Application of the vehicle-bridge interaction theory to damage detection of bridges
Date Issued
2015
Date
2015
Author(s)
Chen, Chang-An
Abstract
It is an urgent matter to confirm the safety of brides after the occurrence of major disasters such as earthquakes and typhoons. The frequency of vibration is one of the important properties for bridges, as it can reflect the change in stiffness of the bridge. Compared with the modal shape and damping ratio, the frequency of a bridge can be measured in a relatively easy way. In the past half a century, techniques developed for the measurement of bridge frequencies are considered mature. Conventionally, to measure the bridge frequencies, we have to mount directly the sensors on the bridge and use the vibration response recorded by the sensors to identify the frequencies. Such an approach has been referred to as the direct approach. Starting from 2004, a new method for measurement of bridge frequencies, referred to as the indirect approach, has been proposed by Yang and co-workers aimed at overcoming the drawbacks of the direct approach, while offering advantages such as mobility and economy. With this approach, a test vehicle mounted with vibration sensors is allowed to pass the bridge of concern, and the response recorded of the vehicle during its passage is then used to extract the bridge frequencies. Due to its mobility, this approach is particularly suitable for measuring the bridge frequencies after the occurrence of a major natural disaster, which can offer an in-time reference for engineers to evaluate the safety of bridges. The objective of this thesis is to use the numerical approach to simulate the indirect measurement of bridge frequencies. First of all, we shall adopt the theory of vehicle-bridge interaction to study the indirect measurement of bridge frequencies for the case of smooth road surface. Next, we shall introduce the effect of road surface roughness and investigate the response of the test vehicle under various levels of roughness profiles. In addition, we shall consider the case of two test vehicles in connection, allow them to pass the bridge of concern, and then deduct the spectral response obtained for one vehicle from the other so as to eliminate the pollution effect of road surface roughness. Moreover, for various scenarios of damages, the transmissibility of a structure will be computed for identifying the damages in the bridge. Finally, concluding remarks will be drawn for the numerical examples presented in this thesis, while directions for possible future research will be highlighted.
Subjects
bridge
damage identification
frequency
indirect measurement approach
road surface roughness
test vehicle
vehicle-bridge interaction
transmissibility
Type
thesis
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