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Therefore, the proposed structural damage alarming indices ERVD under ambient vibrations are suitable for realtime damage alarming for longspan cablestayed bridges.


The analysis results of the measured responses further reveal that the damage alarming indices ERVD can sensitively reflect the influences of environmental temperature and typhoon loadings on the dynamic properties of Runyang Cablestayed Bridge.


The structural damage alarming method based on wavelet packet energy spectrum (WPES) for longspan cablestayed bridges is presented through combination of ambient vibration test and wavelet packet analysis.




 Threestage hierarchical identification strategy is used for the damage detection simulation of Kap Shui Mun Bridge. In the first stage, a novelty filtering technique in terms of the autoassociative neural network is proposed for damage alarming. The proposed method needs only a series of measured natural frequencies of the structure in intact and damaged states, and is inherently tolerant of measurement error and uncertainties in ambient conditions. The target in the second stage is to indentify... Threestage hierarchical identification strategy is used for the damage detection simulation of Kap Shui Mun Bridge. In the first stage, a novelty filtering technique in terms of the autoassociative neural network is proposed for damage alarming. The proposed method needs only a series of measured natural frequencies of the structure in intact and damaged states, and is inherently tolerant of measurement error and uncertainties in ambient conditions. The target in the second stage is to indentify the deck segment or section that contains damaged members. A normalized index vector derived from the mode shape curvature is presented for damage localization. The third stage is to indentify specific damaged members and damage extent by using a multilayer back propagation neural network. Only the members involved in the identified seg ment are considered in the network input. The so  called combined modal parameters are formulated for damage extent identification. The results show the strategy proposed is practical for largescale civil engineering structures.  基于高精度三维有限元模型以及模态灵敏度分析结果，对汲水门大桥损伤检测进行了数值模拟研究。该研究采用三阶段层次识别策略，首先确定损伤的发生，然后，确定损伤所在的区域，最后确定具体的损伤构件及损伤程度。所获得的汲水门大桥损伤识别模拟研究结果表明了本文所采用的策略与方法的可行性与实用价值。  The realtime structural damage alarming technology is studied based on wavelet packet analysis. The structural damage alarming is performed by analyzing structural vibrational signals due to finetime and frequency resolution of wavelet analysis. With respect to damage beams with open cracks, the energy spectrum of the wavelet packet is obtained with an environmental vibration signal by wavelet packet decomposition. The variation index and maximum index of energy spectrum based on the MonteCarlo... The realtime structural damage alarming technology is studied based on wavelet packet analysis. The structural damage alarming is performed by analyzing structural vibrational signals due to finetime and frequency resolution of wavelet analysis. With respect to damage beams with open cracks, the energy spectrum of the wavelet packet is obtained with an environmental vibration signal by wavelet packet decomposition. The variation index and maximum index of energy spectrum based on the MonteCarlo method are presented to judge the occurrence of beam cracks. Its advantage is that this new technique requires measured environmental signals without any analysis of the complete structure. The results obtained in the study show that a short crack can be detected effectively and efficiently, and numerical simulations verify the feasibility of the method.  研究了基于小波包分析的结构实时损伤报警技术 .利用小波分析优良的时频局部化特性对结构振动信号进行精细分析 ,从而能实时地实现结构损伤报警 .以简支梁裂缝为例 ,将环境振动信号采用小波包分解后得到小波包能量谱 ,采用基于Monte Carlo方法计算得到的能量谱极值指数和变异指数 2个指标作为简支梁裂缝损伤报警的判据 .该技术不需要对整体结构进行计算分析 ,只需要环境振动信号 .计算机数值模拟表明该技术能较为敏感地发现简支梁的微小损伤 ,从而证实了该技术的可行性 .  A systematic discussion is made on the theoretical basis and innate characters of the structural damage alarming based on wavelet packet energy spectrum with the multiscale decomposition theory of the dynamic structure. The state equation and observation equation under various analysis scales are derived using wavelet packet analysis together with the wavelet packet decomposition of system matrix and observation noise, which reveal that structural damage alarming using wavelet packet energy will... A systematic discussion is made on the theoretical basis and innate characters of the structural damage alarming based on wavelet packet energy spectrum with the multiscale decomposition theory of the dynamic structure. The state equation and observation equation under various analysis scales are derived using wavelet packet analysis together with the wavelet packet decomposition of system matrix and observation noise, which reveal that structural damage alarming using wavelet packet energy will have preferable damage sensitivity and noise robusticity. The effectiveness of structural damage alarming for longspan bridges is subjected to structural damage and observation noise; structural damage alarming parameters are constructed according to the wavelet packet decomposition of noise energy.  以润扬长江公路大桥为例,系统阐述了以小波包能量谱为基础的结构损伤预警方法的理论基础和本质特征。研究了以小波包分析为基础的结构动力系统的多尺度分解原理,推导了不同分析尺度上振动结构的状态方程和观测方程,并分析了结构系统矩阵和观测噪声的小波包分解特性,从理论上证明了基于小波包能量谱的结构损伤预警的敏感性和噪声鲁棒性。指出大跨桥梁结构损伤预警的有效性须考虑结构损伤和观测噪声的共同影响,并根据噪声能量的小波包分解特性提出了大跨桥梁结构损伤预警参数的计算方法。   << 更多相关文摘 
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