| A system identification analysis of the three-span, Z24 bridge in Switzerland was performed to determine the dynamic characteristics of this bridge. The data used for this analysis were from tests performed on this bridge by researchers from the Katholieke Universitat Leuven. The natural frequencies, mode shapes, and damping values for this bridge were extracted from the field test data for both ambient and forced vibrations. The forced vibration data were run through a Fourier analysis and the modal parameters were picked off plots in the frequency domain. For the ambient excitation, the Frequency Domain Decomposition method was used to extract the dynamic characteristics from the data. The correlation between the natural frequencies determined from both types of excitation is quite good. The first five mode shapes produced by the two methods also showed good consistency. The damping values that were generated had quite a large variance between the two methods. |
