Experimental and analytical modal analysis of a multiple-span motorway bridge

The paper presents the experimental and analytical modal analysis for an eleven-span continuous concrete deck bridge in New Zealand. Sine-sweep forced-vibration testing by rotating weight shakers was conducted to excite the bridge within the frequency band of interest. One of the most advanced time domain system identification techniques, i.e. the data-driven stochastic subspace identification, was used to extract the modal parameters of the bridge. Correlation analysis among the developed beam-element girder, shell-element girder models and experimental measurements was carried out in terms of natural frequencies and mode shapes, and a good agreement was achieved. This suggests that both developed numerical models have adequate accuracy from the point of view of engineering practise for precisely calculating dynamic response in different circumstances, such as earthquakes and traffic loading, as long as linear response range is considered