This article deals with the issue of fire safety monitoring of wooden buildings. Wooden buildings currently represent a quick and relatively inexpensive option for acquiring a family house. However, with regard to the building material and its flammability, the construction possibilities are strongly regulated by standards. The aim of this paper is to describe the possibilities of monitoring temperature changes during a simulated fire using optical fiber and a distributed temperature measurement system (DTS). The DTS system uses the principle of stimulated Raman scattering, which allows longitudinal temperature measurements with a spatial resolution of 1 m. The increase in spatial resolution was achieved by winding the optical fiber into 5 cm diameter rings, with a fiber length of 3 m in each ring. The measuring rings of optical fiber were attached to fabric arranged in a rectangular grid. This fabric with the rings was then placed at the surveyed locations in the construction panels. During the temperature loading of the test samples with the gas torch, temperature monitoring was carried out both on the reverse side of the samples and in the inner layers. The results showed that this system with conventional multimode optical fibers can measure temperatures ranging from 20 °C to approximately 500 °C. This method offers the possibility to accurately monitor the temperatures of wooden buildings, including the inner layers of the building panels. The proposed method can therefore be used to thoroughly verify the fire safety of wooden buildings and their components.
The article describes a comparative measurement of a classical seismic sensor and a fiber-optic interferometric sensor for the perimetric applications. We created and proposed technically and financially the simplest interferometric sensor (type two-arm Mach Zehnder). A test polygon was created where were analyzed the vibration-acoustic manifestations caused by the 20 test subjects. The article describes original results that clearly point to the high sensitivity of the interferometric sensor.
Road car transport is today the main species of cargo and passenger transport. However, car transport is accompanied by large negative effects with adverse environmental impacts. Therefore, it is an effort to shift part of the transported costs to rail transport. But the problem is vibrations which created the passing vehicles. The vibrations are transmitted over the rails and the railway infrastructure into the rock environment. These vibrations can adversely affect buildings around the railroad. This article presents a comparison of vibration measurements using a classical commonly used seismic sensor and innovative fiber-optic interferometric sensor. Presented results are based on the real measurements of train traffic. Presented results can serve as a basis for mathematical models which predict the future load of objects in the vicinity of railway tracks.
The undesirable dynamic effects of harmonic vibrations due to various devices and technologies are commonly monitored using by seismic stations operating on the principle of mechanical vibration systems (using on horizontal foundation structures or rock mass) or by resistance strain gauges (using e.g. on vertical concrete or steel elements). Modern, progressively evolving alternative to monitor these dynamic effects are methods based on fiber-optic principle. There is used fiber Bragg grating (FBG) or fiber-optic interferometric sensors. At the experimental level the article presents results comparison of conventional approaches to the monitoring of harmonic vibrations and approaches based on fiber-optic principle. Data was process in both amplitude and frequency domain.
Monitoring of building structures is an integral part not only during the phase of construction but also during their use throughout their lifetime. Fiber optic technology offers a number of unrivaled features and forms an interesting alternative to these applications. From the point of view of the safety of large building structures such as buildings, bridges or tunnels, increased attention should be paid to the reliability of monitoring devices. One option is to duplicate standard strain-gauge sensors with modern fiber optic sensors such as Bragg grating. This article brings a new hybrid sensory element, which consists of a Bragg grating and a standard foil strain gauge. The proposed sensor was tested in concrete structures and loaded with force and temperature effects. The results show the functionality of the proposed hybrid sensor implemented in concrete structures and the long-term reliability and independence of both parts of the hybrid sensors.
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