Wyniki wyszukiwania - Biblioteka Nauki

1

Analysis of harmonic vibration of cable-stayed footbridge under the influence of changes of the cables tension

100%

Pakos W.

Studia Geotechnica et Mechanica

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2015

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tom Vol. 37, nr 3

63--71

EN

The paper presents numerical analysis of harmonically excited vibration of a cable-stayed footbridge caused by a load function simulating crouching (squats) while changing the static tension in chosen cables. The intentional synchronized motion (e.g., squats) of a single person or group of persons on the footbridge with a frequency close to the natural frequency of the structure may lead to the resonant vibrations with large amplitudes. The appropriate tension changes in some cables cause detuning of resonance on account of stiffness changes of structures and hence detuning in the natural frequency that is close to the excitation frequency. The research was carried out on a 3D computer model of a real structure – a cable-stayed steel footbridge in Leśnica, a quarter of Wrocław, Poland, with the help of standard computer software based on FEM COSMOS/M System.

2

Pomiarowe metody dynamicznych analiz konstrukcji przemysłowych na przykładzie stropu pompowni

51%

Grosel J. , Sawicki W. , Pakos W.

Inżynieria i Budownictwo

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2015

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tom R. 71, nr 10

525--529

PL

Scharakteryzowano badania i analizy oraz omówiono wyniki pomiarów drgań maszyn (pomp) oraz konstrukcji wsporczej pod maszyny. Z uwagi na to, że przyczyna nadmiernych drgań mogła dotyczyć zarówno konstrukcji, jak i maszyn, przeprowadzono różne rodzaje pomiarowych analiz dynamicznych (OMA, EMA, ODS).

EN

The results of measurements of vibrations machines (pumps) and support structures using different measurements techniques and different methods of data processing are presented and discussed in the paper. Failure to comply with the ISO 10816-3 by pumps located on the reinforced concrete ceiling were the direct reason of the tests. Because the excessive vibration could be caused by both the construction and the machinery, the different types of measuring dynamic analysis (OMA, EMA, ODS) were carried out.

3

Kinematically excited parametric vibration of a tall building model with a TMD - Part 2: Experimental analyses

45%

Majcher K. , Wójcicki Z. , Grosel J. , Pakos W. , Sawicki W.

Archives of Civil and Mechanical Engineering

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2014

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tom Vol. 14, no. 1

218--229

EN

This paper constitutes the second part of the article Kinematically excited parametric vibration of a tall building model with a TMD. Part 1: numerical analyses (ACME, in press) by K. Majcher and Z. Wójcicki, which presents the results of theoretical research. This paper presents the experimental verification of those results. The experimental studies were carried out with the use of an especially designed physical model of a tall building, which rested on an earthquake simulator – a shaking table – created for this project. The simulator was used to generate several types of kinematic excitations: harmonic ones, superpositions of harmonic ones and, finally, ones generated on the basis of real seismograms. Vibrations were kinematically excited in the horizontal and vertical directions independently and simultaneously. The vertical component of the earthquake causes the pendulum suspension point to vibrate, thus exciting the pendulum parametrically. The theoretical study indicated a significant influence of this parametric excitation (parametric resonance) on the effectiveness of the Pendulum Tuned Mass Damper (PTMD). Therefore, the experimental analyses were especially focused on the parametric effects' impact on: the PTMD's ability to reduce the building's vibration, and the possibility of parametric resonance of the building due to parametric resonance of the PTMD.

4

Experimental research of cable tension tuning of a scaled model of cable stayed bridge

45%

Pakos W. , Wójcicki Z. , Grosel J. , Majcher K. , Sawicki W.

Archives of Civil and Mechanical Engineering

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2016

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tom Vol. 16, no. 1

41--52

EN

The paper describes the idea and the algorithms of a method for reducing the resonant vibration of the cables in a footbridge. The method relies on change of the static tension in chosen cables of the footbridge. The changes in static tension are introduced when resonance vibration occurs. The paper delineates empirical research employed to experimentally verify the numerical prediction. It has been demonstrated that it is possible to select some stay cables in which applicable change in static tension force value ensures amplitude reduction of forced resonance oscillations of any cable of the whole system. The choice of cables and the magnitude of tension change in them were based on the sensitivity analysis of an eigenproblem formulated in accordance with second order theory. The experimental research was designed to demonstrate practical effectiveness of amplitude reduction of stay cable resonant vibration method. A physical laboratory model of the footbridge was built in compliance with dimensional analysis on a scale of 1:10. Operational Modal Analysis (OMA) method was applied to identifying modal characteristic of a footbridge model.

5

Badanie drgań dużej konstrukcji przemysłowej

38%

Wójcicki Z. , Grosel J. , Mironowicz W. , Sawicki W. , Brząkała A. , Majcher K. , Pakos W.

Materiały Budowlane

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2009

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tom nr 3

132-136

6

Eksperymentalna i teoretyczna analiza dynamiczna konstrukcji

38%

Wójcicki Z. , Grosel J. , Sawicki W. , Majcher K. , Pakos W. , Brząkała A.

Inżynieria i Budownictwo

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2010

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tom R. 66, nr 12

706-709

PL

Opisano aparaturę do pomiarów dynamicznych wielkich konstrukcji inżynierskich i budowlanych. Przedstawiono przykłady jej wykorzystania do dynamicznych analiz różnych konstrukcji i modeli fizycznych. Stwierdzono, że w analizie konstrukcji inżynierskich i budowlanych powinny być jednocześnie prowadzone analizy teoretyczne i eksperymentalne w celu weryfikacji i walidacji modeli MES.

EN

Especially was presented an equipment for nondestructive research i.e. system for dynamic measurements of giant engineering structures. In paper is also some illustrative examples of usage of this system to dynamical analysis of different structures and models of structures. The authors propose that a new approach become the recommended standard in the analysis of engineering and building structures. According to them, both theoretical and experimental research should be carried out simultaneously in order to verify and validate FEM models.