Using fiber Bragg grating (FBG) sensors for vertical displacement measurement of bridges

M.H. Yau, T.H.T. Chan, D.P. Thambiratnam, Hwa Yaw Tam

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic research


In many bridges, vertical displacements are one of the most relevant parameters for structural health monitoring in both the short and long terms. Bridge managers around the globe are always looking for a simple way to measure vertical displacements of bridges. However, it is difficult to carry out such measurements. On the other hand, in recent years, with the advancement of fiber-optic technologies, fiber Bragg grating (FBG) sensors are more commonly used in structural health monitoring due to their outstanding advantages including multiplexing capability, immunity of electromagnetic interference as well as high resolution and accuracy. For these reasons, using FBG sensors is proposed to develop a simple, inexpensive and practical method to measure vertical displacements of bridges. A curvature approach for vertical displacement measurement using curvature measurements is proposed. In addition, with the successful development of a FBG tilt sensors, an inclination approach is also proposed using inclination measurements. A series of simulation tests of a full-scale bridge was conducted. It shows that both the approaches can be implemented to determine vertical displacements for bridges with various support conditions, varying stiffness (El) along the spans and without any prior known loading. These approaches can thus measure vertical displacements for most of slab-on-girder and box-girder bridges. Moreover, with the advantages of FBG sensors, they can be implemented to monitor bridge behavior remotely and in real time. Further recommendations of these approaches for developments will also be discussed at the end of the paper.
Original languageEnglish
Title of host publicationDynamics for sustainable engineering : proceedings of the 14th Asia-Pacific Vibration Conference, 5-8 December 2011, Hong Kong
PublisherDepartment of Civil and Structural Engineering and Department of Mechanical Engineering, The Hong Kong Polytechnic University.
ISBN (Print)9789623677318
Publication statusPublished - Dec 2011


  • Vertical displacement
  • Structural health monitoring (SHM)
  • Bridge
  • Fiber Bragg grating (FGB) sensors


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