23 Dynamic Testing on the New Ticino Bridge of the A4 Highway 189 Fig. 23.1 (a) Scheme of the cross section of the bridge deck and (b) the bridge under construction Fig. 23.2 Details of the FEM of the bridge—cross sections and friction bearings modeled with four springs criteria such as low aspect ratio, avoidance of small or large angles in elements and avoidance of small to large element transitions. The modes obtained from modal analysis are typically similar to a static wave with close frequency values. For instance, Modes 1, 2 and 3 are similar vertical modes, while 8, 9 and 10 are similar torsional modes. These mode shapes and frequencies will be compared to those derived from preliminary operational analysis in the next section. The frequencies and mode shapes are slightly different for the two travelling ways, due to the presence of the additional pedestrian way on the MI-TO side, but the same, very closely spaced, modes appear in both cases. In Table 23.1, the first 14 natural frequencies and mode shapes of the MI–TO way, identified by numerical linear modal analysis, are shown.
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