基于小波包能量谱的西安钟楼木结构的损伤识别

Damaged identification of Xi’an bell tower wood structures based on wavelet packet energy spectrum

应用小波包能量谱对环道行驶地面交通下的西安钟楼木框架结构进行损伤识别分析,构建了能量比偏差和能量比方差两个损伤识别敏感性指标。从小波函数的选择、小波包分解层次的选择、损伤敏感性和噪声的影响方面进行了分析研究。结果表明:两个指标都能有效地发现钟楼木框架结构的损伤,随着损伤程度增加,损伤识别越明显;在损伤初期,能量比偏差识别效果优于能量比方差,随着损伤的积累,能量比方差损伤敏感性优于能量比偏差;两个指标对不同损伤区域和损伤构件的损伤敏感性不同;在信噪比SNR≥40dB时,两指标都能准确地识别钟楼木结构的损伤,提高信噪比,两指标的敏感性增强,具有一定的抗噪声干扰能力,可为环境激励下古建筑木结构损伤识别的研究提供理论依据。

The damage identification of Xi’an bell tower wood frame structures is studied under ground transportation exciting of Xi’an bell tower’s ring,the damage detection indexes(energy ratio deviation and energy ratio variance)of Xi’an bell tower wood frame structures under ground transportation exciting are established with wavelet packet energy spectrum,from the selection of wavelet function and wavelet packet decomposition level and the damage sensitivity and the influence of noise.It shows that two indexes can effectively reflect damage of Xi’an bell tower wood frame structures,when the damage degree increases,the damage is more obvious.The energy ratio deviation is better than the energy ratio variance in the early damage,with the accumulation of damage the energy ratio variance is better than the energy ratio deviation,two indexes have different sensitivity to different damage areas and damage components.When SNR is 40 d B or bigger than 40 d B,two indexes can accurately identify damage of Xi’an bell tower wood frame structures.With the SNR improving,two index sensitivities gradually increase and have a certain capability to resist noise,it provides theoretical basis for damage detection of ancient wood structure under environment excitation.