Application of Fiber bragg Grating Sensors on Monitoring of Cables´ Tension

A new on-line monitoring method based on fiber Bragg grating (FBG) for cable tension of cable-stayed bridge is studied. The major structure of sensing head in the test of cable tension is an elastic annulus. The FBG is attached inflexibility to the exterior surface of annulus and form straight-through sensing head. Sensing head is installed between the anchor device and stow-board of funiculus holes of the cable-stayed bridge. Accompany with the changed outside pressure, the Bragg center reflective wavelength of optical fiber grating will be changed correspondly. According to this characteristic and through demodulating the Deltalambda_b, the value of the cable tension may be determined. The experiment results and theory indicate that the test system has good stability and linear response capacity, high intensity signal and signal to noise ratio, and has no request for test man, The measurement method for test of cable tension is practical and effective.