Experimental Study and Improvement on Indirect Method for Measuring the Bridge Frequencies
Date Issued
2015
Date
2015
Author(s)
Wu, Kuang-Fu
Abstract
Bridge frequency is the key parameter commonly used for detecting the integrity of bridges. Nowadays, two approaches can be used for measuring the bridge frequencies, i.e., the direct approach and indirect approach. With the direct approach, the dynamic properties of the bridge, such as frequencies and mode shapers, are obtained from the bridge response measured by the vibration sensors directly mounted on the bridge. In contrast, using the indirect approach, the dynamic properties of the bridge are extracted indirectly from the response of an instrumented test vehicle recorded during its passage over the bridge. The direct approach has been developed for many decades and is considered a mature technique. With proper arrangement of vibration sensors on a bridge, the frequencies and mode shapes of the bridge can be measured with no difficulty. The indirect approach was firstly proposed in 2004 by Yang and co-workers. It has been demonstrated to be capable of extracting the bridge frequencies both theoretically and experimentally. The purpose of this thesis is to study the effect of various test vehicles on the measurement results via the on-site test. The parameters considered include the type of tires, weight and moving speed of the test car, and so on. Based the test results achieved, it is concluded that the dynamic properties of the test vehicle are crucial to the successful extraction of bridge frequencies using the indirect approach. At the end, some conclusions based on the lab and field tests will be drawn, including particularly the basic rules for design of test vehicles. All these should prove useful to the future design of test vehicles, field tests, and related studies on the indirect approach.
Subjects
bridge
frequency
indirect measurement
on-site test
test vehicle
Type
thesis
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