Fiber-optic sensors for monitoring the stress-strain state of construction objects

Abstract

For the timely detection of significant changes in the stress-strain state in the bearing elements of various building structures, which may lead to a deterioration of the technical condition of the object or transfer it to the emergency state, the use of fiber-optic sensors is proposed. The main advantageous characteristics of fiber-optic sensors, describing the promise of their application for practical applications, are disclosed. As a parameter recorded by the measuring transducer, the fiber-optic sensors use the intensity of the light wave. The mechanism of changing the optical intensity can be due to reflection, absorption, refraction of light rays passing through the measurement zone. The authors have developed a fiber optic attenuator type deformation sensor capable of controlling mechanical deformations of structural elements caused by disturbed internal geometric characteristics, destruction of structural integrity and negative influence of external weather conditions, seismic factors, temperature drops during operation. When developing the design of a fiber-optic sensor, the fundamentals of circuit design of measuring devices, methods of geometrical and fiber optics are used. As a basic measuring transducer, a fiber-optic microdisplacement transducer with a limiting attenuator is used, in which the intensity of the optical signal is modulated by changing the position of the attenuator placed in its path or increasing the optical power. A design-structural diagram of a fiber-optic micro-displacement measuring transducer and a block diagram and the design of a new sensor are presented. The principle of operation of an attenuator-type fiber-optic strain gauge is described.