| Summary: | Vibration-based damage detection (VBDD) methods are structural health monitoring techniques that utilize changes to the dynamic characteristics of a structure (i.e. its natural frequencies, mode shapes, and damping properties) as indicators of damage. While conceptually simple, considerable research is still required before VBDD methods can be applied reliably to complex structures such as bridges. VBDD methods require reliable estimates of modal parameters (notably natural frequencies and mode shapes) in order to assess changes in the condition of a structure. This thesis presents the results of experimental and numerical studies investigating a number of issues related to the potential use of VBDD techniques in the structural health monitoring of bridges, the primary issue being the influence of the excitation source. Two bridges were investigated as part of this study. One is located on Provincial Highway No. 9 over the Red Deer River south of Hudson Bay, Saskatchewan. The other is located near the Town of Broadview, Saskatchewan, off Trans-Canada Highway No. 1, 150 km east of the City of Regina. Field tests and numerical simulations were conducted using different types of excitation to evaluate the quality of the modal properties (natural frequencies and mode shapes) calculated using these excitation types, and thus to evaluate the performance of VBDD techniques implemented using the resulting modal data. Field tests were conducted using different sources of dynamic excitation: ambient, traffic excitation, and impact excitation. The purpose of field testing was to study the characteristics and repeatability of the modal parameters derived using the different types of dynamic excitation, and to acquire data that could be used to update a FE model for further numerical simulation. A FE model of the Red Deer River bridge, calibrated to match the field measured dynamic properties, was subjected to different types of numerically simulated dynamic excitation with different noise (random variations) levels added to ...
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