Structural health monitoring of a steel stringer bridge with area sensing

Abstract

The Federal Highway Administration Long-term Bridge Performance Programme initiated an International Bridge Study by selecting a steel stringer bridge as a benchmark structure for structural health monitoring. As a part of this programme, the authors studied the application of the Long-Gauge Fibre Bragg Grating (LG-FBG) sensors on this bridge. This paper aims at illustrating the LG-FBG-related state-of-the-art technologies by taking the bridge as the test bed. (1) The concept of the LG-FBG sensor for area sensing is presented. Most fibre optic sensors measure point strains for local monitoring. In contrast, the developed LG-FBG area sensor has a long gauge (e.g. 1–2 m), and it can be connected to each other to make a sensor array for distributed strain measuring; (2) spectral analyses of the macro-strain time histories are performed to identify structural frequencies, and the results are compared with those estimated from acceleration measurements; (3) the neutral axis position of the girder of the investigated bridge is estimated from the recorded macro-strain time histories, and the results are compared with those from static truck tests and (4) a modal macro-strain-based damage index is applied for damage detection of the steel stringer bridge.

Keywords::

• long-gauge
• area sensor
• macro-strain
• dynamic measurement
• structural health monitoring

Acknowledgements

This work was sponsored by the National Science Foundation of China (51108076) and the Supporting Programme of the Twelve Five-year Plan for Science & Technology Research of China (2011BAK02B03). The second author would like to acknowledge the support from the Scientific Research Foundation of Graduate School of Southeast University and the Priority Academic Programme Development of Jiangsu Higher Education Institutions. We would particularly like to acknowledge the support from Mr Jeff Weidner during the field test and useful conversations with Drs F. Moon and A.E. Aktan from Drexel University.

Notes

^1. Email: [email protected]

^2. Email: [email protected]

^3. Email: [email protected]

^4. Email: [email protected]

^5. Email: [email protected]