23 Dynamic Testing on the New Ticino Bridge of the A4 Highway 191 69.3 SA P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 SB 69.3 69.3 69.3 69.3 69.3 69.3 69.3 69 1175.4 69 69 69 69 69 69 69 69 Fig. 23.4 Investigated spans, dimensions in meters Fig. 23.5 Measurement grid: (a) locations and (b) channel numbers 23.4.1 Description of the Tests The measurement mesh and dimensions of investigated spans are shown in Figs. 23.4 and 23.5. The response of the bridge was measured at twenty measurement points in the vertical direction and seven in the transverse direction (Fig. 23.5). The sensors placement was based on the numerical model in order to get reliable results for the first mode shapes. As for the choice of the sensors for measuring the structural response, the accelerometers were piezo-electric sensors used for seismic applications. In fact, this type of sensors ensures excellent sensitivity to vibration and a large enough bandwidth even for low frequencies, granting a high signal to noise ratio even for very low frequencies. More in detail, with reference to the positions shown in Fig. 23.5, the patterns of accelerometer used were:
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