基于多通道卡尔曼滤波方法的砖砌体墙基本频率识别

Basic frequency identification for brick masonry walls based on multi-channel Kalman filtering

基本频率是评定砖砌体墙安全性的重要指标。为在识别砖砌体墙的基本频率时有效降低噪声干扰,设计了多通道的动力测试方案,并将卡尔曼滤波与奇异值分解相结合进行降噪处理。首先,通过伪静力试验获取砖砌体墙不同的损伤状态,并在环境激励下获取墙体在对应损伤状态下多个位置的加速度响应记录。然后,分别针对单一位置的加速度响应记录,采用KF方法引入墙体的物理参数进行降噪处理,进而识别墙体的基本频率。最后,采用奇异值分解综合利用所有降噪处理后的加速度响应记录,再识别墙体的基本频率。识别结果符合基本频率因损伤而降低的规律,能定量表示降低砂浆强度、增加开洞率和增加高宽比时基本频率的变化以及墙体损伤发展的过程。研究表明:采用卡尔曼滤波方法能够利用对墙体物理参数的合理先验判断有效降低噪声影响,较准确识别墙体的基本频率;在此基础上,结合奇异值分解能够综合利用多个加速度响应记录中的有用信息,提高基本频率的识别效果。

Basic frequency is an important index for safety assessment of brick masonry walls.To effectively reduce the interference of noise in basic frequency identification for the walls,a multichannel dynamic testing scheme was designed,and the Kalman filtering(KF)was combined with the singular value decomposition(SVD)to denoise.First,different damage states on brick masonry walls were imposed by pseudo-static tests,and then the acceleration responses at different parts of the damaged walls were recorded under ambient excitations.As the next step,the KF method that introduced the walls’physical parameters was used to denoise for each of the acceleration record.The walls’basic frequency was identified by using each denoised acceleration record separately.Finally,all the denoised acceleration records were combined by SVD,and the walls’basic frequency was identified again.The identified basic frequencies decrease along with the increase of damage severity.The identification results quantitatively relate the change of basic frequency to the decrease of mortar strength,the increase of the opening rate,and the increase of the aspect ratio,and they quantitatively reveal the damage process of the walls.The research shows that the KF can use reasonable prior judgment about the walls’physical parameters to effectively denoise and then accurately identify the walls’basic frequency.The identification results can be further improved by combining useful information in multiple acceleration records through SVD.