Optical fiber sensor methods for nondestructive evaluation of bridges

Abstract

This report defines a present problem with U.S. bridges and suggests several reasons for bridge infrastructure deterioration and degradation, such as traffic overload, expired life cycles, environmental and operational conditions, and budget cuts. The most commonly used nondestructive evaluation (NDE) methods for determining the health of bridge infrastructure are summarized and compared. Advantages and disadvantages of each NDE technique are provided, and the lack of an adequate method which can quantitatively monitor the structural integrity of bridges is noted.

This report then discusses the possibility of health monitoring sensor systems for the quantitative NDE of bridge infrastructure. Several types of sensors that may be used to collect paSSlve and quantitative data related to the structural integrity of bridges are evaluated, and the extrinsic Fabry-Perot interferometric (EFPI) fiber optic sensor is suggested as the preferred sensor.

The fabrication processes and operational principles of EFPIs are presented. Two case studies which demonstrate the performance of EFPI sensors when used in health monitoring sensor systems are provided. Finally, a design criteria checklist suggests several questions that need to be asked (or more thoroughly defined) concerning the usefulness, reliability, durability, and sensitivity of EFPI-based health monitoring sensor systems.