Instrumentation of a wireless transmission system for health monitoring of large infrastructures

Structural health monitoring and damage detection have been of great concern in the design, operation, maintenance, and repair of many civil structures. In order to monitor the health of large infrastructures such as highways, bridges, buildings, and dams, the outputs from various kinds of sensors, which are positioned at different places of civil structures, should be collected simultaneously and/or sequentially. However, the placement of sensors and wire connection is time-consuming and costly. Furthermore, the wires are easily damaged during the placement operation or in-service. In this paper, a wireless health monitoring system of civil structures is proposed. A novel wireless signal retrieval system, which is suitable to transmit wirelessly the response signal of large civil structures is developed. Special attention is paid to the low frequency response characteristics of the wireless transmitters/receivers due to the following two reasons: the dynamic response frequencies of civil structures are very low; the commercially available transmitter/receiver pairs have poor low frequency response characteristics near 0 Hz. The principles, feasibility, and configuration of the wireless monitoring system for the health monitoring of civil structures are investigated. Also a performance test experiment is done in the laboratory. The results show that the proposed monitoring method and the developed system are suitable for the in-situ and in-service health monitoring of large infrastructures wirelessly.