Dynamic Testing of a Full Scale Highway Truss: Vertical Electrodynamic White Noise Shaker Excitation

The truss was excited in the vertical direction with band-limited white noise to simulate ambient excitation in the field. The generated white noise, amplified using an amplifier is imposed on the truss using the electro-dynamic shaker (VG-100 from Vibration Test Systems). In all of the tests the shaker location was constant. For each of the test configurations, data was collected for multiple repetetions of the same shaker excitations. The truss was subject to band limited white noise of 0-200 Hz. In six of the tests, only a single direction (X, Y or Z) and either front of back panel were instrumented with 23 sensors. The seventh test was performed with the 18 sensors attached only on the lower chords front chord at six location in all 3 directions. Hence, data from this test was used to stitch together the other six tests to obtain complete 3 dimensional modal properties of the truss.The deployment of the sensors on the truss for each test is shown. In each test, the first channel was used to measure the input force excitation; modal hammer force or force transducer measurement located at the shaker and the other 23 channels were used to measure output acceleration at the nodes of the structure. Data was collected for 320 seconds at sampling frequencies of 512 Hz for the various sensor configurations. REFERENCE: Documents/Configuration file.doc for full information of test setup, data and damage cases