Experimental construction of mode shapes of a simply supported bridge by using dynamic responses extracted from a moving vehicle under impact excitation

Abstract

Constructing the mode shapes of a bridge has been an interesting research topic in recent years. A variety of theoretical methods for constructing mode shapes have already been developed. However, relatively few experimental studies have managed to identify accurate mode shapes of bridges by using the dynamic responses from a moving vehicle. Therefore, an experimental study was carried out for constructing the mode shapes of a simply supported model bridge by using the dynamic responses extracted from a model vehicle moving on the bridge. Moreover an additional impact exciter was installed on the model vehicle to help excite the model bridge, which could help to improve the accuracy of mode shapes identified. After collecting the vehicle responses from the moving model vehicle, a suitable band-pass filter was used to extract the component response associated with each natural frequency of the model bridge. The mode shape associated with the selected frequency could then be constructed based on Hilbert Transform. The effects of vehicle speed, vehicle parameters, etc. on the accuracy of results were also evaluated.