型钢-混凝土结构界面的损伤监测试验研究

Experimental study on monitoring interface damage of steel-concrete composite structure

型钢-混凝土结构连接界面的损伤监测具有重要实际意义。本文提出一种基于压电智能材料的型钢-混凝土结构界面损伤主动传感监测方法。在型钢上翼缘下表面连接件附近粘贴6套锆钛酸铅(Lead Zirconate Titanate, PZT)压电陶瓷片作为发射应力波的驱动器,并在翼缘板内对应位置处布设7个智能骨料传感器以采集经由损伤界面传来的响应信号。通过依次松动型钢-混凝土结构试件中对称布置的四颗螺栓,模拟连接界面的损伤状况,再对上述损伤状况下响应信号进行时域、频域以及小波包能量的对比分析。由试验结果分析可知,时域信号幅值、频域信号幅值以及小波包能量幅值都随着损伤状况的加剧出现了明显的降低,这主要是由于螺栓松动导致型钢与混凝土实际接触面积的减小,阻挡了应力波的传播。试验结果表明基于压电陶瓷的主动传感监测方法能够有效地监测和评价型钢-混凝土结构界面的损伤状况。

Monitoring interface damage of steel-concrete composite structures becomes more and more important in applications. Here a piezoceramic-based active sensing monitoring method for interface damage detection of the composite structures is proposed. Six lead zirconate titanates (PZTs) patches bonded on the lower surface of the joist steel upper flange near the bolt joints are used as the actuators to generate stress waves. Seven smart aggregates(SAs), fabricated by sandwiching a shear type PZT patch between two protection marble pieces, are embedded at the corresponding positions in the concrete flange plate to collect response signals from the damaged interface. To simulate the interface damage, four bolt joints arranged symmetrically in the composite structure are loosened successively. The time-domain signal, frequency-domain signal and the wavelet packet energy are compared and analyzed under different damage conditions. According to the analysis of experimental results, the amplitudes of time-domain signal, frequency-domain signal and wavelet packet energy decrease obviously when the structure interface damage is enhanced. The reason mainly lies in the fact that the actual contact area between shape steel and concrete decreases due to the loosening of bolts, which blocks the propagation of stress waves. Experimental results demonstrate that the active sensing monitoring method based on PZT transducers can effectively monitor and estimate the damage status of steel-concrete interface.