Civil Engineering Reference
In-Depth Information
2.5
Jogger Tests, Performance and Results
After each of the five Experimental Modal Test setups on the complete structure as described in Chap.
3
, a series of jogger
tests were performed. This was stretching the test time schedule to the max because the measurement chain sensitivity of 24
channels had to be adapted to the necessities and back. And the frontend software used in combination with the very slow
Windows 7 operating system is not really up-to-par to cope with such a problem in an efficient way. However, we survived,
loosing a lot of blood, sweat and tears (the outside temperature being some 30
Celsius). Figure
2.21
gives the jogger
instrumentation as used to making the jogger keep a step pace of f
¼
2.73 Hz (B2) and to getting rid of Doppler Effects.
Firstly, there is one thing we can learn from the deflection signals (derived through double integration of the acceleration
signals) and spectrum given in Fig.
2.22
: The bridge does not like an input with f
¼
2.73 Hz, because this is not its
Fig. 2.21
Jogger test instrumentation. The frequency generator transforming the electronic sinus wave to an acoustic impulse signal is not visible
Fig. 2.22
Time signal and PSD-spectrum, point 202 (0.33 L), vertical. Jogger running over the bridge and back
