Publications

Badania lepiszczy asfaltowych w reometrze dynamicznego ścinania – relacje konstytutywne lepkosprężystości, hipersprężystości i lepkohipersprężystości

Evaluation of the effect of processed plastic additives on the properties of paving grade bitumen

Asfalty modyfikowane są powszechnie stosowane w budownictwie drogowym. Znane są różne metody modyfikacji, a za najlepszą i najczęściej stosowaną uznaje się modyfikację polimerem SBS. W niniejszym artykule zaprezentowano wyniki badań nad możliwością modyfikacji zwykłych lepiszczy drogowych w inny sposób, tj. przy wykorzystaniu przetworzonych tworzyw sztucznych pochodzących z recyklingu. Warunkiem wyjściowym dla tego typu modyfikacji jest zapewnienie stabilności wytworzonego materiału oraz niepogorszenie jego właściwości funkcjonalnych w porównaniu do lepiszcza bazowego. W pracy zaprezentowane zostaną wybrane wyniki badań doświadczalnych przeprowadzonych na materiałach uzyskanych ze zmieszania konwencjonalnych asfaltów drogowych 50/70 oraz 70/100 z dodatkami wytworzonymi z PP, PS, LDPE, HDPE (oraz ich mieszankami). Dodatki te uzyskano w procesie pirolizy przy różnych technologiach wytwarzania z uwzględnieniem różnych wartości temperatury i czasu przetwarzania. Przeprowadzono badania podstawowe na 56 różnych kompozycjach asfaltu i dodatku w celu wyłonienia potencjalnie najlepszych wariantów do dalszej poszerzonej analizy. Zaproponowano metodę obiektywnego wyboru najlepszych mieszanin asfaltów z dodatkiem. Nie jest to klasyczna metoda rankingowa (przyznawanie punktów), a metoda bazująca na funkcji celu będącej sumą trzech funkcji składowych odpowiadających poszczególnym parametrom z odpowiednimi wagami. Metoda ta może być dość swobodnie kształtowana poprzez dobór wag albo odmienne propozycje funkcji składowych. Na tej podstawie wyłoniono dodatki, które mają najkorzystniejsze właściwości pod względem zastosowania do produkcji mieszanek mineralno-asfaltowych.

Modelowanie numeryczne badania TSRST w celu określenia przydatności wybranych modeli konstytutywnych

No abstract is provided for this article.

Symulacja numeryczna i weryfikacja doświadczalna testu rozciągania płaskownika z uwzględnieniem teorii sprężysto-plastyczności dużych deformacji

No abstract is provided for this article.

Ustalony i nieustalony przepływ ciepła przez niejednorodne przegrody budowlane

No abstract is provided for this article.

Buckling resistance assessment of steel I-section beam-columns not susceptible to LT-buckling

The authors focused on buckling resistance assessment of steel-I-section perfect beam-columns of the cross-section class 1 and 2, not susceptible to LT-buckling and subjected to compression and one directional bending about the section principal axes y–y or z–z. These assumptions lead to the case of elements considered as only sensitive to the flexural failure including second order in-plane bending and compression. The stability behaviour of elements subjected to different bending configurations and different static schemes was investigated through comprehensive numerical study with use of the finite element method. Geometrically and materially nonlinear analyses GMNA in case of perfect beam-columns and GMNIA fo the imperfect ones were carried out in reference to shell and beam element models. Static equilibrium paths accounting for pre- and post-limit behaviour were determined with use of the incremental-iterative algorithm taking into consideration displacement-control parameters. An analytical formulation for a quick verification of the perfect I-section beam-column resistance is proposed. Finally, the global effect of imperfections is also investigated using GMNIA. The verification method developed for perfect elements is extrapolated for imperfect beam-columns. The good agreement of the proposed analytical formulation is shown through an extensive comparison with more than 3500 results of finite element numerical simulations conducted with use of ABAQUS/Standard program.

Evaluation of fatigue life of high modulus asphalt concrete with use of three different definitions

The fatigue life of an asphalt mix is defined as the number of load repetitions at which the crack initiation phase ends and macro cracks start to grow (crack propagation/failure phase). The problem is how to determine in an objective way this number of repetitions. Three different definitions for the fatigue life were applied and compared to each other using three different Polish asphalt mixes. Twelve beams of SBS-modified asphalt mix (mix A), 12 beams of the HiMA mix (mix B) and 14 beams of an ordinary Polish asphalt mix (mix C) were tested in a four-point bending (4PB) device in controlled deflection (strain) mode at 10 Hz and 10°C. During fatigue development, three different phases typically may be indicated (plus so-called transition zone). Based on the locations of the fatigue life (obtained on the basis of three different definitions) with respect to the characteristic fatigue phases a proposal for a new fatigue life definition was made. The location of this fatigue life definition will always fall in the transition zone between the fatigue initiation phase and the failure phase. The main advantage of this definition is that it can be used in automatic processing of fatigue data.

On the Resistance Evaluation of Lateral-torsional Buckling of Bisymmetrical I-section Beams Using Finite Element Simulations

Evaluation of the lateral-torsional buckling resistance of bisymmetrical I-section beams using finite element method was widely discussed in the paper. Numerous FEM simulations with regard to the stability behavior of steel structural elements subjected to bending about the major principal axis were performed. The use of different finite element modeling techniques and their influence on obtained results were presented by the authors. The ultimate state of both perfect and imperfect elements was assessed. Considerations were concerned with hot-rolled wide flange HEB and narrow flange IPE section beams. Idealization of boundary conditions of FEM models complies with the assumptions used in the analytical formulation of stability problems of thin-walled beams. Geometrically and materially nonlinear analyses GMNA and GMNIA preceded by LBA analyses were carried out. Numerical simulations were conducted with use of ABAQUS/ Standard program.

Analiza podatnej nawierzchni drogowej na podłożu z inkluzją w postaci kanału wykonanego wzdłuż osi jezdni

The paper presents an analysis of a flexible road pavement with a concrete pipeline running along the road axis, just under the pavement. The subgrade of such a pavement cannot be regarded as homogenous and the design cannot be limited to merely the selection of a catalogue pavement structure or to the direct application of the mechanistic-empirical method. Additional analyses are necessary in order to evaluate whether the proposed road design will provide proper protection for the underground structures located in the subgrade. The problem is considered as three-dimensional and the analyses are carried out using the finite element method. The proposed design variants are evaluated and the solution recommended for considered case is indicated. Moreover, the results of parametric analyses of the selected variant, carried out to determine the influence of the backfill parameters on the deformation of the geosynthetic reinforcement in the road foundation and on the tensile stresses in the concrete pipe, are presented.

A Simple Model to Estimate the Increase in Pavement Life Due to the Traffic Wander for Application in Connected and Autonomous Vehicles

The primary purpose of this paper is to investigate the impact of traffic wander on road pavement life for application in connected and autonomous vehicles. Research shows that in autonomous vehicles, drivers often follow the same path, leading to significant pavement damage on specific, well-defined paths. The paper examined the impact of traffic wander on pavement life by analysing two different wander distributions: normal and uniform. Based on the estimated pavement life for various pavement structures, a model that predicts the increase in pavement life due to traffic wander was developed for cracking and rutting prediction. The result of the research is the determination of relative pavement life influence functions, in which the variables are the traffic wander, asphalt layer thickness and subgrade stiffness. The obtained equations can be easily implemented for pavement service life extension evaluation. The model was also used to estimate the asphalt layer thickness as a function of the traffic expressed in terms of Equivalent Single Axle Load (ESALs). An analysis of the implications of the lateral distribution of traffic on the pavement thickness was presented. Significant reductions in the asphalt layer thickness of the pavement are achieved when wander is considered.

On modelling of the buckling resistance of welded I-section columns

This paper analyzes the influence of geometrical and material imperfections on the buckling resistance of welded I-section columns subjected to axial compression through numerical and analytical models. The paper is divided into two parts. The first part recalls a FEM parametric study of members under compression taking into account different slenderness ratios, as well as different amplitudes of initial crookedness and different values of postwelding residual stresses. The formulation of analytical approach is the main issue of the second part of the paper. Analytical formulation of the buckling resistance is based on a statistical hypothesis of the minima value approach, called the Marchant-Rankine’s-Murzewski approach (M-R-M). Calibration of imperfection factors included in the analytical formulation is made using the results of FEM simulations performed in the first stage of research investigations.

Symulacja MES obróbki cieplnej wyrobów stalowych z uwzględnieniem zjawisk termometalurgicznych. Cz. 1. Nieustalony przepływ ciepła i przejścia fazowe

Application of digital image correlation system for analysis of local plastic instabilities of perforated thin-walled bars

In the presented paper the local instabilities occurring in compression test of perforated thin-walled bars of low slenderness are observed using digital image correlation system ARAMIS. The tested samples slenderness is so low, that from theoretical point of view we are dealing with compression tests of some perforated shells. The samples are made from typical low carbon steel, which has to be treated as elasto-plastic material. Because of that, the final geometry of the sample (after unloading) is also analysed giving a good data for calibration of the theory of elasto-plasticity for large deformations. In analysed cases the total strain values are not exceptionally large, while local rotation (and permanent deformations) have significant values.

05.33: LTB resistance of rolled I-section beams: FEM verification of Eurocode's buckling curve formulation

This paper attempts to verify the Eurocode's buckling resistance criteria in case of rolled I‐ and H‐sections in monoaxial bending about their major axis using finite element simulations and two imperfection modelling techniques, namely a) using the equivalent geometric imperfection concept in which the effect of material and geometrical imperfections is represented by an equivalent minor axis bow amplitude and the lowest eigenmode imperfection profile, and b) the separate inclusion of material and geometrical imperfections. In the latter approach, material imperfections are based on the standard rolled residual stress patterns consisting of compression/tension peak values dependent upon the h / b ratio. Moreover, the geometric imperfections are included as the tolerance limit of steel I‐section rolled products. Common and higher grades of steel products are considered. The finite element shell model is utilized and built within the ABAQUS software. The Eurocode's resistance criteria are verified by using the results of FEM simulations. An impact of the moment gradient on the member buckling resistance as well as the plateau limit evaluation and the resistance increase as a result of large twist rotations accounted for are assessed. Remarks in relation to analytical formulations presented in Eurocode 3 are drawn.

Verification of the Thin-walled Beam Theory with Application of FEM and Shell Modelling

This article presents the results of a systematic comparison of predictions of the thin-walled beam theory and shell theory in the context of bending of elastic thin-walled beams with an open or closed cross-section. The results for shell theory were obtained using FEM and the ABAQUS/Standard program. The bending task of the thin-walled beam was decomposed into the task with a symmetrical and anti-symmetrical loading, so that the bending and torsion of the thin-walled element would be better visible. In order to objectify the comparison, two coefficients characterizing the mutual similarity of functions were introduced: root mean square deviation coefficient determined for the selected cross-section (in relation to the entire contour) and a coefficient determining the maximum relative difference of a given quantity. The comparison was made for both the stress and the displacement state.

The Material Anisotropy Influence on Modelling of Rutting Test with Application of Linear Viscoelasticity Constitutive Equations

In the paper a general approach to modelling of anisotropic linear viscoelastic material properties is presented. Rychlewski's (1983) spectral decomposition theorem is used and one dimensional relaxation functions of linear viscoelasticity model is adopted to eigenvalues of stiffness tensor and named Kelvin relaxation functions. Proposed model was implemented in the FEM system Abaqus on the example of transversely isotropic and isotropic material. On the basis of experimental data available in literature, models were calibrated and verified. Constitutive relations were used in the complex boundary value problem modelling standard rutting test used in road sector to assess the resistance of asphalt mixtures to rutting.

Analiza statyczna dyblowanej betonowej nawierzchni lotniskowej z uwzględnieniem zjawiska curlingu płyt

The subject of this paper is the structural analysis of a concrete airfield pavement with doweled joints after curling focusing on the doweled joints behaviour. The paper presents some examples of such pavement structures and dowel bar installation. Attention is paid to the effects of curling of slabs due to the temperature gradient across the slab thickness. It can result in the development of cracks at edges and corners of the slabs. A global structural analysis was carried out for a concrete airfield pavement exposed to extreme loading after curling. Aircraft wheel loading was considered in the analysis. The calculations of the doweled joints were parameterized based on the slab thickness and dowel diameter. The finite element method analysis was carried out using the ABAQUS/Standard software package.

Zastosowanie systemu LabVIEW do przygotowania stanowisk dydaktycznych w laboratorium Wytrzymałości Materiałów

No abstract is provided for this article.