【作者】 王斌；

【导师】 孙宗军；

【作者基本信息】 山东科技大学 ， 交通运输规划与管理， 2009， 硕士

【摘要】 桥梁是交通运输系统的重要组成部分,随着现代交通事业的飞速发展,对桥梁结构的安全性和使用要求越来越高。如果桥梁结构发生破坏,对国民经济、社会稳定和人民的生命财产产生重大影响。需要快速有效地识别出桥梁结构可能发生损伤部位和损伤程度,因此,对桥梁结构进行实时的健康检测、损伤识别是十分必要。本文首先介绍了小波分析的理论基础,小波分析是近十几年发展起来的数学理论,它被认为是傅立叶分析方法的突破性发展,是一种新的时-频两维分析方法。接着介绍了小波奇异性检测的原理,运用连续小波变换可以很好的对简支梁桥的损伤位置进行精确定位,通过小波系数模极大值和变换尺度得到的Lipschitz指数对损伤程度进行识别。利用Ansys软件建模模拟一简支梁桥结构发生不同损伤的情况,提取桥梁的振型模态,利用小波函数对基本振型进行多尺度变换,由小波系数模极大值识别出桥梁结构发生损伤的位置,根据小波系数模极大值的相对大小判断损伤的相对程度。通过模极大值的小波系数得到Lipschitz指数,用来描述损伤的程度。讨论了损伤程度大小、损伤位置、尺度大小、小波基的选择、振型阶数对识别损伤位置和程度的影响。讨论了轻微损伤时,以应变模态和曲率模态作为小波变换参数比以振型为参数的识别效果更好。建立实体桥梁模型,利用小波变换可以明显的发现桥梁损伤的位置。更多还原

【Abstract】 Bridge is one of the vital parts of the traffic and transportation system. With rapid development of the modern transportation, more and more requirements are taken out due to safety and utility of bridges. If a bridge loses its function, national economics, social stability, people’s lives will be affected. The bridge structure damaged position and extent need be identified quickly and efficiently, therefore, it is very necessary to set up a system to carry out real-time healthy detection, damage identification for a bridge.The paper is related to the basic theories. Wavelet analysis is a new mathematic method which has developed rapidly. It is regarded as a breakthrough of Fourier Analysis. It has strong analytical skills with time-frequency. then wavelet singularity theory is described, continuous wavelet transform can be used to detect exactly the damaged location in a damaged bean-bridge. And meanwhile continuous wavelet transform can be used to estimate the Lipschitz exponent, the magnitude of which can be used as an indicator of the damage extent.Finite element model is built by Ansys to simulate different damage situation of a simply supported bridge. The vibration mode shape is analyzed using continuous wavelet transform by wavelet on multiple scales. And the damage position and damage degree can be identified by the maximum of modulus of the wavelet coefficients and the Lipschitz exponent. In addition, some influencing factors are analyzed, such as the location of damage, damage degree,the size of scale, the type of mother wavelet and wavelet transform, the step of vibration mode shape. The Strain mode and the curvature mode are analyzed using continuous wavelet transform by wavelet, they have better results when we discuss minor damages. Established entity bridge model, location of damage can be found using wavelet transform.更多还原