Advances in intelligent continuous structural health monitoring applications of bridges

Bridges are an extremely important part of today's infrastructure. In addition to being exposed to severe environmental conditions, a continuing increase in high volume of vehicle traffic and heavy truck loads have led to a higher rate of deterioration in the performance of many old bridges in Canada. The current practice of bridge infrastructure management is mainly based on manual visual inspection, which can lead to subjective and at times unreliable results. Recently the topic of vibration based structural health monitoring has attracted considerable interest as a new technology which offers the possibility of obtaining more accurate and objective information with respect to the deterioration and damage condition of instrumented structures. A sophisticated continuous, real-time remote monitoring system has been developed and installed on the Confederation Bridge in Prince Edward Island in eastern Canada to determine its field vibration properties and behaviour, and the variabilities associated with them, which are essential for the development of reliable structural condition assessment and damage detection techniques for bridges in practical field applications. The vibration component of the monitoring system captures the ambient vibration responses of the bridge due to wind, traffic, ice, and earthquake loads. A robust software platform, Signal Processing Platform for Analysis of Structural Health (SPPLASH), has been developed in a previous phase of the project, encompassing the data processing, management, and analysis tools for the determination of the field vibration properties of the structure based on the stochastic subspace identification technique. A new, more efficient system identification module has been developed in the present study based on the newly developed polyreference least square complex frequency algorithm to enhance the real-time automatic data processing and analysis functionality of the monitoring software platform. The clean stabilization diagrams generated by the method allows for development of an automated pole selection procedure which reduces the subjectivity of the results and allows for reliable continuous monitoring and accurate assessment of the condition of a structure.