Impact of Road Profile when Detecting a Localised Damage from Bridge Acceleration Response to a Moving Vehicle

Previous work by the authors have shown that the acceleration response of a damaged beam subject to a constant moving load can be assumed to be made up of three components: 'dynamic', 'static' and 'damage'. Therefore, appropriate filtering of the acceleration signal can be used to highlight the ‘damage’ component and quantify its severity. This paper builds on these findings to examine if the same approach can be used to identify damage in the more realistic case of a bridge loaded by a sprung vehicle travelling on a road profile. The consideration of a road profile has the effect of exciting the vehicle modes of vibration which will corrupt the spectrum of bridge accelerations with road/vehicle frequencies. Some of these vehicle frequencies may be lower than the first frequency of the bridge and close to the frequency of the 'damage' component. In the latter, the vehicle frequencies are difficult to remove without also filtering part of the 'damage' component out. As a result, the approach is shown to perform best for low vehicle speeds.