4.2 Measurement Description The measurement campaign was carried out by the Austrian company VCE and the University of Tokyo [10]. For vibration measurement a BRIMOS measurement system containing a permanent sensor grid was used. The grid consisted out of 15 sensor locations on the bridge deck, see Figure 2, in each location three sensors for measurement in the bridge decks vertical, longitudinal and transversal direction. All in all, for vibration measurement 45 acceleration sensors were applied. Additionally, for verification of the static response of the structure to the damaging, the vertical displacement of the bridge deck was measured in three characteristic locations. Fig. 2 Bridge deck with sensor grid for vibration measurement, on each location acceleration was measured in three directions [10]. The measurement took place with a sampling frequency of 500 Hz. All values were recorded permanently and stored in files with 165000 data points each. During the three days measurement campaign 714 data files each containing 48 channels were produced. The damage test took place between the 10 and 13 December 2008. Because of the time in year and because of clouds the variation of the bridge temperature over the whole period of the test was minimal. During the test the highway beneath the bridge was open in one direction. Therefore dynamic excitations from moving trucks can be found in the signals. The second direction was closed for traffic because of construction work which in addition took place near the bridge. Perturbation of the measurement signals by the undergoing road construction work cannot be ruled out. 4.3 Damage Description Prior to the demolition of the bridge a destructive damage test for measuring and investigating the structural behavior during damaging processes could be arranged and carried out. The campaign was planed and organized by VCE [10]. Two major damage scenarios were artificially induced. First, a significant damage on one of the four columns was reproduced by cutting through the column on its Confidence Intervals of Modal Parameters during Progressive Damage Test 243
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