Damage Localization of Beam Bridges Using Quasi-Static Strain Influence Lines Based on the BOTDA Technique

Abstract

The diagnosis of damage in a bridge superstructure using quasi-static strain influence lines (ILs) is promising. However, it is challenging to accurately localize the damage in a bridge superstructure due to limited numbers of strain IL measurement points and inconsistencies between the loading conditions before and after damage. To address the above issues, the Brillouin optical time domain analysis (BOTDA) technique is first applied to bridge damage localization using quasi-static strain ILs, and the number of strain IL measurement points is substantially increased. Additionally, a damage localization index based on quasi-static strain ILs that is independent of differences in the loading conditions before and after damage is proposed to localize damage in the superstructure of a beam bridge. Finally, the effectiveness of the proposed method is demonstrated through both numerical analysis and measured data from a quasi-static test of a model bridge.

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

“…The main stream DFOS widely used in strain monitoring based on Brillouin Scattering technology are the BOTDR, BOTDA, and BOFDA [43]. They have been applied to the strain monitoring of various kinds of structures in many industries, such as high anchored pile wall in gravel [44], Bored Pile [45], Pile Foundation [46], Beam Bridges [47], similar material test model [48], steel rails [49], subsea Sensors 2020, 20, 1318 4 of 31 cables [50], geotechnical structures [51], River Levee Collapse, Concrete Structures and yacht [52], tunnel healthy [53], the state of underground copper mine [54], land subsidence [55], airplane structure health [56], and so on.…”

Damage Detection in Beam Bridges Using Quasi-static Displacement Influence Lines

“…Therefore, the weight of the loading vehicle is determined on a case-by-case basis in consideration of the real technical conditions of the bridge. It is recommended that, for an actual bridge [25], the reference weight of the loading vehicle should first be equal to the weight of one loading vehicle determined by using the design of a Suppose that the bridge is simply supported and composed of several beams in the transverse direction, as shown in Figure 1. Three sensors are placed on cross-section A, cross-section B and cross-section C on the side beam beneath the bridge (Beam #1) to measure the vertical displacement.…”

“…Therefore, the weight of the loading vehicle is determined on a case-by-case basis in consideration of the real technical conditions of the bridge. It is recommended that, for an actual bridge [25], the reference weight of the loading vehicle should first be equal to the weight of one loading vehicle determined by using the design of a transitional load test; then, this reference weight can be adjusted to the final load by evaluating the real structural conditions of the bridge.…”

“…However, the above loading condition is difficult to implement during actual load testing of a bridge. To address this issue, a method for identifying damage using the strain ILs based on the Brillouin optical time domain analysis (BOTDA) technique is proposed by the authors of this study [25]. Quasi-static strain ILs are applied to generate a damage location index that is independent of the difference between the weight of the loading vehicle before and after damage.…”

“…The displacement information helps determine if damage exists. In consideration of the above issues, on the basis of the previous method [25], an improved method is proposed to detect the damage of beam bridges using only a few quasi-static displacement ILs. While the reconstruction of the Hankel matrix of the damage feature is presented to establish the damage feature using a few quasi-static displacement ILs, the method used to obtain the metric for evaluating the damage feature is improved so that the efficiency of damage detection using quasi-static ILs is greatly increased.…”