵技術(shù)問題,為混凝土結(jié)構(gòu)的健康監(jiān)測提供配套判據(jù)。 根據(jù)信息熵理論,以自功率譜熵為例提出適合分析混凝土結(jié)構(gòu)損傷的熵指標(biāo)函數(shù)構(gòu)建方法。通過兩根不同的鋼筋混凝土簡支梁試驗,驗證自功率譜熵對基于振動的混凝土結(jié)構(gòu)的損傷識別效果。對比研究自功率譜熵和功率譜熵在損傷識別方面的異同點,通過實驗研究論證本文提出方法的優(yōu)勢。對原始的振動信號添加不同強(qiáng)度的噪聲,考察自功率熵的抗噪能力。 改進(jìn)近似熵理論的程序編制方法,提升其計算效率。通過自功率譜密度函數(shù)對衰減信號進(jìn)行分類,針對不同的信號模式提出不同的近似熵計算方法進(jìn)行結(jié)構(gòu)的損傷識別。使用相關(guān)函數(shù)將不具規(guī)則性的衰減信號轉(zhuǎn)化成具有規(guī)則性的互相關(guān)時間序列,采用數(shù)值模擬結(jié)合試驗的方法論證對衰減信號引入近似熵理論的可行性。試驗研究表明,利用近似熵理論對混凝土結(jié)構(gòu)進(jìn)行損傷識別時,具有很強(qiáng)的敏感性和抗噪能力。 引入改進(jìn)前和改進(jìn)后的線性化傳遞熵理論,利用梁上的加速度信號進(jìn)行動力損傷識別研究。利用Abaqus軟件分析只在主平面內(nèi)彎曲振動的混凝土簡支梁,通過折減指定單元彈性模量的方法模擬梁的彈性損傷�；诹荷隙帱c的加速度信號,利用核密度估計方法驗證了直接使用線性化傳遞熵理論的合理性。通過定義合適的損傷指標(biāo),表明改進(jìn)的線性化傳遞熵在對混凝土結(jié)構(gòu)進(jìn)行損傷識別時具有很強(qiáng)的敏感性和魯棒性。 基于Matlab軟件對承受高斯激勵的Duffing軟彈簧振子進(jìn)行數(shù)值研究,計算傳遞熵的解析解,并以此驗證線性化傳遞熵以及核密度估計傳遞熵的合理性。通過調(diào)整非線性因子模擬系統(tǒng)受不同程度的非線性損傷,利用傳遞熵結(jié)合替代數(shù)據(jù)方法對該系統(tǒng)進(jìn)行非線性損傷識別,識別結(jié)果表明該方法可有效的捕獲系統(tǒng)的非線性特征。基于Abaqus軟件,分析一根帶裂縫的混凝土簡支梁在高斯激勵下的振動特性,以裂縫的長度模擬結(jié)構(gòu)的非線性損傷程度,結(jié)合替代數(shù)據(jù)方法,對連續(xù)系統(tǒng)進(jìn)行非線性損傷識別。 通過3根不同的鋼筋混凝土簡支梁試驗,驗證傳遞熵結(jié)合改進(jìn)的替代數(shù)據(jù)方法對實際結(jié)構(gòu)的非線性損傷識別效果。通過定義合適的損傷指標(biāo),量化該方法的損傷識別效果,使用完整梁和缺陷梁驗證該方法對不同損傷模式的識別能力。從采樣頻率、抗噪能力以及激勵方式等角度,驗證傳遞熵結(jié)合替代數(shù)據(jù)方法在損傷識別時的魯棒性。 全文結(jié)合理論分析、數(shù)值模擬和試驗研究,驗證了幾個不同的信息熵指標(biāo)在混凝土結(jié)構(gòu)損傷動力識別方面具有的可靠性和優(yōu)勢,旨在為混凝土結(jié)構(gòu)的損傷識別領(lǐng)域提供一種新的、較為可行的研究思路。
[Abstract]:Based on a comprehensive review of structural damage identification methods, this paper proposes to use information entropy theory to identify concrete structures based on vibration, which partly solves some key technical problems in the field of damage identification. It provides a supporting criterion for the health monitoring of concrete structures. According to the theory of information entropy, taking the self-power spectral entropy as an example, a method of constructing entropy index function suitable for analyzing the damage of concrete structures is proposed. Through two different tests of simply supported reinforced concrete beams, the effect of self-power spectral entropy on damage identification of concrete structures based on vibration is verified. The similarities and differences between self-power spectral entropy and power spectral entropy in damage identification are compared and studied, and the advantages of the proposed method are demonstrated by experimental research. The noise resistance of self-power entropy is investigated by adding different intensities of noise to the original vibration signal. The programming method of approximate entropy theory is improved to improve its calculation efficiency. The attenuated signals are classified by self-power spectral density function, and different approximate entropy calculation methods are proposed for structural damage identification for different signal modes. The non-regular attenuation signal is transformed into a regular cross-correlation time series by using the correlation function. The feasibility of introducing approximate entropy theory to the attenuated signal is demonstrated by using the method of numerical simulation and experiment. The experimental results show that the approximate entropy theory has strong sensitivity and anti-noise ability in damage identification of concrete structures. The linear transfer entropy theory before and after improvement is introduced, and the dynamic damage identification is studied by using the acceleration signal on the beam. The simply supported concrete beams with bending vibration only in the main plane are analyzed by Abaqus software, and the elastic damage of the beams is simulated by reducing the elastic modulus of the specified element. Based on the acceleration signal of multiple points on the beam, the rationality of using the linear transfer entropy theory directly is verified by the kernel density estimation method. By defining the appropriate damage index, it is shown that the improved linear transfer entropy has strong sensitivity and robustness in damage identification of concrete structures. Based on Matlab software, the numerical study of Duffing soft spring oscillator excited by Gao Si is carried out, and the analytical solution of transfer entropy is calculated, and the rationality of linear transfer entropy and kernel density estimation transfer entropy is verified. By adjusting the nonlinear factor to simulate the system subjected to different degrees of nonlinear damage, the transfer entropy combined with alternative data method is used to identify the nonlinear damage of the system. The identification results show that the method can effectively capture the nonlinear characteristics of the system. Based on Abaqus software, the vibration characteristics of a simply supported concrete beam with cracks under Gao Si excitation are analyzed. The nonlinear damage degree of the structure is simulated by the length of cracks, and the nonlinear damage identification of continuous system is carried out combined with the alternative data method. Through the tests of three different reinforced concrete simply supported beams, the effect of transfer entropy combined with improved alternative data method on nonlinear damage identification of practical structures is verified. By defining the appropriate damage index, the damage identification effect of the method is quantified, and the complete beam and defect beam are used to verify the recognition ability of the method to different damage patterns. From the point of view of sampling frequency, anti-noise ability and excitation mode, the robustness of transfer entropy combined with alternative data method in damage identification is verified. Combined with theoretical analysis, numerical simulation and experimental research, this paper verifies the reliability and advantages of several different information entropy indexes in damage dynamic identification of concrete structures. The purpose of this paper is to provide a new and feasible research idea for the field of damage identification of concrete structures.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：TU317;TU37

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本文編號：2496555