Temperature and Strain Measurements with Fiber Optic Sensors for Steel Beams Subjected to Fire

This paper presents measurements of high temperatures using a Brillouin scattering based fiber optic sensor and large strains using an extrinsic Fabry-Perot interferometric sensor for assessing the thermo-mechanical behaviors of simply-supported steel beams subjected to combined thermal and mechanical loading. The distributed fiber optic sensor captures detailed, non-uniform temperature distributions that are compared with thermocouple measurements resulting in an average relative difference of less than 5 % at 95 % confidence level. The extrinsic Fabry-Perot interferometric sensor captures large strains at temperatures above 1000 degrees C. The strain results measured from the distributed fiber optic sensors and extrinsic Fabry-Perot interferometric sensors were compared, and the average relative difference was less than 10 % at 95 % confidence level.