Abstract
Damage detection of highway bridges is a significant part of structural heath monitoring. Conventional accelerometers or strain gauges utilized for damage detection have many shortcomings, especially their monitoring gauge length being too short, which would result in poor damage detection results. Under this circumstance, long-gauge FBG sensors as a novel optical sensor were developed to measure the macro-strain response of the structure. Based on this sensor, many derived damage detection methods were proposed. These methods exhibit various characteristics and have not been systematically compared. As a result, it is difficult to evaluate the state of the art and also leads to confusion for users to select. Therefore, a strict comparative study on three representative methods using long-gauge FBG was carried out. First, these methods’ theoretical backgrounds and formats were reformulated and unified for better comparison. Then, based on validated vehicle–bridge coupling simulation, these methods’ performances were tested through a series of parametric studies including various damage scenarios, vehicle types, speeds, road roughness and noise levels. The precision and reliability of three methods have been thoroughly studied and compared.
Highlights
Nowadays, in-service highway bridges always suffer from damage caused by external effects like normal traffic and material degradation
For the methods based on accelerometers, the core part is extracting modal information of a highway bridge like intrinsic frequencies and modal shapes from acceleration response through modal identification algorithms, such as frequency domain decomposition (FDD), stochastic subspace identification (SSI) [3,4,5]
After long-gauge fiber Bragg grating (FBG) was developed, many derived damage detection methods have been in which ε(x) represents the strain of point x, lAB represents the distance between A and B
Summary
In-service highway bridges always suffer from damage caused by external effects like normal traffic and material degradation. After being verified through numerical simulations and indoor experiments, these methods have been tested in actual bridges They were found to be insensitive to structural local damage. With current test technique, it is difficult to accurately obtain high order modal information Due to these reasons, the performance of accelerometer based methods is not satisfying in practical application. Conventional strain gauge has other shortcomings, like being fragile and sensitive to electromagnetic interference (EMI) [15,16] To solve these problems, distributed optical fiber (DOF) sensors such as Brillouin optical time domain reflectometer (BOTDR) were used for bridge damage detection [17].
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