Influence of vibrations on structures

One type of occasional structural load is a seismic load. Earthquakes and blasts are typical sources of vibrations, but vibration generated during urban tunnel construction can represent a significant problem. Evaluation of the harmful impact of vibrations transmitted through rock massif into buildings is solved using experimental measurements, detailed analyses of measured signals, knowledge of geological pattern and constructional analysis. Seismic load of structures due to earthquakes is solved using the EUROCODE 8 standard. The earthquake movements at a certain location on the surface are determined by an elastic response spectrum to the ground acceleration. Eurocode 8 puts emphasis especially on the robust foundations and simplicity of construction systems. It is also mentioned vibration effect on historical buildings and effect under the surface, for example, in mine spaces. Historical structures are usually even more prone to vibration damage than, for example, typical wood-frame homes. The greater concerns over historic structures arise from the design, structure age, building materials and building methods used. The peak values of vibration generated by earthquake decrease with depth; the decrease is faster in shallow layers compared with the deeper part. Technical vibrations differ from natural earthquakes, for a comparable value of maximum vibration amplitudes, especially in the frequency range of the signal and mostly its duration. Evaluation of technical seismicity is more complicated because there are usually used national standards. To document some common information about vibration effects on structures, some experimental measurements are presented. Examples of real wave patterns document common shapes and also signals with significant resonant vibrations. Very interesting is an example of resonant vibration that was generated as the influence of basin structures on the shape of wave patterns due to quarry blasts. To obtain complete information, measurement system has to keep sufficient parameters, especially the frequency range of the whole seismic channel, sampling frequency, and proper anchoring of the sensor. The basic methodology for evaluation of vibration on structures is outlined.Web of Science23331129

Influence of seismic events on shallow geotechnical structures

This paper deals with a summary of possible seismic loading of shallow geotechnical structures. It is known that seismic loading influences the underground structures much less than the structures on the surface, therefore, it is not usually taken into account. However, cracks or damage in lining occur due to vibration from time to time. Two effects of earthquakes are documented on these structures: an effect due to faulting and an effect due to vibration. At present, FEM is the most popular method to solve the above problems. Integrated earthquake simulation is the most frequent task that has a significant impact on seismic hazard and seismic risk estimations, and human actions against earthquake disasters. Three types of rock massif were defined for this study: soft rock, medium hard rock, and hard rock. More detailed description and sensitivity analysis are performed for circle cross-section of those structures. Sensitivity analysis was performed using soil interaction method according to Wang's methodology; change of lining diameter and elastic modulus of lining were tested. Thrust force must also be calculated for the no-slip condition. Graphs presented in this paper document individual relations between individual studied parameters. These results can be used as sufficient accurate final analysis while idealised conditions can be accepted.Web of Science22442141

Interface of Vibrating Wire Crackmeters for Distributed Measurement Networks

Import 05/08/2014V geomechanice, geotechnice, geologii, stavebnictví a mnohých dalších odvětvích je potřebné měřit relativně malá posunutí, respektive deformace, na různých zájmových objektech. Mezi nejrozšířenější a nejspolehlivější snímače na měření posuvů a deformací se řadí strunové snímače. Ve většině těchto aplikací je nutné sledovat více zájmových objektů najednou. Mnohdy je rovněž vyžadováno i komplexní sledování několika veličin – nejen deformací – na jednom zájmovém objektu. V takovýchto případech není účelné realizovat systém kontinuálního monitorování pomocí mechanických měřičů deformace nebo elektrických měřičů deformace vyžadujících spoluúčast člověka. Proto se využívají elektronické automatické měřicí systémy. Cílem této práce bylo navrhnout prototypové řešení rozhraní strunových čidel vhodné pro použití v průmyslových prostředích s větším výskytem elektromagnetického rušení připojitelné k distribuovaným měřicím systémům, které komunikují po sběrnici AIBus-2. Vlastní řešení určení vlastní frekvence odezvy strunových snímačů vychází z analýzy frekvenčního spektra signálu odezvy vypočítaného pomocí rychlé Fourierovy transformace.Relatively small displacement or deformation is necessary to measure on the various structures and objects under study in geomechanical and geotechnical engineering, geology, civil engineering and many other industries. Vibrating wire crackmeters are the most widespread and the most reliable sensors for the measurement of displacements and deformations. Multiple objects are necessary to measure simultaneously in most of these applications. Sometimes, it is also required comprehensive monitoring of several different variables - not only deformation – for one given object. In such cases, it is not practical to implement a system of continuous monitoring using mechanical or electrical strain gauges that required attendance of staff. Therefore, electronic automatic measurement networks are used. The aim of this work was to design solution of a prototype interface of vibrating wire crackmeters that is possible to apply in E-M noisy industrial environments connectable to a distributed measurement systems that used the AIBus – 2 protocol for communication. Determination of eigenfrequency of vibrating crackmeter response is based on analysis of frequency spectrum of signal response that is calculated using Fast Fourier Transform.450 - Katedra kybernetiky a biomedicínského inženýrstvívelmi dobř

Calendar and Switch-Board Interconnection

Tato bakalářská práce se zabývá možností propojení pobočkové ústředny Asterisk s kalendáři z Microsoft Exchange Serveru 2010. Přitom rozebírá protokoly CalDAV, WebDAV, iCalendar a SOAP.This bachelor thesis discuss interconnection between Asterisk private branch exchange and Microsoft Exchange 2010 calendars. It describes CalDAV, WebDAV, iCalendar and SOAP protocols.

An initial study evaluating vibration effects of wind turbine

Jedním z negativních vlivů větrných elektráren na okolní prostředí jsou vibrace. V článku je představen výsledek analýzy experimentálního seizmologického měření ve větrném parku Horní Loděnice – Lipina. Časově-frekvenční spektra záznamů naměřených v okolí jedné z elektráren ukazují při ustáleném větru na generování harmonických kmitů do okolí. V článku jsou uvedeny výsledky této analýzy.Seismic vibrations represent one of the negative influences of wind turbines on their surroundings. Results of analysis of experimental seismological measurement performed in Horní Loděnice – Lipina wind farm are presented in this paper. Time-frequency spectra calculated from measured wave patterns realized around one wind turbine documented generation of harmonic waves into massif. Results of this analysis are presented in this contribution

Analysis of technical seismicity records using wavelet transform - packet decomposition

Článek představuje výsledky analýzy digitálních záznamů technické seizmicity. Výsledky jsou ukázány na svislých složkách záznamů vibrací vyvolaných například beraněním piloty nebo hutněním štěrkového podkladu. K analýze je použit paketový rozklad do 16 frekvenčních hladin, který je založen na waveletové transformaci digitálních signálů s využitím ortogonální Daubechiovské mateřské báze SYM 20.Analysis results of digital records of technical seismicity are presented in this paper. These results are shown on vertical components of signals generated e.g. by pile driving or compaction of graveled base. Packet decomposition into 16 frequency ranges is used for analysis; these decompositions are based on wavelet transform of digital signals using orthogonal Daubechies mother base SYM 20

One decade of wavelet transform application for mining induced seismic events on Institute of Geonic

This paper summarizes one decade of researches that were localized on wavelet transform apply to mining induced seismic events. Main topics and partial results are documented. The newest results that present using of wavelet transform of seismic events for cluster analysis are also presented. Contribution is replenished with published papers

Evaluation of seismic effect of traffic-induced vibrations

Vibrations caused by moving vehicles are necessary to take into account if roads are situated in populated areas. The vibration of ground induced by moving vehicles is a complicated problem. Values of induced vibrations depend on several parameters, i.e. the parameters of vehicles, quality of roads or railroad tracks, and subsurface geological patterns. It is possible to derive initial information about the vibration effect from experimental measurements. Four individual phases are usually studied in the surroundings of roads or railroads: generation of vibrations, propagation of seismic waves through soils, influence of vibrations on the nearest structures, and a reduction of vibrations using wave barriers. This paper presents a methodology of seismological measurements in the surroundings of the road or railway and a detailed interpretation of digital data from seismological viewpoint. Frequency range of seismic channel was 2 – 200 Hz, so that the detailed interpretation may be performed in the time-frequency domain. Relations between the distance and maximum amplitude of vibration velocity were compiled. The relations are relatively complicated, especially in the distance of more than 7 – 10 m. We suppose that described effect is induced by local surface and subsurface geological pattern.Web of Science201373