Instytut Podstawowych Problemow Techniki PAN w Warszawie

Poland

Instytut Podstawowych Problemow Techniki PAN w Warszawie

Poland

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Dyniewicz B.,Instytut Podstawowych Problemow Techniki PAN W Warszawie | Sekula K.,Firma CONTEC W Llomiankach | Debowski T.,Instytut Podstawowych Problemow Techniki PAN W Warszawie
Drogi i Mosty | Year: 2010

For proper operation of a railway system, identification of the track parameters is necessary. In order to perform the monitoring, a numerical model of the railway system is required. The model should be as accurate as possible but it should also ensure moderate numerical costs of the computations. The paper presents experimental results taken in situ. The measurements were performed using piezoelectric sensors of a rectangular plate shape. The experimental measurements have been compared to the results of numerical simulations obtained using the method of space-time finite elements method. The effectiveness of the numerical simulation in modeling of the track dynamics has been proved. © Copyright by Instytut Badawczy Dróg i Mostów, Warszawa 2010.


Szelazek J.,Instytut Podstawowych Problemow Techniki PAN w Warszawie | Gutkiewicz P.,Instytut Podstawowych Problemow Techniki PAN w Warszawie | Mackiewicz S.,Instytut Podstawowych Problemow Techniki PAN w Warszawie
Drogi i Mosty | Year: 2011

Paper presents ultrasonic testing of stress changes in elements of steel structure. Basis of ultrasonic method are explained, formulas to calculate stress values based on changes of measured time of flight of ultrasonic pulses are given. Stress evaluation was based on both elastoacoustic effect and deformation of element under test. Ultrasonic probeheads used in measurements and measuring device are described. Results of stress monitoring in two elements of steel railroad bridge are presented - in I-section girders and diagonal truss member. Stress changes registered during passages of rail vehicles of various mass, traveling across the bridge with various velocities, in both directions are presented. Readings taken with two channel equipment during passage of cargo train showed asymmetry of stresses in both girders.


Jozwiak-Niedzwiedzka D.,Instytut Podstawowych Problemow Techniki PAN w Warszawie | Sobczak M.,Instytut Podstawowych Problemow Techniki PAN w Warszawie | Gibas K.,Instytut Podstawowych Problemow Techniki PAN w Warszawie
Road and Bridges - Drogi i Mosty | Year: 2013

The purpose of this research was to determine the carbonation depths in concrete containing calcareous fly ash. Eleven concrete mixes with the same water-binder ratio w/b and with different amounts of calcareous fly ash have been prepared in laboratory. In the test series I the mixes were produced with five blended cements containing different amounts of the following supplementary cementitious materials: calcareous fly ash, siliceous fly ash and granulated blast furnace slag. The second test series was produced with calcareous fly ash replacing 3 0% of the cement by weight. The maximum depth of carbonation in concrete was determined using the phenolphthalein method. The progress of the carbonation front was established by analysing polished thin sections of concrete under a polarizing microscope in transmitted light. The most resistant to carbonation was the concrete containing, beside clinker, 14.3% of calcareous fly ash as a cementitious material. The specimens of concrete containing different amounts of calcareous fly ash were compared and no significant variations were found both in the rate and depth of carbonation. On the other hand, the rate of advancement of carbonation front was higher in concrete containing calcareous fly ash as compared to the reference concrete without admixtures.


Dyniewicz B.,Instytut Podstawowych Problemow Techniki PAN W Warszawie | Bajer C.,Instytut Podstawowych Problemow Techniki PAN W Warszawie
Drogi i Mosty | Year: 2010

The paper presents algorithms for numerical finite element analysis of vibrations of structures under a moving inertial load. Some problems of dynamics of the structure are complex to be solved by the finite element method applied to spatial variables and by the Newmark method used for time domain. Peculiar features of analytical solutions of differential equations describing vibrations caused by a moving point mass must effect also their numerical solutions. Large gradients of solutions, jumps or discontinuities of solutions is difficult to obtain by the numerical discrete methods. These methods require approximations and introduce errors, which are difficult to be estimated. In this paper we discuss numerical solutions which allow us to obtain accurate results in a full range of velocity of the inertial load.

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