基于波动法的斜拉桥索力测试研究

Wave-Based Study for Cable Tension Measurement of Cable-Stayed Bridge

针对实际测量中正弦脉冲激励下产生的应力波含噪声大,走时时差难以分辨的问题,根据小波变换下有效信号和随机噪声在多尺度空间中模极大值不同的传播特性,采用近似对称的sym3小波对含噪信号图进行分解,每一层的小波分解系数用不同的软阈值处理.经过修正后的小波系数重构得到的信号图能够消去大部分噪声,清晰地反映入射波和反射波之间的时差.

The basic theory of cable tension measurement and its examination technology by the method of vibration wave are introduced in this paper. In practical measurement, it has found that stress wave excited by the sinusoid impulsion contains too much noise, so the time difference between two signals could hardly be discerned. According to the theory that the maximum modular values of wavelet transform signals and random noises have different spreading characteristics, wavelet sym3 which has approximately symmetric character is adopted to decompose the noise signal, and each wavelet transform coefficient is conducted by different soft threshold. The noise-extracted signal which is reconstructed by the revised wavelet coefficient could clearly reflect the time difference between incidence wave and reflection wave.