Condition Monitoring of Masonry Arch Bridges using Acoustic Emission Techniques

40% of European railway bridges are masonry, 60% of which are over 100 years old and are still carrying traffic loading. The weight and density of traffic has increased substantially over the last century and bridge owners have the continuous responsibility to ensure safe working condition of their bridges. The condition assessment of masonry bridges generally relies on visual observation and there are limited number of techniques that provide insight into the actual condition of the masonry structure. There is an increasing need for techniques to help determine the bridge condition and predict their life expectancy. The acoustic emission technique has been applied to a series of masonry arch bridges in laboratory and in field to investigate its applicability for routine bridge assessment. The technique has shown to be able to identify damaged regions in the arch barrel, detect crack propagation and warn of residual damage occurring to the arch. It is also able, for the first time, to record the period of damage propagation which can allow sufficient time to remove critical loading and avoid crucial damage. The acoustic emission technique is simple and easy to use and has shown great potentials for assessment and monitoring of masonry arch bridges in the traffic network.