Dynamic Measurements on the Amposta Suspension Bridge by Microwave Remote Sensing

The paper reports the results of dynamic testing a cable-suspended bridge, carried out using a radar interferometer. The investigated bridge crosses the Ebro River at Amposta, Spain and consists of two steel stiffening trusses and a series of equally spaced steel floor beams; the main span is supported by inclined stay cables and two series of 8 suspension cables. The dynamic test was performed in operational conditions, with the transceiver installed in different positions, in order to record the response of the deck and of all the arrays of inclined stay cables. Several vibration modes of the deck were successfully identified, using different output-only techniques, and a good agreement (in terms of both natural frequencies and mode shapes) was generally found between the different methods. Similarly, the application of classic spectral estimation to the data collected on the cables seems to provide accurate estimation of the cable frequencies.