Bragg Grating and BOTDR Fiber Optic Principles Applied for Real-Time Structural Monitoring-The MONICO Project

摘要

Structural engineering is a field of engineering dealing with the analysis anddesign of structures supporting or resisting various loads. Studies of structuralengineering requirements, specifically for densely populated areas, have indicated theneed for high safety standards particularly in structural monitoring having in mindlatest shifts from construction costs to life cycle costs and lifetime performanceincluding safety and use. Structural monitoring is now being supported by variousemerging technologies especially in areas of high seismicity where structuralmonitoring can be regarded of particularly high importance. Optical sensingtechnologies have a lot to offer in the field of structural monitoring providing the basisfor condition assessment before, during or after any event. Structural monitoring basedon fiber-optic technologies provide real-time, wireless and remote deformationsensing capabilities making them ideal regarding safety of vulnerable tunnel crosssectionsor sections where very high standards of safety are required. Quick andreliable structural assessment can be enhanced with integrated software that collectsand processes the data and assesses the structural reliability of the lining. Opticalsensing technologies are most of the times supported by the above algorithms and aretechnologically progressing day by day. However it is quite important that the alreadyexisting and emerging deformation technologies are evaluated and optimised so thatthey alone, or in combination, can provide optimal performance in the structuralsensing of structures and particularly tunnels. The MONICO EC Project hasdeveloped a prototype system consisting of an optimized fibre optics baseddeformation-sensing system for real-time measurement of deformations of reinforcedconcrete linings in tunnels and a Decision-Support-System (including user interfaceand decision suitable algorithms) that can drive proactive maintenance and earthquakerisk management and can assess the structural reliability of the monitored lining underoperating and seismic loads. Through this paper, the technologies, algorithms andsupporting software components will be presented together with the results of the finallarge-scale tests of the MONICO project.