Abstract:
In this study, an experimental investigation was conducted on the changes to structural dynamic
behaviour due to loss of section of a laboratory timber bridge. The fabricated timber bridge initially
served as a benchmark to establish the dynamic characteristics of an undamaged bridge structure using
Experimental Modal Analysis (EMA). Several damage scenarios were subsequently introduced on one
of its girders to simulate damaged timber bridges. The modal tests/analysis were performed for each
damage scenario, by which the extracted modal parameters were compared against that of the
benchmark. The test results confirm that the detectable dynamic changes in terms of frequency
response function (FRF), natural frequency and mode shape due to different damage scenarios are
highly dependent on both ambient humidity and severity of damage. The investigation shows that
although the damage can reflect detectable dynamic changes of the bridge, without decoupling the
influence of humidity, employing damage identification methods may produce false identification
results. This investigation provides further insight into current available damage identification
algorithms with a view to establish new damage identification techniques for timber bridges.
