Indirect Method for Measuring Bridge Frequencies: Numerical Simulation and Noise Treatment for Experiments
Date Issued
2012
Date
2012
Author(s)
Chao, Ting-Fu
Abstract
Bridge frequency is an essential dynamic parameter, which reflects the change in structural stiffness of the bridge. Since it is easier to capture the frequency in comparison with the mode shape and damping ratio, methods for measuring bridge frequencies have been well developed in the past. Traditionally, the bridge frequencies are analyzed from the dynamic response of the bridge, which was recorded via the vibration sensors directly mounted on the bridge. Such an approach has been referred to as the direct approach.
In recent years, another approach has been proposed to overcome the defects of the direct approach, it provides a more efficient and economical way for measuring the bridge frequencies. Such an approach was called the indirect approach.
The concept of the indirect approach is to mount the vibration sensor on a moving vehicle, and to capture the bridge frequencies indirectly from the response of vehicle recorded during its travel over the bridge. Due to its advantage in speed and movabilty, engineers are able to make safety assessment on the bridge of concern at a short time based on the bridge frequencies obtained by this approach.
The objective of this study is to explore further in the indirect approach by using the numerical simulation to evaluate the effects of road roughness and transient jump of wheels, as well as to enhance the applicability of the indirect approach by processing the signals recorded from three bridges with the Stochastic Subspace Identification technique.
Subjects
bridge frequencies
indirect approach for measuring the bridge frequencies
road surface roughness
transient jump of wheel
Singular Spectrum Analysis
Stochastic Subspace Identification technique
Field tests
Type
thesis
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