Hybrid Piezo-Based Wireless Sensor Networks for Civil Structural Health Monitoring

Wireless sensor network technology has been introduced to civil structural health monitoring (SHM) systems to replace wired monitoring systems since it promises easy and flexible installation, low system cost and increased robustness. Piezo-based structural health monitoring systems have the advantages of low system cost and reliable output. Smart aggregates, which are pre-cast concrete blocks with embedded piezoceramic materials, can be used to perform SHM and impact detection tasks on concrete civil structures. The Smart aggregate (SA) based wireless SHM system utilizes the active sensing property of PZTs to realize SHM, while the passive sensing function is used to realize impact detection. In active sensing, one of the SAs is used to generate vibrations at a specific frequency range while another captures the vibration signal for analysis. Previous SA-based wireless sensor networks could be changed once the roles of the actuator (signal generator) and the sensor (signal receiver) are established during construction. To allow interchangeability between the roles of actuators and sensors, a hybrid SA-based WSN system for the SHM was designed and developed, which will be described in the paper. In the hybrid SA-based SHM system, nodes can be dynamically configured in software to take on the role of either sensor or actuator. This function can be utilized to optimize the active sensing strategy. Experimental results indicate that the designed hybrid system can dynamically configure the SA-based WSN system to realize the SHM function.