Development of an automated structural health monitoring system based on wireless sensor network for civil structures

Generally, Structural Health Monitoring (SHM) is used to identify damage and deterioration in civil structures during their regular lifetime as well as after earthquakes. A complete SHM system incorporates different components, such as sensing system, data management, data transmission, and data analysis for reliable decision-making purposes. During this research, a new vibration-based SHM system has been developed for condition assessment of large-scale civil structures. This structural health monitoring system consists of three significant components; a new wireless smart sensor network, a new MATLAB-based data management and data analysis platform compatible with the sensor network, and a new vibration-based nonlinearity identification technique for early damage identification purposes. The wireless smart sensor network has been designed to meet the requirements for low-amplitude ambient vibration measurement and sudden event monitoring of civil structures. The designed wireless smart sensor network can record both ambient and earthquake-induced vibrations from structures using two periodic and event-triggered sampling modes. A data management and data analysis toolbox has been also developed in MATLAB Graphical User Interface Layout Toolbox. Various time-domain and frequency-domain system identification techniques have been implemented into the toolbox to extract modal parameters from the vibration measurements. In addition, a vibration-based nonlinearity identification technique has been proposed to identify nonlinearities in a dynamic system. This technique combines vibration measurements with Autoregressive Moving Average with eXogenous inputs (ARMAX) model and Fuzzy C-means clustering (FCM) algorithm to categorise the linear and nonlinear behaviours of a structure, when it is subjected to various levels of earthquake excitation. To verify the reliability of different components of the developed SHM system, a series of shaking table tests was conducted on a steel truss bridge model at AUT structural laboratory. In addition, one span of a full-scale bridge, Newmarket viaduct located in Auckland, was instrumented using the developed wireless-based SHM system to investigate the system performance in an outdoor environment. The results obtained from the laboratory and field experiments showed that the developed vibration-based SHM system has a reliable performance in terms of hardware and software for condition monitoring of large-scale structures.