Temperature and deformation measurement on public usage objects by using FBG sensors

Authors: Paweł Wójcicki MS, Marek Skłodowski PhD, Piotr Pawłowski PhD
Institute of Fundamental Technological Research, Intelligent Technology Dept.
Polish Academy of Science
Pawińskiego 5B, 02-106 Warszawa

Temperature and deformation measurement on public usage objects by using FBG sensors

A very important question arising in various situations in civil engineering is how to measure deformations and other environmental variables for example temperature. During centuries people try to collect this primary information in various ways. Gathering that information continuously or periodically gives one a vision about what happened with object of study in past, present and what may happen with it in future.
To provide correctly prepared acquisition which is a quite complex process it is necessary to use various methods and to chose among them an adequate method suitable to the problem under study.
Safety is the most important issue in the subject under discussion thus, all structures of public usage have to meet the requirements of certificated standards. These regulations guarantee to design construction with surplus in calculated strength values. These values counteracts static and dynamics forces. This is a correct method to provide very good safety level but in some cases during materials preparation or assembling elements to final construction may appear some faults that may have impact on whole object or be only a local defect. Additionally sometimes human induced vibrations have very important but unpredicted impact on the construction. It happens for example on sport stadiums,
mining-areas, bridges, tunnels, dams, etc. As it is it’s impossible to predict all phenomena interacting with future object, nowadays researchers are working on new technologies dedicated to structural health monitoring and doing analysis that can warn people about sudden dangers.
One of the technologies resulting from the research on SHM are optical fiber techniques of deformation, strain, displacements, temperature and other measurements useful for monitoring of structures. There are a few fiber-optic sensing technologies like:
SOFO, FBG, EFPI and other. All of them can find a place in specific areas of monitoring in civil engineering.
Authors installed FBG strain, deformation and temperature sensors on two real objects of public usage. First object is a football stadium where one of main column of a grandstand and three joints from truss of roof were equipped with sensors. Second structure is a bridge connecting two wing of Institute of Fundamental Technological Research building destined to personnel usage. Both sensor systems successfully passed usability tests and their are ready for further development. Presented results are preliminary results of possible data measurement analysis.
Both sensor networks are ready to be developed in a more advanced monitoring system, with computing algorithms designed to predict and warn about possible danger from human behavior inducted vibrations. Finally a proposition of a complex monitoring and warning system for football stadium will be shown .