【摘要】：預(yù)應(yīng)力鋼筋混凝土簡支梁橋和連續(xù)梁橋在我國市政公路橋梁中廣泛使用,由于交通運輸能力的要求不斷提高,這些橋梁往往負(fù)荷過重,遠(yuǎn)遠(yuǎn)超出其設(shè)計承載能力,再加上這些橋梁結(jié)構(gòu)已經(jīng)服役多年,力學(xué)性能顯著下降。橋梁結(jié)構(gòu)損傷日積月累,成為交通運輸發(fā)展的一個頑疾,輕則橋毀,重則人亡。因此,有必要對橋梁結(jié)構(gòu)進(jìn)行損傷識別,制定有效加固措施,避免安全事故發(fā)生。橋梁運營多年后會帶有損傷,而損傷會使橋梁結(jié)構(gòu)模態(tài)參數(shù)改變,進(jìn)而影響力學(xué)響應(yīng),為檢測結(jié)構(gòu)損傷,須知道模態(tài)參數(shù)和力學(xué)響應(yīng)的關(guān)系,從力學(xué)響應(yīng)中尋找影響其突變的模態(tài)參數(shù),對比損傷前后模態(tài)參數(shù)的改變,以此作為結(jié)構(gòu)損傷特征,進(jìn)行檢測和識別。近年來,小波變換迅速發(fā)展,在時-頻兩域分析信號均可局部化,受到各個領(lǐng)域研究者的青睞。本文借助小波對結(jié)構(gòu)響應(yīng)進(jìn)行小波變換,進(jìn)行損傷識別,主要做了以下工作:1.闡述了本文研究的背景和意義、橋梁結(jié)構(gòu)損傷識別常見方法及小波理論在橋梁結(jié)構(gòu)損傷檢測中的應(yīng)用。2.簡要介紹了小波理論(包括其發(fā)展過程),從傅立葉變換到小波變換過程及小波變換理論核心內(nèi)容。3.闡述基于小波異常信號檢測與識別原理,包括小波變換實質(zhì)、奇異點位置識別和Lipschitz指數(shù)計算,并介紹了選擇小波函數(shù)的原則和常用的幾種小波函數(shù)。4.介紹了簡支梁損傷力學(xué)模型,用有限元軟件模擬一個簡支梁,預(yù)設(shè)單損傷和多損傷,并且損傷程度不同,經(jīng)過分析后,得到各階位移模態(tài)振型,通過中心插值法得到各階曲率模態(tài),將各階曲率模態(tài)看作信號,在Matlab小波工具箱中選取bior6.8小波,對其進(jìn)行分析,得到多尺度下各階小波變換系數(shù),將損傷前后的小波系數(shù)作差,以此作為損傷指標(biāo),依據(jù)第3章小波異常信號檢測與識別原理,計算Lipschitz指數(shù),將其大小作為衡量結(jié)構(gòu)損傷嚴(yán)重性的一個重要指標(biāo)。5.連續(xù)梁橋損傷識別,用有限元軟件模擬某座變截面連續(xù)梁橋,采用第4章的方法進(jìn)行連續(xù)梁橋損傷識別,并確定其損傷位置和損傷程度。6.對本文工作了一個結(jié)論和展望。
[Abstract]:Prestressed reinforced concrete simply supported beam bridge and continuous beam bridge are widely used in municipal highway bridges in our country. Due to the increasing demand of traffic and transportation capacity, these bridges are often overloaded and far exceed their design bearing capacity. In addition, these bridge structures have been in service for many years, and their mechanical properties have declined significantly. The damage of bridge structure gradually becomes a stubborn disease of transportation development. Therefore, it is necessary to identify the damage of bridge structure and make effective reinforcement measures to avoid safety accidents. In order to detect the structural damage, it is necessary to know the relationship between the modal parameters and the mechanical response in order to detect the damage, which will cause damage after many years of operation, and the damage will change the modal parameters of the bridge structure, and then affect the mechanical response. The modal parameters which affect its mutation are found from the mechanical response, and the changes of modal parameters before and after damage are compared, which are regarded as structural damage characteristics to detect and identify. In recent years, wavelet transform has developed rapidly, and can be localized in both time and frequency domain, so it is favored by researchers in various fields. In this paper, the wavelet transform of structure response is used to identify the damage. The main work is as follows: 1. The background and significance of this paper, the common methods of damage identification of bridge structure and the application of wavelet theory in the damage detection of bridge structure are expounded. 2. This paper briefly introduces the wavelet theory (including its development process), from Fourier transform to wavelet transform and the core content of wavelet transform theory. The principle of detecting and recognizing abnormal signals based on wavelet is introduced, including the essence of wavelet transform, singular point position recognition and Lipschitz exponent calculation. The principle of selecting wavelet function and several kinds of wavelet functions are introduced. In this paper, the damage mechanics model of simply supported beam is introduced. A simple supported beam is simulated by finite element software. The single damage and multiple damage are preset and the degree of damage is different. After analysis, the modal modes of each order displacement are obtained. The curvature modes of each order are obtained by the central interpolation method. The curvature modes of each order are regarded as signals. The bior6.8 wavelet is selected in the Matlab wavelet toolbox, and the coefficients of each order wavelet transform are obtained by analyzing it. The wavelet coefficients before and after the damage are deviated. According to the principle of wavelet anomaly signal detection and recognition in Chapter 3, the Lipschitz exponent is calculated, and its size is regarded as an important index to evaluate the severity of structural damage. The damage identification of continuous beam bridge is simulated by finite element software. The method of chapter 4 is used to identify the damage of continuous beam bridge, and the damage location and damage degree are determined. A conclusion and prospect of this paper are given.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U446

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