A building structure health monitoring system based on the characteristic of TFBG

This paper introduces a new method of central wavelength of migration detection in fiber Bragg grating sensors based on the transmission properties of the main mode and side mode of Tilted fiber Bragg grating, and make it into a building structure health Monitoring System. In order to separate temperature effect with fiber Bragg grating, we use two adjacent FBG (one was used for sense, another for reference) which have the same central wavelength but different grating length, by parallel connection to make a sensing probe. Fix the TFBG keep on to a PZT, which was applied a zigzag sweep voltage in 10 Hz. Then the main mode and side mode of TFBG periodically offset in the same direction, so that the spectrum signal from sensing probe can be demodulated. The photodiode makes the transmitted light intensity changed into electric current. Voltage is amplified to 0~5v by amplifier circuit. Then set the voltage to A/D card for data acquiring and analytical processing data for real time display of await strain. Experimental results show that it is feasible to demodulate action spectrum by TFBG (the resolution of micro-strain detection is 5 ^με ), which solved the cross sensitivity of FBG to temperature and strain. The scheme may serve as the important technical guarantor that change the planned overhaul mode to premonitory one for building structure, and it will finally realize the intelligence of anti seismic and reducing disasters. The system is stably and reliable, low cost.