本文選題：橋梁結(jié)構(gòu) + 損傷識(shí)別��； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：橋梁結(jié)構(gòu)由于其結(jié)構(gòu)本身性能退化及外部因素的影響會(huì)發(fā)生損傷、裂紋等形式的破壞。結(jié)構(gòu)一旦發(fā)生破壞,將造成重大的人員傷亡,威脅社會(huì)的安定與國(guó)家的長(zhǎng)治久安。因此,防患于未然,為了避免重大橋梁事故的發(fā)生,對(duì)已有橋梁結(jié)構(gòu)進(jìn)行健康狀況監(jiān)測(cè),探索一種簡(jiǎn)便有效的檢測(cè)方法,便具有重要的學(xué)術(shù)價(jià)值及實(shí)用意義。本文以小波分析和分形維數(shù)為基本工具,以結(jié)構(gòu)的振動(dòng)信息為基礎(chǔ)進(jìn)行橋梁結(jié)構(gòu)損傷識(shí)別(主要進(jìn)行損傷定位),主要進(jìn)行了以下幾方面的研究:首先提出了一種基于分形理論與振型相結(jié)合的損傷定位方法;損傷的存在使結(jié)構(gòu)的振型曲線在損傷位置的不規(guī)則程度變大,而Katz分形維數(shù)可用來(lái)定量描述曲線的這種不規(guī)則程度,因此利用Katz滑動(dòng)窗沿振型曲線滑動(dòng),得到各測(cè)點(diǎn)的分形維數(shù),并將含裂紋簡(jiǎn)支梁與完好簡(jiǎn)支梁各測(cè)點(diǎn)分形維數(shù)相比較便可進(jìn)行損傷識(shí)別;并將分析裂紋處于結(jié)構(gòu)不同位置、裂紋相對(duì)深度的大小及裂紋條數(shù)對(duì)損傷定位效果的影響。其次引入小波分析的概念,并通過(guò)小波的多分辨率分析功能,對(duì)沖擊荷載作用下多階模態(tài)疊加振動(dòng)響應(yīng)進(jìn)行有效的分離,以其中識(shí)別效果最好的一階模態(tài)響應(yīng)為處理對(duì)象,定義相對(duì)小波能量分形維數(shù)差與一階加速度響應(yīng)分形維數(shù)差兩種損傷,并對(duì)損傷進(jìn)行定位,通過(guò)簡(jiǎn)支梁的數(shù)值模擬及實(shí)驗(yàn)進(jìn)行驗(yàn)證。最后通過(guò)結(jié)合小波能量與模態(tài)柔度曲率差都對(duì)損傷敏感的特性,提出一種相對(duì)小波包能量柔度曲率差損傷指標(biāo)來(lái)判斷損傷位置;并與僅基于相對(duì)小波包能量曲率差的方法進(jìn)行比較,通過(guò)連續(xù)梁的數(shù)值模擬及連續(xù)梁的試驗(yàn)驗(yàn)證說(shuō)明該方法的可行性。
[Abstract]:Because of the degradation of the structure itself and the influence of the external factors, the bridge structure will be damaged and damaged in the form of cracks. Once the structure is destroyed, it will cause heavy casualties and threaten the stability of the society and the long-term stability of the country. Therefore, in order to avoid the occurrence of major bridge accidents, it is of great academic value and practical significance to monitor the health status of existing bridge structures and to explore a simple and effective detection method. In this paper, wavelet analysis and fractal dimension are used as the basic tools. Based on the vibration information of the structure, the damage identification of bridge structure is carried out (the damage location is mainly carried out in the following aspects): firstly, a damage location method based on fractal theory and vibration mode is proposed; The existence of damage increases the degree of irregularity in the damage position of the structure, and the fractal dimension of Katz can be used to quantitatively describe the irregularity of the curve. Therefore, the Katz sliding window is used to slide along the mode curve. The fractal dimension of each measuring point is obtained, and the damage identification can be carried out by comparing the fractal dimension of simply supported beam with crack with that of intact simply supported beam, and the analysis crack is located in different position of structure. The influence of the relative depth of crack and the number of cracks on the effect of damage location. Secondly, the concept of wavelet analysis is introduced, and the multi-resolution analysis function of wavelet is used to effectively separate the multi-order modal superimposed vibration response under impact load, and the first-order modal response, which is the best one, is taken as the processing object. The relative wavelet energy fractal dimension difference and the first order acceleration response fractal dimension difference are defined, and the damage location is carried out, which is verified by the numerical simulation and experiment of the simply supported beam. Finally, by considering the sensitivity of wavelet energy and modal flexibility curvature difference to damage, a damage index of relative wavelet packet energy flexibility curvature difference is proposed to judge the damage location. Compared with the method based on relative wavelet packet energy curvature difference, the feasibility of this method is verified by numerical simulation of continuous beam and experiment of continuous beam.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U446

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