基于瞬态冲击法的方钢管混凝土柱脱空检测试验

通过对有脱空缺陷的方钢管混凝土柱试件进行瞬态冲击作用下的检测试验,提出了根据振动信号频率变化、频谱峰值和WVD时频分布中频率的时间连续性等特征来进行脱空检测的新方法。基于WVD时频分布特性,提出了使用平均频率作为脱空判别指标。结果表明：当方钢管混凝土柱存在脱空,振动信号的平均频率发生明显降低,频谱图中频率成分简单,归一化频谱峰值高,在WVD时频分布三维图上呈现沿时间轴连续的偏平峰。说明该方法对检测方钢管混凝土柱脱空具有一定的有效性。

Experiment on Void Detection of Concrete-filled Square Tubular Column by Transient Impulse

A specimen of concrete-filled square tubular column with typical void defects is employed under transient impulse in the experiment. And a new method to detect the void is presented, which works according to the changes of frequency, the peak in frequency domain graph and the time continuity of frequency in WVD time-frequency distribution graph of vibration signal. The mean frequency based on the characteristic of WVD time-frequency distribution is proposed to judge void. The results show that the mean frequency of vibration signal reduces obviously, the frequency components are simple, the peak of normalized spectrum is high, continuous partial flat peak appears in three dimensional graph of WVD time-frequency distribution, when the void is present in the square concrete-filled tubular column, which verified the validity of the method to detect the void in square concrete-filled tubular column.