Experimental validation of fiber Bragg grating sensors for steel girder strain characterization

Although several Fiber Bragg Grating (FBG) based transducers have been successfully applied to the measurement of strain and temperature on civil engineering applications, important research work must be done to obtain transducers able to be used out of the laboratory. One of these research topics are the study of good interfaces between the optical fiber and the structural part to be measured. In this work a wide range of fixing techniques and interfaces have been investigated for fiber Bragg grating based transducers. Several transducers were constructed and fixed to a steel girder. Conventional strain gauges and professional displacement metering devices was added to the test specimen to make comparisons. A complete characterization setup using a laboratory test machine to test the transducers was designed. The test included several static and dynamic cycles and was applied to the steel girder while all the transducers were monitorized simultaneously. Results obtained with traditional and with the optical fiber mentioned technologies show a very good agreement