19. System for monitoring soundness of railway bridges

As railway bridges age, there is a growing demand for low-cost maintenance procedures.

Until recently, the soundness of bridges was diagnosed using field measurements, impact vibration tests etc. Now, however they can be diagnosed effectively using monitoring methods that track their soundness. As such a monitoring system was developed comprising an acceleration sensor for measuring pier vibrations, and sensors to detect bearing point displacement between the piers and girders, powered by batteries charged using power generated from steel girder vibrations. In addition, a wireless transmission device was developed to add to this monitoring system to allow data to be collected remotely, without going on site (Figure 1).

It was deemed that for bridge piers, a monitoring system based on the structure’s natural frequency would be particularly efficient. Therefore, a new soundness diagnosis index for bridge piers was devised, drawn from sources closely correlated to the natural frequency of bridge piers, such as the power spectral area ratio of micro-tremors (ratio of total area to low frequency area) (Figure 2).

Confirmation was obtained that this index can be used for diagnosing the soundness of actual bridge piers over the long term (Figure 3).