Damage Identification Method of Box Girder Bridges Based on Distributed Long-Gauge Strain Influence Line under Moving Load

Jing Yang,Peng Hou,Ning Yang,Caiqian Yang,Kefeng Li

doi:10.3390/s21030915

Jing Yang, Peng Hou + Show 3 more

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https://doi.org/10.3390/s21030915

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Abstract

A new method was proposed for the damage identification of box girder bridges under moving load, wherein the difference of strain influence line (DSIL) was taken as an index to represent the long-gauge strain difference before and after damage. The damage identification theory based on long-gauge strain influence lines was derived for box girder bridges with shear lag effect under consideration, and a regularized index DSIL was proposed for the quantitative identifications of damage location and extent. A series of experiments were carried out to study the influences of speed, vehicle type, and vehicle weight on the damage identification, and the experimental data were obtained by long-gauge fiber Bragg grating strain sensors. Moreover, numerical simulations were performed to confirm the method. The experimental and numerical results show that the method can locate the damage accurately, and quantitatively identify the damage extent under different working conditions. The experimental damage extent is generally slightly higher than the theoretical, with an average identification error smaller than 5%. Additionally, the relative error of damage extent is smaller than 3% under different working conditions. Thus, the effectiveness of this method was verified.

Highlights

As important transportation infrastructure, bridges occupy an important position in national economic development
It is of great significance to study and develop a structural damage identification and warning method suitable for box girder bridges in order to detect their early structural damage and evaluate the service state and safety of the box girder bridges, which is in favor of a reasonable maintenance and management
The difference of strain influence line (DSIL) values of each sensor under different working conditions can be obtained through inputting the long-gauge strain history curve into the method proposed in this paper

Summary

Introduction

Bridges occupy an important position in national economic development. Concrete box girder bridges are widely used on mediumand long-span bridges due to their unique cross-sectional form and usage characteristics They are affected by traffic load, overload, environmental erosion, earthquakes, and typhoons in daily operation, which will inevitably lead to structural damage. FDS-based methods mainly use the dynamic characteristics of the structure, such as natural frequency, mode, etc., to identify the damage and parameters of the structure, and to evaluate its working state and practical life; extensive literature reviews on FDS-based methods have been conducted [7,8,9,10,11] This method is not sensitive to local structural damage in practical application, which leads to the deviation of identification. It is greatly prone to external load, which obstruct its development [12,13,14]

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Results

Conclusion