应用声发射技术的钢筋与混凝土粘结滑移特性研究

Study of the Bond-Slip Behavior between Rebar and Concrete Based on Acoustic Emission Technology

为研究钢筋与混凝土间的粘结滑移特性,分别对不同粘结长度的钢筋混凝土试件进行了拉拔试验,同时对粘结长度相同而钢筋外形不同的试件进行了比较试验。利用声发射技术采集相应波形信号,并对采集信号进行了小波去噪和Gabor小波时频分析。结果显示,各试件受力全过程均可分为完全粘结、局部脱粘、非线性滑移及残余粘结四个阶段;不同粘结长度下的粘结滑移特性有所不同,其AE能量分布亦可反应该特性的变化;而钢筋外形不同的试件其粘结滑移特性有较大的区别,但不同试件在同一受力阶段,其声发射信号的时频特性基本相同。该研究同时得到了对应于构件宏观损伤和失效两个预警信号的声发射特性。

In order to study the bond-slip characteristics between rebar and concrete, pull-out experiment was carried out for reinforced concrete specimens with different bond length, meanwhile, pull-out comparative experiment for specimens with the same bond length but different shapes of embedding reinforcing steel bar was also carried out. Corresponding waveform signals were collected by using acoustic emission technology, and then wavelet denoising and Gabor wavelet time-frequency analysis were carried out for the acquired signals. Results show that whole loading progress of all specimens may be divided into four stages： fully bonding, local de-bonding, nonlinear sliding and residual bonding, respectively. The bond-slip characteristics are different due to specimen＇ s bond length. The AE energy distribution also reflects these properties. Whereas the shape difference of embedding reinforcing steel bar has a great influence on bond-slip characteristics. However, the time-frequency characteristics of AE signals collected at the same stages for different specimens are essentially similar. Characteristics of AE warning signals corresponding with macroscopic damages and failures of component are also obtained through this experiment.