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Application of discrete wavelet transformation to defect detection in truss structures with rigidly connected bars

Knitter-Piątkowska A., Guminiak M., Przychodzki M.

Engineering Transactions

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2016

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Vol. 64, iss. 2

157--170

EN

The structures examined in this paper are bridge-type trusses that were previously used as railway viaduct support structures. The considered trusses are modelled as 2D and 3D structures. The lower chord bar of the considered structure can be loaded by external forces located outside the rigid nodes (the points where truss bars are connected). Hence, in the numerical experiment in terms of 2D approach, the truss structure consists of the set of two-node beam finite elements with three degrees of freedom per node and exact shape functions. According to 3D approach, the truss is described as the set of two-node beam elements with six degrees of freedom per node. Axial and twisting displacements of the element are described by linear shape functions and the bending is described by polynomials of the third order corresponding to Euler-Bernoulli beam fields of deformation. The defect (damage) in truss structure is modelled as the local stiffness reduction of one or two lower chord bars. The analysis of a structural response is carried out using the discrete wavelet transformation (DWT). The aim if this work is to detect the localization of damage provided that it exists in the considered structure and to examine whether the DWT will prove to be the effective tool to defect detection. It is expected that the disturbance of the response signal will appear in the vicinity of the point where the defect exists. The family of Daubechies 4 wavelet is implemented. Numerical investigation is executed based on signal analysis of structural static response. Some numerical examples are presented.

2

Wpływ temperatury na właściwości dynamiczne ram z lepkosprężystymi tłumikami drgań

Lewandowski R., Przychodzki M.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2016

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z. 63, nr 1/I

431--438

PL

W pracy omawia się wpływ temperatury na charakterystyki dynamiczne konstrukcji z wbudowanymi lepkosprężystymi tłumikami drgań. Właściwości tłumików są opisywane uogólnionym modelem Maxwella, a parametry modelu są funkcjami temperatury panującej w tłumiku. Wykorzystuje się zasadę superpozycji czasowo-temperaturowej. Charakterystyki dynamiczne konstrukcji z tłumikami drgań wyznacza się jako rozwiązanie problemu własnego. Podano i przedyskutowano wyniki przykładowych obliczeń.

EN

In the paper an influence of temperature on dynamic properties of frames with built-in viscoelastic dampers is analyzed. Properties of dampers are described with a help of the generalized Maxwell model with parameters depending on temperature in dampers. The time-temperature superposition principle is used. Dynamic characteristics of considered systems are determined as the solution to the eigenvalue problem. Results of exemplary calculation are presented and briefly discussed.

3

Neuronowy filtr Kalmana w aktywnej redukcji drgań konstrukcji budowlanych

Przychodzki M., Lewandowski R.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2008

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z. 74 [258]

291-298

EN

This paper is devoted to research on using artificial neural networks as the neural Kalman filters. The Kalman filters are widely used in the active control of building structures. There are described two types of neural networks worked as Kalman filters: linear neural filters and two-layer feedforward neural networks. The neural Kalman filters were tested in simulations of the active control of the building structure model. The results of numerical computations are presented in this paper.

4

Aktywna regulacja drgań konstrukcji ramowych obciążonych parciem wiatru

Lewandowski R., Przychodzki M.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2002

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z. 60 [197]

371-378

EN

In this paper, the heuristic active control method is described. The planar frame structures with active control system subjected to strong wind is considered in particular. Results of example calculation show, that the describing method makes possible significant reduction of displacements and accelerations of structures.