HEALTH MONITORING OF CIVIL INFRASTRUCTURE BY USING

A MOIRE FRINGE OPTICAL FIBER ACCELEROMETER

Dae-Hyun Kim¹ and Maria Q. Feng₂

ABSTRACT

Acceleration can serve as one of the most important parameters to monitor integrity and

safety of civil engineering structures. However, one of the major obstacles preventing sensorbased

monitoring is the unavailability of reliable, easy-to-install, and cost-effective sensors. Civil

engineering structures place unique demands on sensors. Besides accuracy, sensors and their

cables are expected to be reliable, low in cost, light in weight, small in size, resistant to EM

interference, and long in service life. They are required to withstand harsh environments, be

moisture-, explosion-, lightning-proof, and corrosion-resistant. This paper presents a novel optical

fiber accelerometer system for monitoring large-scale civil infrastructure such as utility lifelines,

highway bridges, and buildings. Particularly suitable applications are in environments where

conventional electric accelerometers cannot be used due to strong electromagnetic (EM)

interference, electric spark-induced explosion risk, and cabling problems. The proposed optical

fiber accelerometer represents a novel integration of the moiré phenomena and fiber optics to

achieve a robust performance in addition to its immunity to EM interference, easy cabling, and

low cost. All of these make the proposed sensor ideal for applications in civil infrastructure

monitoring. A prototype sensor system has been developed, together with a real-time signal

processing software equipped with a unique compensation filter to increase the sensor’s dynamic

bandwidth. The experimental studies demonstrated the high-performance of the optical fiber

sensor system.

1 Post-Doctoral Researcher, University of California Irvine, CA 92697, USA, daehk@uci.edu

2 Professor, University of California Irvine, CA 92697, USA