本文選題：橋梁 + 損傷識別　； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：橋梁結(jié)構(gòu)作為交通基礎(chǔ)設(shè)施中的重要樞紐，一旦出現(xiàn)問題將嚴(yán)重影響交通系統(tǒng)的正常運(yùn)行。橋梁在使用期間不斷受到各種荷載的作用，隨著服役時間的增長結(jié)構(gòu)內(nèi)部會出現(xiàn)損傷積累情況，若長期對此置之不理不予進(jìn)行及時維護(hù)必將導(dǎo)致惡劣事故發(fā)生。因此，如何有效識別橋梁結(jié)構(gòu)的早期損傷成為橋梁健康監(jiān)測領(lǐng)域的重要研究方向�，F(xiàn)有的研究手段多通過構(gòu)造反映結(jié)構(gòu)系統(tǒng)狀態(tài)的損傷指標(biāo)來識別損傷。本文基于小波包能量提出了一種新的橋梁損傷識別指標(biāo)及其損傷識別分析方法，并通過簡支梁數(shù)值仿真與斜拉橋模型試驗對其進(jìn)行了驗證，具體工作如下： 1、通過對已有損傷識別方法與小波分析理論的總結(jié)，定義了一種新的基于小波包能量的損傷識別指標(biāo)（Damage Detection Index，簡稱DDI），該指標(biāo)由小波包能量變化率平方和開方而來，同時給出了基于該指標(biāo)的損傷識別方法，并通過Matlab編程予以實(shí)現(xiàn)。實(shí)際應(yīng)用中利用小波包對環(huán)境激勵下的橋梁結(jié)構(gòu)加速度響應(yīng)信號進(jìn)行分析，根據(jù)小波包頻帶能量計算損傷指標(biāo)，利用損傷指標(biāo)的峰值進(jìn)行損傷識別。 2、利用簡支梁模型進(jìn)行數(shù)值仿真研究了DDI損傷指標(biāo)的識別能力。對模型施加隨機(jī)白噪聲荷載模擬環(huán)境激勵，并設(shè)定多種損傷工況、損傷程度與噪聲水平。分析表明損傷指標(biāo)對于不同工況、不同程度的損傷均能有效識別，，且損傷識別效果受到損傷程度與噪聲水平的雙重影響。 3、利用斜拉橋模型對損傷指標(biāo)的損傷識別效果進(jìn)行了驗證。對模型設(shè)定單一損傷與雙損傷兩種損傷工況，首先通過對斜拉橋數(shù)值模擬得到加速度響應(yīng)信號，據(jù)此對損傷識別效果進(jìn)行初步觀察；然后通過試驗測試得到不同工況下斜拉橋的加速度響應(yīng)信號，經(jīng)小波包分析得到損傷指標(biāo)，結(jié)果證明本文所提出的基于DDI損傷指標(biāo)識別方法有效可行。
[Abstract]:As an important hub of traffic infrastructure, bridge structure will seriously affect the normal operation of traffic system once problems occur. The bridge is continuously subjected to various loads during the service period. With the increase of service time there will be damage accumulation in the structure. If it is ignored for a long time and maintenance is not carried out in time it will lead to bad accidents. Therefore, how to effectively identify the early damage of bridge structure has become an important research direction in the field of bridge health monitoring. Most of the existing research methods identify damage by constructing damage indexes that reflect the state of the structure system. In this paper, based on wavelet packet energy, a new damage identification index and its damage identification method are proposed, and verified by numerical simulation of simply supported beam and model test of cable-stayed bridge. The concrete work is as follows: 1. By summarizing the existing damage identification methods and wavelet analysis theory, a new damage identification index based on wavelet packet energy, called damage Detection Index, is defined, which is derived from the square sum of wavelet packet energy change rate. At the same time, the damage identification method based on this index is given and realized by Matlab programming. In practical application, the acceleration response signal of bridge structure under environmental excitation is analyzed by using wavelet packet, damage index is calculated according to the band energy of wavelet packet, and damage identification is carried out by using the peak value of damage index. 2. The identification ability of DDI damage index is studied by numerical simulation with simply supported beam model. Random white noise load is applied to the model to simulate the environmental excitation, and a variety of damage conditions, damage degree and noise level are set. The analysis shows that the damage index can be effectively identified under different working conditions, and the damage recognition effect is affected by the degree of damage and the level of noise. 3. The damage identification effect of the damage index is verified by the cable-stayed bridge model. The single and double damage modes are set for the model. Firstly, the acceleration response signal is obtained by numerical simulation of the cable-stayed bridge, and the effect of damage identification is preliminarily observed. Then the acceleration response signals of cable-stayed bridge under different working conditions are obtained by test and the damage index is obtained by wavelet packet analysis. The results show that the method proposed in this paper based on DDI damage index is effective and feasible.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U446

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