Experiments on Large Structures - Dynamic Behavior of Concrete and Seismic Engineering - page 214

Figure 6.10. Instrumentation of the footbridge
Two different kinds of loading were used for the tests. In the first series of tests,
several pedestrians walked randomly across the footbridge, walking in an
unsynchronized way, in order that no vibration mode was favored. This was done in
order to extract the dynamic properties (frequencies and damping and vibration
modes) of the bridge under ambient vibrations. 120 s samples were recorded at 100
Hz for this part of the test.
Figure 6.11. Signals measured on the footbridge with different loading cases
The purpose of the second series of tests was to estimate the vibration level
under service loads. Pedestrian groups performed several “controlled” crossings, at
different speeds and with different numbers of pedestrians on the footbridge. Figure
6.11 illustrates the signals measured while pedestrians were crossing, and Table 6.1
gives the vertical acceleration maximum values measured on the bridge deck.