2018 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2018

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Numerical analysis of pile installation effects in cohesive soils
- Jakub Konkol
2018 Pełny tekst
In this thesis the empirical equation for radial effective stress calculation after displacement pile installation and following consolidation phase has been proposed. The equation is based on the numerical studies performed with Updated Lagrangian, Arbitrary Lagrangian-Eulerian and Coupled Eulerian-Lagrangian formulations as well as the calibration procedure with database containing world-wide 30 pile static loading tests in cohesive soils. The empirical formula has been validated with 10 pile static load tests performed in Poznań clay and its reliability has been compared with 7 pile design methods. In this thesis, the description of research methodology and brief review of Finite Element Method with emphasis on large deformation formulations have been given. The key soil parameters which influence the radial stresses after pile installation and subsoil consolidation, both modelled numerically, have been identified. Next, the numerical methods have been validated with a high quality instrumented pile installation test in London clay and simulations of CPT and CPT-u soundings in Koszalin and Poznań clays, respectively. As a consequence of numerical tests interpretation, the general form of the empirical relation for radial effective stress has been provided. This relation has been calibrated with high quality, 30 pile static load tests. Next, the reliability of pile bearing capacity prediction with the proposed empirical formula has been checked using the database of all 75 piles and reference piles in Poznań site. Besides the validation of the author's equation for radial effective stress after installation and subsequent consolidation, the numerical calculation for the reference pile in Poznań site has been carried out. Numerical calculations include large deformation analysis where all pile construction steps have been taken into account and simplified finite element model where author's empirical formula have been adopted to predict the load-settlement response of the reference pile. Finally, the limitations of the proposed formula are provided and the further possible research directions due to pile installation effects are pointed out.
NUMERICAL ANALYSIS OF SPECIES DIFFUSION AND METHANOL DECOMPOSITION IN THERMOCATALYTIC REACTOR BASED ON THE INTERMETALLIC PHASE OF Ni3Al FOR LOW REYNOLDS NUMBERS
- Paweł Ziółkowski
- Michał Stajnke
- Paweł Jóźwik
- Zbigniew Bojar
- Piotr Ziółkowski
- Badur Janusz
2018 Pełny tekst TASK Quarterly
Numerical modelling of hydrogen production by means of methanol decomposition in a thermocatalytic reactor using corrugated foil made of the Ni3Al intermetallic phase is shown in the paper. Experimental results of the flow analysis of mixtures containing helium and methanol in a thermocatalytic reactor with microchannels were used for the initial calibration of the CFD calculations (calculations based on the Computational Fluid Dynamics method). The reaction of the thermocatalytic methanol decomposition was modelled based on experimental data, considering the size of the active surface. The drop in the methanol concentration at the inlet to the reactor, ten millimetres in front of the thermocatalytic region, is associated with the diffusion of streams of other components, mainly hydrogen and carbon monoxide. The commercial CFD code was expanded by User Defined Functions (UDFs) to include surface chemical reaction rates in the interphase between the fluid and the solid. Extrapolation of data by means of the implemented numerical model enabled the assessment of the minimum length of microreactor channels and prediction of the optimal dimension at the system outlet. The results obtained by means of numerical calculations were calibrated and compared with the experimental data, confirming a satisfactory consistency of the data.
Numerical Analysis of Steady Gradually Varied Flow in Open Channel Networks with Hydraulic Structures
- Wojciech Artichowicz
- Dariusz Gąsiorowski
2018 Pełny tekst
In this paper, a method for numerical analysis of steady gradually varied fl ow in channel networks with hydraulic structures is considered. For this purpose, a boundary problem for the system of ordinary differential equations consisting of energy equation and mass conservation equations is formulated. The boundary problem is solved using fi nite difference technique which leads to the system of non-linear algebraic equations. The arising system is solved with modi fi ed Picard method. The presented methodology is applicable to any channel network type and any type of hydraulic structure.
Numerical and Analytical Investigation of Aluminium Bracket Strengthening
- Andrzej Ambroziak
- Maciej Tomasz Solarczyk
- Antoni Biegus
2018 Pełny tekst Archives of Civil Engineering
This paper focuses on an analytical and numerical investigation of aluminium brackets used to fasten light-weight curtain walls to building facilities. The authors propose a solution to increase the load capacity of aluminium brackets by means of additional cover plates (straps). This paper also includes a short survey of literature and material properties concerning the EN AW-6060 T6 aluminium alloy. This paper suggests an initiation of a comprehensive investigation on aluminium brackets.
Numerical assessment of ultimate strength of severe corroded stiﬀened plates
- Krzysztof Wołoszyk
- Maciej Kahsin
- Yordan Garbatov
2018 Pełny tekst ENGINEERING STRUCTURES
The objective of this work is to investigate numerically (using the non-linear FEM and the approach stipulated by the Common Structural Rules) the severe nonuniform corrosion degradation eﬀect on the ultimate strength of stiﬀened plates and compare the results to the already published experimental works. Diﬀerent factors governing structural behavior of corroded stiﬀened plates are investigated, such as corrosion degradation level, material properties, initial imperfections and boundary conditions. The numerically estimated ultimate strength demonstrated to be very close to those observed during the experimental test. A sensitivity analysis with respect to the most important governing parameters of the numerical estimation of the ultimate strength is also performed and several conclusions are derived. The applied calculation procedure avoids using of a pitted surface of the corroded plates and instead of that an equivalent thickness is applying leading to a relatively fast and practical approach for ultimate trength assessment of corroded stiﬀened plates.
Numerical investigation on dynamic performance of a multi-storey steel structure model and comparison with experimental results
- Tomasz Falborski
- Barbara Sołtysik
- Robert Jankowski
2018
Shaking table testing is the most commonly adopted method to simulate earthquake forces. This approach allows us to analyze the dynamic performance and provides a valuable insight into the dynamics of building structures, which helps to improve their future safety and reliability. The present study aims to conduct a numerical evaluation of dynamic response of a multi-storey steel structure model, which was previously examined during an extensive shaking table investigation. The experimental model was subjected to a number of different earthquake ground motions and a mining tremor. In order to perform this numerical research, the analyzed two-storey steel structure model was considered as a 2-DOF system with lumped parameters, which were determined by conducting free vibra-tion tests. The results obtained demonstrate that not only seismic excitations but also mining tremors may considerably deteriorate structural behaviour by induct-ing strong structural vibrations. The time-acceleration history plots computed for the multi-storey structure model idealized as a 2-DOF system are consistent with those recorded during the previously conducted shaking table investigation, which confirms high accuracy in assuming lumped parameters to characterize the analyzed two-storey steel structure model.
Numerical Investigation on Dynamic Performance of a Multi-storey Steel Structure Model and Comparison with Experimental Results
- Tomasz Falborski
- Barbara Sołtysik
- Robert Jankowski
2018
Shaking table testing is the most commonly adopted method to simulate earthquake forces. This approach allows us to analyze the dynamic performance and provides a valuable insight into the dynamics of building structures, which helps to improve their future safety and reliability. The present study aims to conduct a numerical evaluation of dynamic response of a multi-storey steel structure model, which was previously examined during an extensive shaking table investigation. The experimental model was subjected to a number of different earthquake ground motions and a mining tremor. In order to perform this numerical research, the analyzed two-storey steel structure model was considered as a 2-DOF system with lumped parameters, which were determined by conducting free vibration tests. The results obtained demonstrate that not only seismic excitations but also mining tremors may considerably deteriorate structural behaviour by inducting strong structural vibrations. The time-acceleration history plots computed for the multi-storey structure model idealized as a 2-DOF system are consistent with those recorded during the previously conducted shaking table investigation, which confirms high accuracy in assuming lumped parameters to characterize the analyzed two-storey steel structure model.
Numerical investigations on early indicators of fracture in concrete at meso-scale.
- Michał Nitka
- Andrzej Tejchman-Konarzewski
2018
Fracture is a major reason of the global failure of concretes. The understanding of fracture is important to ensure the safety of structures and to optimize the material behaviour. In particular an early prediction possibility of fracture in concretes is of major importance. In this paper, concrete fracture under bending was numerically analysed using the Discrete Element Method (DEM). The real mesoscopic structure of a concrete beam was modelled based on μCT images. The calculations were performed under 2D and 3D conditions. The special attention was laid on the evolution of a macro-crack and different micro-structural phenomena during fracture before macro-cracking.
NUMERICAL MODEL OF PLASTIC DESTRUCTION OF THICK STEEL STRUCTURAL ELEMENTS
- Jakub Kowalski
- Janusz Kozak
2018 Pełny tekst Polish Maritime Research
In the shipbuilding industry, the risk of brittle fracture of the structure is limited by using certified materials with specified impact strength, determined by the Charpy method (for a given design temperature) and by supervising the welding processes (technology qualification, production supervision, non-destructive testing). For off-shore constructions, classical shipbuilding requirements may not be sufficient. Therefore, the regulations used in the construction of offshore structures require CTOD tests for steel and welded joints with a thickness greater than 40 mm in the case of high strength steel and more than 50 mm in the case of other steels. Classification societies do not accept CTOD test results of samples with a thickness less than the material tested. For this reason, the problem of theoretical modeling of steel structure destruction process is a key issue, because laboratory tests for elements with high thickness (in the order of 100 mm and more) with a notch are expensive (large samples, difficulties in notching), and often create implementation difficulties due to required high load and range of recorded parameters. The publication will show results and conclusions from numerical modeling of elastic properties for steel typical for offshore applications.
Numerical Modeling of Water and Ice Dynamics for Analysis of Flow Around the Kiezmark Bridge Piers
- Michał Szydłowski
- Tomasz Kolerski
2018 GeoPlanet: Earth and Planetary Sciences
This paper presents the results of a numerical model study on the effect of ice on the proposed bridge piers in the Vistula River outlet and its effect on flow conditions in the river. The model DynaRICE is used in this study, which is a two-dimensional hydro-ice dynamic numerical model developed for dynamic ice transport and jamming in rivers. To simulate river hydrodynamics in the vicinity of the bridge piers, 2-dimensional numerical model basing on finite volume technique was also used. Simulation results indicated notable effect of new structure on water and ice flow pattern. Ice forces on structures were also determined, but the load was not considerably high.
NUMERICAL MODELLING AND EXPERIMENTATION OF HISTORICAL CARPENTRY CORNER LOG JOINTS
- Anna Pestka
- Katarzyna Szepietowska
- Paweł Kłosowski
- Marcin Krajewski
- Izabela Lubowiecka
2018
The main purpose of this research is to determine the stress distributions on the contact surfaces between the logs of the historical carpentry corner joints. The additional purpose is to compare the stress distribution for four different boundary conditions in the case of dry and wet pine wood. The paper presents the results of numerical analysis of the shortcorner dovetail connection and the saddle notch corner joint, which are in common use in currently preserved objects of wooden architecture. The wood has been modelled as an orthotropic material. The numerical calculations have been carried out using MSC.Marc/Mentat software. The knowledge about the damage zones in the connections is immensely important, due to the need for maintenance, renovation and the reinforcement of existing elements in many timber historic buildings.
Numerical simulation of asphalt mixtures fracture using continuum models
- Cezary Szydłowski
- Jarosław Górski
- Marcin Stienss
- Łukasz Smakosz
2018 Pełny tekst
The paper considers numerical models of fracture processes of semi-circular asphalt mixture specimens subjected to three-point bending. Parameter calibration of the asphalt mixture constitutive models requires advanced, complex experimental test procedures. The highly non-homogeneous material is numerically modelled by a quasicontinuum model. The computational parameters are averaged data of the components, i.e. asphalt, aggregate and the air voids composing the material. The model directly captures random nature of material parameters and aggregate distribution in specimens. Initial results of the analysis are presented here.
Numerical simulation of hardening of concrete plate
- Aleksandra Kuryłowicz-Cudowska
- Jacek Chróścielewski
- Krzysztof Wilde
2018
The paper presents a theoretical formulation of concrete curing in order to predict temperature evolution and strength development. The model of heat flow is based on a well-known Fourier equation. The numerical solution is implemented by means of the Finite Difference Method. In order to verify the model, the in situ temperature measurements at the top plate of a road bridge were carried out. A high agreement between numerical and experimental data has been achieved. The results allowed to perform extended analysis of boundary conditions changes on the process of heat flow in the concrete slab. Three examples of the boundary conditions are presented and discussed.
Numerical simulation of the influence of the selected factors on the performance of a concrete road barrier H2/W5/B
- Łukasz Pachocki
- Krzysztof Wilde
2018 Pełny tekst MATEC Web of Conferences
This paper discuss the influence of selected factors on the performance of a concrete road barrier H2/W5/B. Modelling techniques of a concrete road safety system were briefly discussed. Comparison to the full scale crash test results has been shown. The concrete road safety barrier has been investigated for evaluation of the overall damage after collision under various initial conditions. The failure assessment criterion has been proposed and it was derived from a qualitative comparison of the numerical results with the full scale crash test data. Impact severity indexes have been calculated and discussed.
Numerical studies on the influence of selected construction features and road conditions on the performance of road cable barriers
- Dawid Bruski
- Wojciech Witkowski
2018
Cable barriers are commonly used on Polish roads, including motorways and local roads. Their main elements are pre-stressed wire ropes, which are usually anchored at two ends in concrete blocks buried in the soil. In this work numerical studies concerning the influence of selected construction features and parameters of the vehicle motion on the performance of cable barriers were performed. Numerical simulations are a useful tool to conduct such analyses that is now being used more and more. The calculations were carried out by using finite element code of LS-DYNA.
Numerical Study of Turbulent Flow and Heat Transfer of Nanofluids in Pipes
- Hendrik Boertz
- Albert Baars
- Janusz Cieśliński
- Sławomir Smoleń
2018 Pełny tekst HEAT TRANSFER ENGINEERING
In this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (Reynolds number between 6000 and 12000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid with particle volume concentrations ranging from 0% to 10%. Nusselt number predictions for the nanofluid are in agreement with experimental results and a conventional single-phase correlation. The mean deviation is in the range of 5%. Friction factor values show a mean deviation of 1.5% to a conventional single-phase correlation, however, they differ considerably from the nanofluid experimental data. The results indicate that the nanofluid requires more pumping power than the base fluid for high particle concentrations and Reynolds numbers on the basis of equal heat transfer rate.
Numerical Test for Stability Evaluation of Discrete-Time Systems
- Lukasz Grzymkowski
- Tomasz Stefański
2018
In this paper, a new numerical test for stability evaluation of discrete-time systems is presented. It is based on modern root-finding techniques at the complex plane employing the Delaunay triangulation and Cauchy's Argument Principle. The method evaluates if a system is stable and returns possible values and multiplicities of unstable zeros of the characteristic equation. For state-space discrete-time models, the developed test evaluates complex function related to the characteristic equation on the complex plane, so it does not require computation of state-matrix eigenvalues. The proposed method is general as it allows to analyze systems whose characteristic equations are not only polynomials. The verification of the algorithm is presented in benchmarks for both integer- and fractional-order systems.
O możliwości spawania elementów kształtowych giętych na zimno ze stali typu S355
- Wojciech Kiełczyński
2018
Celem pracy jest ocena wpływu gięcia na zimno profili na własności spoin usytuowanych w rejonie gięcia. Praca obejmuje opis tych zagadnień z punktu widzenia budowy strukturalnej i warunków sprzyjających procesowi starzenia jak i technologii spawania w odniesieniu do stali S355. Własności mechaniczne elementów giętych na zimno są niehomogeniczne wzdłuż obwodu z powodu różnic w umocnieniu powstającego w trakcie gięcia na zimno. w przypadku spawania w narożach giętych na zimno kształtowników należy przestrzegać następujących zasad.: 1. Materiał spawany winien być dobrej jakości i o dużej czystości metalurgicznej.Wymagania te spełniają stale uspokojone. Nie należy stosować stali półuspokojonej lub nieuspokojonej. Stale winny zawierać dodatek Al. i Ti. Zwiększenie odporności stali na starzenie zapewnia dodatek aluminium wprowadzony podczas wytopu, który wiąże azot (zawartość 0,02% Al, gwarantuje całkowite związanie azotu w sposób trwały, tworząc azotki AlN) Al. ponadto jest bardzo dobrym odtleniaczem). 2. Należy dopuszczać do spawania stale o niskiej zawartości azotu N≤0,01%, Azot jest głównym promotorem procesu starzenia. 3. Proces spawania należy prowadzić w taki sposób, aby w strefie wpływu ciepła (SWC), oraz w spoinie nie generowały się obszary o twardości powyżej 350HV.
O obliczeniach płyt fundamentowych
- Andrzej Ambroziak
- Krzysztof Górski
2018 Pełny tekst Przegląd Budowlany
W pracy przedstawiono analizę sposobu przylożenia obciążenia na wyniki wymiarowania zbrojenia w płycie fundamentowej. Dodatkowo autorzy dokonali krótkiego przeglądu literatury z zakresu płyt fundamentowych.
O projektowaniu ściany szczelinowej
- Andrzej Ambroziak
- Wojciech Moroz
2018 Przegląd Budowlany
W pracy przedstawiono proces weryfikacji i porównania obliczeń otrzymanych z programu bazującego na metodzie elementów skończonych z wynikami analitycznymi dla analizowanej ściany szczelinowej z przyporą ziemną. Dodatkowo autorzy dokonali krótkiego przeglądu literatury z zakresu ścian szczelinowych.