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Inspection of the technical condition of load-bearing structural elements of buildings and structures in the process of their construction and operation is an important issue at the present time. A fiber-optic monitoring system is proposed as a solution to the problem of early diagnosis of defects and damage to load-bearing building structures. A scheme has been developed for testing fiber-optic sensors, which make it possible to control the stress-strain state of monolithic reinforced concrete structures. For testing, a series of monolithic concrete beams of rectangular cross section has been made reinforced with fiber optics during their manufacturing. The values of mechanical stresses and deformations arising in beams under loading have been determined. Using the tested samples as an example, it has been established that the proposed fiber-optic monitoring system (FOMS) makes it possible to control stresses and deformations (and to predict the appearance and growth of cracks) in various building structures. The main element of the system is a hardware-software complex capable of estimating the parameters of a light wave at the output of the optical fiber. The distance from the installation site of the data processing unit to the measurement point can cover the area of 30 km. At this, fiber-optic sensors operate without additional power supply from a laser with the power of up to 30 mW. The proposed monitoring system has a low cost of one measurement point, it is easy to install, which is a good alternative to the electronic beacon-recorder device and the development of optical digital technologies in construction.

Construction and safe operation of buildings and structures in complicated geological conditions, in the conditions of dense development, is a vital issue for large, densely populated cities. Systems of monitoring the technical condition of the supporting structures of buildings based on the use of fiber-optic sensors have been developed. Fiber-optic sensors operate on a new method of controlling the parameters of a light spot using a hardware-software complex. The proposed monitoring system is quasidistributed and can determine the damaged and most stress-strained sections of the supporting reinforced concrete structures of buildings at the stage of their occurrence and take preventive measures to protect them. The monitoring system can perform the function of measuring pressure on the building structure and establish the damage zone and signal in case of a sharp change in parameters during the structure destruction. Using this system, it is possible to monitor the technical condition of building structures of the underground and aboveground parts of buildings and to monitor their integrity in real-time. A four-channel hardwaresoftware complex has been developed that uses the physical principles of measuring pressure on a concrete beam, as well as changing the refractive index during micro bending of an optical fiber of the G.652 type, which can be expressed through changing the light spot incident on the surface of the photodetector. The dependence of additional losses in an optical fiber on the applied force at a light wavelength of 650 nm has been obtained. [ABSTRACT FROM AUTHOR]

This paper reports a study into designing an information-measuring system that could be used in coal mines that are dangerous in terms of the explosion of coal dust and methane gas. The results of reviewing technical advancements in the field of fiber-optic system development are given. To solve the set task, prototypes of a fiber-optic sensor of a new type and a hardware-software complex were constructed. The research aims to improve the safety of workers at coal enterprises. The result of the theoretical research has established that additional losses related to a micro bending should be taken into consideration while accounting for the effect of photoelasticity. The fundamental difference between the idea reported here and existing analogs is the development of a hardware-software complex capable of working with a single-mode optical fiber of great length with a significant noise level. The data processing unit is equipped with a television matrix and can analyze changes in the pixels of a light spot. The proposed system is quasi-distributed; it controls individual points within a rock massif. The designed hardware-software system provides high noise immunity of measuring channels when the external temperature changes. The research results helped develop an information-measuring system for monitoring the deformation and displacement of rock massif layers based on fiber-optic sensors, capable of operating in an explosive environment. The system makes it possible to control several layers located in the roof of the workings, while the fiber-optic sensor may contain two or three sensitive elements that are connected to different channels. With a sharp fluctuation in pressure and an increase in the displacement parameter, the system triggers a warning signal about the danger. [ABSTRACT FROM AUTHOR]