 |
| Case Studies in Engineering Failure Analysis |
Vibration measurement-based simple technique for damage detection of truss bridges: A case study
ABSTRACT
The bridges experience increasing traffic volume and weight, deteriorating of components and large number of stress cycles. Therefore, assessment of the current condition of steel railway bridges becomes necessary.
Most of the commonly available approaches for structural health monitoring are based on visual inspection and non-destructive testing methods. The visual inspection is unreliable as those depend on uncertainty behind inspectors and their experience. Also, the non-destructive testing methods are found to be expensive.
Therefore, recent researches have noticed that dynamic modal parameters or vibration measurement-based structural health monitoring methods are economical and may also provide more realistic predictions to damage state of civil infrastructure.
Therefore this paper proposes a simple technique to locate the damage region of railway truss bridges based on measured modal parameters. The technique is discussed with a case study. Initially paper describes the details of considered railway bridge.
Then observations of visual inspection, material testing and in situ load testing are discussed under separate sections. Development of validated finite element model of the considered bridge is comprehensively discussed. Hence, variations of modal parameters versus position of the damage are plotted.
These plots are considered as the main reference for locating the damage of the railway bridge in future periodical inspection by comparing the measured corresponding modal parameters. Finally the procedure of periodical vibration measure- ment and damage locating technique are clearly illustrated.
Introduction
Most of railway bridges in the world are near the end of their design lives and many of them exceeds 100 years of age. Replacement of all these at once will be extremely expensive and practically impossible as there are large number of old bridges.
As a result, in the past two decades, a significant amount of effort has been directed toward the development of structural health monitoring and non-destructive assessment methods to maintain these bridges more efficiently.
Structural appraisal has been receiving more attention from bridge engineers due to recent failures in bridges in both developed and developing countries such as collapse of the Inter-state 35 W bridge in Minneapolis, Minnesota in July 2007; the Hoan bridge failure in Milwau-kee, Wisconsin in 2000; partially collapse of Cosen bridge in Latchford, Canada in 2003 and etc.
The detailed inspections of steel truss bridges in the word revealed damages such as cracks and fractures,severe deterioration due to corrosion of members, some of which already reached a complete loss of the cross section of the member Some of these damages are located in the regions, where it is difficult to access for visual inspections.
Mau donasi lewat mana?
Donate with PaypalGopay-