Development of Theoretical and Experimental Dynamic Monitoring of Large-scale Building Structure

The object of research is the method of monitoring and assessing the technical condition of the large-sized building structure of the International Exhibition Center (Kyiv, Ukraine). The currently applied method of monitoring this structure is based on the use of deformation indicators. The indicators of this method do not allow estimating the global technical state of the structure. Taking into account the social importance of the structure, it is possible to use dynamic monitoring while monitoring its technical condition.In the course of the study, two independent finite element models of the controlled facility are developed in the SCAD (Russia) and NASTRAN (USA) software complexes. With their help, a modal analysis was made and the values of the frequencies and forms of the natural oscillations of the structure were determined. The natural measurements of its natural frequencies have been made. It is found that the difference between the calculated and natural values of natural frequencies does not exceed 3 %.In addition, version of an automated experimental control system is proposed, which includes the use of three-component accelerometers MS2002+, Geoscop software, controlled by the operating system MS Server.The received results testify to the efficiency of the use of frequencies and forms of natural oscillations in the system of monitoring the technical state of the given structure. In comparison with static deformation parameters, they allow estimating the global technical condition and determining the integrity of the structure

Investigation of the dielectric, optical and photorefractive properties of Sb-doped Sn2P2S6 crystals

International audienceIn this work we report results on electro-physical, optical and photorefractive investigations for Sb-doped Sn2P2S6 crystals. The crystals are obtained by two methods: the vapour-transport technique and the Bridgman technique using stoichiometric Sn2P2S6 composition with different amounts of antimony in the initial compound. The good optical quality of the crystals obtained with the Bridgman technique is underlined. The dependences of the photorefractive two-beam coupling coefficient and the grating build-up time are investigated at the wavelength of 633 nm. It is found that the sample doped with 1.5% of Sb is characterized by an optimal combination of the main photorefractive parameters exhibiting a fairly high two-beam coupling coefficient (up to 20 cm-1) and a short response time (1.3 ms) that is the shortest among all the previously studied Sn2P2S6 crystals in the red spectral region