本文選題：橋梁結構 + 損傷識別��； 參考：《天津大學》2014年碩士論文

【摘要】：橋梁結構由于其結構本身性能退化及外部因素的影響會發(fā)生損傷、裂紋等形式的破壞。結構一旦發(fā)生破壞,將造成重大的人員傷亡,威脅社會的安定與國家的長治久安。因此,防患于未然,為了避免重大橋梁事故的發(fā)生,對已有橋梁結構進行健康狀況監(jiān)測,探索一種簡便有效的檢測方法,便具有重要的學術價值及實用意義。本文以小波分析和分形維數(shù)為基本工具,以結構的振動信息為基礎進行橋梁結構損傷識別(主要進行損傷定位),主要進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合的損傷定位方法;損傷的存在使結構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)可用來定量描述曲線的這種不規(guī)則程度,因此利用Katz滑動窗沿振型曲線滑動,得到各測點的分形維數(shù),并將含裂紋簡支梁與完好簡支梁各測點分形維數(shù)相比較便可進行損傷識別;并將分析裂紋處于結構不同位置、裂紋相對深度的大小及裂紋條數(shù)對損傷定位效果的影響。其次引入小波分析的概念,并通過小波的多分辨率分析功能,對沖擊荷載作用下多階模態(tài)疊加振動響應進行有效的分離,以其中識別效果最好的一階模態(tài)響應為處理對象,定義相對小波能量分形維數(shù)差與一階加速度響應分形維數(shù)差兩種損傷,并對損傷進行定位,通過簡支梁的數(shù)值模擬及實驗進行驗證。最后通過結合小波能量與模態(tài)柔度曲率差都對損傷敏感的特性,提出一種相對小波包能量柔度曲率差損傷指標來判斷損傷位置;并與僅基于相對小波包能量曲率差的方法進行比較,通過連續(xù)梁的數(shù)值模擬及連續(xù)梁的試驗驗證說明該方法的可行性。
[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.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U446

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