Project Title: Long Gage Interferometric Fiber-Optic Sensors For Damage Detection In Bridge Structures Investigators: Dr. Jeffrey Laman, Dr. Karl Reichard Research Assistants: Andy Doller     Funding Agency: NCHRP - IDEAS     Project Duration: October 1998 to August 2000 References: McDonagh*, M.D., J.A. Laman, T.E. McDevitt, and K.M. Reichard. "Long Gage-Length Interferometric Fiber Optic Sensor for Damage Detection," Nondestructive Testing and Evaluation, Vol. 14, No. 5, May 1998, pp. 293-321.   Laman, J.A., K. Reichard, and A.J. Doller. "Long-Gage-Length Interferometric Fiber Optic Sensors for Condition Assessment in Bridge Structures," Proceedings of the ASCE 2000 Structures Congress, Philadelphia, Pennsylvania, May 2000, 10 pages (CDROM).     This optical sensor development project has researched, developed, and refined an innovative long gage-length, optical fiber based sensing system to be used for the purpose of bridge structure condition assessment and damage detection. Two distinct detection system innovations are derived from the present project: a robust optical sensing system and a long gage-length sensor. The research was deliberately designed as a logical sequence of research and development consisting of (1) an investigation into the basic science of optical cable; (2) engineering of a fiber-optic-based condition assessment system; (3) development and evaluation of damage detection techniques; and (4) full-scale implementation of the system and damage detection methodologies on an existing Pennsylvania bridge. The program determined the relationships between the configuration of a long gage-length fiber-optic sensing system and the ability to detect damage in large civil structures. The system developed and optimized in the laboratory as preliminary research has shown the concepts to be feasible and implementable.
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