【作者】 詹丽；

【导师】 李慧剑； 高柏峰；

【作者基本信息】 燕山大学 ， 结构工程， 2010， 硕士

【摘要】 连续梁结构是桥梁的一种常见形式,在工程中应用广泛。在风、地震荷载作用及自然环境侵蚀下,结构某些部位将产生损伤,结构的刚度、强度等力学性能随之降低,这种力学性能的降低直接影响到结构动力特性的变化。小波变换是一种时频域分析方法,具有多分辨率分析的特点,是奇异性信号分析的合适工具。本文基于国内外学者对结构损伤识别方法的研究,采用位移均方差作为损伤指标,并利用小波变换来实现结构损伤位置和损伤程度的识别。无论是现场测试还是数值分析,所采集到的动力响应信息是有限的。当对其进行小波变换时,各个分解量在其边界处一般都会出现Gibbs现象。通过比较处理有限区间信号边界问题的典型方法,文中提出了基于曲线拟合技术的信息拓展方法,并通过算例验证了该方法。针对无刚度变化的连续梁,利用信息拓展的方法,抑制Gibbs振荡现象影响,对连续梁结构进行损伤识别,将小波变换识别结构损伤信息的范围拓展到结构整体,特别是结构边界区域;对于多损伤的连续梁结构,由于受损伤之间以及自身支座的影响,结构损伤位置难以识别。为此,引入信息截断的方法,从而消除这些影响,并结合信息拓展方法对响应信息进行处理,完成损伤位置的准确识别。最后利用小波系数模极大值点处对应的Lipschitz指数来判断结构损伤的程度。对移动荷载作用下连续梁结构的位移均方差曲线进行连续小波变换,研究Lipschitz指数随损伤程度、损伤位置、损伤发生的数量、损伤之间的影响、荷载的大小、荷载速度的变化规律。更多还原

【Abstract】 The multisupported beam structure is a common form of bridge,and widely applied in engineering. Under the wind or earthquake loads, and natural environment erosion, some local structural damage appear and its mechanics character degradation of stiffness and strength. This degradation has the directly effect on the structure dynamic character. Wavelet transform is a analysis method both for time and frequency domain, and it adapted well to singularity analysis for its multi-resolution. Based on study of civil and abroad scholars to structural damage identification methods in this paper, standard deviation of acceleration used as damage index, and wavelet transform is used for identification of the site and degree of damage.Dynamic response information of collectting is limited, whether field test or numerical analysis. Each decomposition amount could generally appeared Gibbs phenomenon at its boundary while wavelet transform. After compared the typical methods by treating edge problem of the signal with limited time zone, method of information expansion based on curve fitting is proposed in the paper, and validated this method by numerical example.For the multisupported beam with uniform stiffness,the method of expanding the use of information and inhibit the effects of Gibbs oscillations, the multisupported beam structures for damage detection, wavelet transform to identify structural damage information of the range extends Dao whole structure, particularly the border region is a structure; for more multisupported beam damage, due to injury as well as between the impact of their bearing, structural damage location is difficult to identify. To this end, the introduction of information truncated methods to eliminate these effects and to develop methods of combining information on the response information to process, complete and accurate identification of damage location.Finally, the wavelet coefficients modulus maxima points corresponding Lipschitz index to determine the extent of structural damage. On the multisupported beam under moving load displacement of the structure of the continuous wavelet transform variance curve, with the damage of Lipschitz index of the degree of damage location, damage occurred in the number of injuries between the effects of load size, load speed variation.更多还原