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Adaptation of methods for cyclo-stationary processes for noisy structural health data
Fischer, Cyril ; Bayer, Jan ; Náprstek, Jiří ; Urushadze, Shota
In structural health analysis, various techniques, including indirect measurement via monitoring vehicles, often yield data with significant randomness and insufficient frequency separation. Conversely, the desired attributes under scrutiny are periodic in nature. Thus, methodologies designed to identify cyclo-stationary properties within noisy data can be adapted for such scenarios, assuming an adequate length of the recorded data.
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Protection of historic buildings against vibrations
Urushadze, Shota ; Pirner, Miroš ; Bayer, Jan
The presented heritage procedure was developed in 2018-2021 as part of the NAKI project no. DG18P02OVV040, entitled 'Monuments in Motion', funded by the Ministry of Culture of the Czech Republic. The basis for the design of this heritage procedure is the 30-year activity of Prof. Pirner, Ing. Urushadze and Ing. Bayer in the field of technical seismicity and building dynamics in general. The proposed heritage procedure is actually a methodological guide on how to proceed if there are any failures or negative effects that could be related to vibrations, as well as how to deal with them. For each of the various points of the procedure examples are given from our many years of practice. In general, these investigations involve theoretical and experimental analysis including in situ investigations, non-destructive and laboratory tests on models, using finite element modelling.\n
Plný tet:  PDF; PDF; PDF
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Moving dynamic test loads for road bridges - a case study
Bayer, Jan ; Urushadze, Shota
Two types of dynamic testing load for bridges - driving sprung mass and driving impulse load - areexamined from the drive-by identification point of view. Numerical studies in ANSYS using contact elements and in MATLAB using a modal solution together with coupling force were performed. Equations for the estimation of the impulse load caused by a rolling cogwheel were suggested. The experiments confirmed that a driving impulse load is more efficient in exciting bridge vibrations. This, together with the fact that impulse loading is not sensitive to surface roughness, leads to the conclusion that, as a method for bridge health monitoring, impulse loading is more promising than using a driving sprung mass
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Summary research report from vibration measurements at ELI Beamlines research centre
Pospíšil, Stanislav ; Bayer, Jan ; Hračov, Stanislav ; Urushadze, Shota
The report describes the procedures and results of a set of dynamic measurements of micro-seismic vibrations of the floors and walls in ELI Beamlines research centre. The measured vibration level is assessed with respect to NIST criteria, which are applied only in case of areas with the highest vibration requirements. The special attention is also paid to assessment of several different improvements of the floors that were performed locally in the selected points. The improvements were made in order to decrease the vibration level also from a short-term perspective, which was omitted by methodology used and proposed by the client.
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Proposal for loading tests of bridges - simulation and laboratory experiments
Bayer, Jan ; Urushadze, Shota ; Černý, Miloš
A new dynamic load testing of bridges is proposed and theoretically investigated. A transient analysis of passing vehicle over a bridge in ANSYS and an analytical program in MATLAB for the transient solution of piecewise linear mechanical structures were developed to assess the effects of the proposed dynamic load on a bridge model. According to the first laboratory experiments, it seems that the proposed travelling impulse load could surpass some of the shortcomings and limitations of the currently applied methods of bridge testing. The investigation is a part of a project aimed at drive-by identification of dynamic properties of bridges and further experimental and analytical research will follow.
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Experimental study of horizontal forces of pedestrian dynamics
Urushadze, Shota ; Pirner, Miroš
At present similar detailed examination of pedestrian dynamics has been brought about chiefly by the requirements of determining the loads on footbridges. In their case – contrary to bridges – the magnitude of dynamic response is more important than that of static response, as it determines also the serviceability of the footbridge with reference to pedestrian comfort. The forces frequencies of step or strides for different walking velocities is the most important for the further analysis and analysis of the mechanisms.s.
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