Sydney, July 31 - Monitoring changes in vibrations can detect hidden damage in bridges, said an Australian researcher.

Doctoral engineering researcher Henry Shih of Queensland University of Technology has developed a method to determine whether a bridge is damaged and even locate where the damage is in the structure.

The method used data obtained from the vibration monitoring of the bridge. The data collected is fed into a specially designed computer model which can identify any damage.

'Bridges vibrate from impacts and also from ambient factors such as normal traffic and wind,' he said. 'This method can be used to ensure the structure is safe, and if there is any damage detected, it can be fixed.

'In my research, I have tested the hypothesis by modelling the vibrations of small-scale steel bridges, both in their healthy and damaged states,' Shih said.

'The vibration data changed when the bridges were damaged and the computer model confirmed there was damage and indicated where the damage was located.

'It is best to have permanent instruments on bridges which continuously monitor changes in their vibrations,' he said.