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wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: NON-LOCAL THEORY REINFORCED CONCRETE, CRACK BAND APPROACH
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Crack Resistance of Asphalt Concrete Subjected to Environmental Factors
PublikacjaThe paper presents an analysis of the influence of environmental factors on the cracking susceptibility of asphalt concrete resulting in a change in the durability of asphalt pavement. In order to assess the phenomenon, laboratory tests were carried out taking into account the destructive effects of moisture, freeze-thaw cycle and long-term ageing. The influence of both factors occurring simultaneously was also verified. Due to...
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Positive solutions to Sturm–Liouville problems with non-local boundary conditions
PublikacjaIn this paper, the existence of at least three non-negative solutions to non-local boundary-value problems for second-order differential equations with deviating arguments α and ζ is investigated. Sufficient conditions, which guarantee the existence of positive solutions, are obtained using the Avery–Peterson theorem. We discuss our problem for both advanced and delayed arguments. An example is added to illustrate the results.
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Influence of stirrups in a concrete shell on strengthening reinforced concrete column
PublikacjaTwelve concrete columns, with a 150x150mm square section and three columns with a circular section (d=200mm), are tested to investigate the effect of strengthening by RC jacket. Based on a confined concrete model for axial static loading, an analytical methods, reported in the literature are proposed to predict the behavior of columns with RC jacket. The results support the conception that the effect of strengthening depends...
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FE analysis of strain localization in concrete in elasto-plasticity and damage mechanics with non-local softening
PublikacjaW artykule przedstawiono wyniki symulacji numerycznych zjawiska lokalizacji odkształceń w betonie wykonanaych przy zastosowaniu metody elementów skończonych (MES). Do opisu betonu wykorzystano dwa prawa materiałowe zdefiniowane w ramach teorii plastyczności (kryterium Druckera-Pragera w ściskaniu i warunek Rankine'a w rozciąganiu) oraz mechaniki uszkodzeń w sformułowaniu odkształceniowym. Dla poprawnego opisu lokalizacji (regularyzacji...
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An elasto-plastic constitutive model with non-local softening and viscosity to describe dynamic concrete behaviour.
PublikacjaW artykule zaproponowano model do opisu betonu podczas dynamicznego obciążenia. Przyjęto model sprężysto-plastyczny z degradacją sztywności i nielokalnym osłabieniem rozszerzony o lepkość. Obliczenia MES dla elementów betonowych pod obciążeniem dynamicznym o różnej prędkości obciążenia porównano z doświadczeniami.
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Regularized Local Basis Function Approach to Identification of Nonstationary Processes
PublikacjaThe problem of identification of nonstationary stochastic processes (systems or signals) is considered and a new class of identification algorithms, combining the basis functions approach with local estimation technique, is described. Unlike the classical basis function estimation schemes, the proposed regularized local basis function estimators are not used to obtain interval approximations of the parameter trajectory, but provide...
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Exact resultant equilibrium conditions in the non-linear theory of branching and self-intersecting shells
PublikacjaWe formulate the exact, resultant equilibrium conditions for the non-linear theory of branching and self-intersecting shells. The conditions are derived by performing direct through-the-thickness integration in the global equilibrium conditions of continuum mechanics. At each regular internal and boundary point of the base surface our exact, local equilibrium equations and dynamic boundary conditions are equivalent, as expected,...
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Local variance factors in deformation analysis of non-homogenous monitoring networks
PublikacjaThis paper proposes a modification of the classical deformation analysis algorithm for non-homogeneous (e.g. linear-angular) monitoring networks. The basis for the proposed solution is the idea of local variance factors. The theoretical discussion was complemented with an example of its application on a simulated horizontal monitoring network. The obtained results confirm the usefulness of the proposed solution.
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3-D finite-difference time-domain modelling of ground penetrating radar for identification of rebars in complex reinforced concrete structures
PublikacjaThis paper presents numerical and experimental investigations to identify reinforcing bars using the ground penetrating radar (GPR) method. A novel element of the paper is the inspection of different arrangements of reinforcement bars. Two particular problems, i.e. detection of few adjacent transverse bars and detection of a longitudinal bar located over or under transverse reinforcement, have been raised. An attention was also...
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Analytical predictions for the buckling of a nanoplate subjected to non-uniform compression based on the four-variable plate theory
PublikacjaIn the present study, the buckling analysis of the rectangular nanoplate under biaxial non-uniform compression using the modified couple stress continuum theory with various boundary conditions has been considered. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations have been obtained using the Hamilton’s principle. An analytical approach has been applied to obtain...
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Seismic probabilistic assessment of steel and reinforced concrete structures including earthquake-induced pounding
PublikacjaRecent earthquakes demonstrate that prioritizing the retrofitting of buildings should be of the utmost importance for enhancing the seismic resilience and structural integrity of urban structures. To have a realistic results of the pounding effects in modeling process of retrofitting buildings, the present research provides seismic Probability Factors (PFs), which can be used for estimating collision effects without engaging in...
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Model-Based Adaptive Machine Learning Approach in Concrete Mix Design
PublikacjaConcrete mix design is one of the most critical issues in concrete technology. This process aims to create a concrete mix which helps deliver concrete with desired features and quality. Contemporary requirements for concrete concern not only its structural properties, but also increasingly its production process and environmental friendliness, forcing concrete producers to use both chemically and technologically complex concrete...
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Machine learning-based seismic response and performance assessment of reinforced concrete buildings
PublikacjaComplexity and unpredictability nature of earthquakes makes them unique external loads that there is no unique formula used for the prediction of seismic responses. Hence, this research aims to implement the most well-known Machine Learning (ML) methods in Python software to propose a prediction model for seismic response and performance assessment of Reinforced Concrete Moment-Resisting Frames (RC MRFs). To prepare 92,400 data...
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Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-002)
Dane BadawczeThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
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Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-Con)
Dane BadawczeThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
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Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-004)
Dane BadawczeThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
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Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-006)
Dane BadawczeThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
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FE-analysis of the beaviour of concrete elements with coupled elasto-plastic-damage models with non-local softening
PublikacjaArtykuł omawia wyniki symulacji zachowania sie elementów betonowych poddanych cyklicznemu obciążeniu. Do symulacji zastosowano połączone modele sprężysto-plastyczne z degradacją sztywności i z nielokalnym osłabieniem. Wyniki symulacji porównano z doswiadczeniami.
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FE-modelling of concrete behaviour under mixed mode conditions with non-local and cohesive constitutive models.
PublikacjaW artykule przedstawiono wyniki symulacji rys zaokrąglonych w elementach betonowych w warunkach mieszanego sposobu obciążenia. Symulacje wykonano przy zastosowaniu modelu rys kohezyjnych i modeli mechaniki ośrodka ciągłego z nielokalnym osłabieniem.. Wyniki symulacji porównano z doświadczeniami.
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Analysis of concrete behaviour under cycling within coupled elasto-plastic-damage with non-local softening
PublikacjaArtykuł omawia wyniki symulacji zachowania sie elementów betonowych poddanych cyklicznemu obciążeniu. Do symulacji zastosowano 3 połączone modele sprężysto-plastyczne z degradacją sztywności i z nielokalnym osłabieniem. Wyniki symulacji porównano z doświadczeniami laboratoryjnymi..
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Machine learning-based seismic fragility and seismic vulnerability assessment of reinforced concrete structures
PublikacjaMany studies have been performed to put quantifying uncertainties into the seismic risk assessment of reinforced concrete (RC) buildings. This paper provides a risk-assessment support tool for purpose of retrofitting and potential design strategies of RC buildings. Machine Learning (ML) algorithms were developed in Python software by innovative methods of hyperparameter optimization, such as halving search, grid search, random...
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Data-driven Models for Predicting Compressive Strength of 3D-printed Fiber-Reinforced Concrete using Interpretable Machine Learning Algorithms
Publikacja3D printing technology is growing swiftly in the construction sector due to its numerous benefits, such as intricate designs, quicker construction, waste reduction, environmental friendliness, cost savings, and enhanced safety. Nevertheless, optimizing the concrete mix for 3D printing is a challenging task due to the numerous factors involved, requiring extensive experimentation. Therefore, this study used three machine learning...
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Minimal transverse reinforcement of reinforced concrete members
PublikacjaW pierwszej części pracy omówiono zagadnienia dotyczące minimalnego zbrojenia na ścinanie elementów żelbetowych w kontekście norm europejskich oraz pozaeuropejskich. W drugiej części pracy dokonano analizy wyników badań eksperymentalnych dotyczących nośności elementów bez zbrojenia poprzecznego, które stanowią podstawę do weryfikacji zaleceń normowych w zakresie minimalnego zbrojenia na ścinanie.
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Flow cytometric approach to evaluate the impact of hydro-technical concrete compounds’ release to the freshwater microbiome
PublikacjaThe aim of this research was to test the potential of applying a flow cytometric procedure to evaluate the impact of concrete compounds’ release to the freshwater microbiome. Cells from the collected samples were stained with a fluorogenic redox indicator dye that measures the redox potential of microbial cells. This novel approach was combined with the assessment of microorganisms’ penetration into the internal structures of concrete...
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Chained machine learning model for predicting load capacity and ductility of steel fiber–reinforced concrete beams
PublikacjaOne of the main issues associated with steel fiber–reinforced concrete (SFRC) beams is the ability to anticipate their flexural response. With a comprehensive grid search, several stacked models (i.e., chained, parallel) consisting of various machine learning (ML) algorithms and artificial neural networks (ANNs) were developed to predict the flexural response of SFRC beams. The flexural performance of SFRC beams under bending was...
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A study on microcrack monitoring in concrete: discrete element method simulations of acoustic emission for non-destructive diagnostics
PublikacjaThe research is focused on the monitoring of fracture evolution in concrete beams under three-point bending using the acoustic emission technique and the discrete element method. The main objective of the study was to numerically and experimentally investigate the mechanism behind the generation of elastic waves during acoustic emission events and their interaction with micro- and macro-cracking in concrete beams under monotonic...
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Concrete beams under bending - calculations of size effects within stochastic elasto-plasticity with non-local softening
PublikacjaW artykule przedstawiono wyniki numerycznej analizy efektów skali (efektu deterministycznego i stochastycznego) w belkach betonowych nacięciem poddanych zginaniu z uwzględnieniem lokalizacji odkształceń. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i sprężysto-plastycznego modelu z nielokalnym osłabieniem. Pokazano wpływ wielkości belek betonowych na nośność.
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Coupled elasto-plastic-damage model with non-local softening enhanced by viscosity to describe dynamic concrete behaviour
PublikacjaW artykule zaproponowano model do opisu betonu podczas dynamicznego obciążenia. Przyjęto model sprężysto-plastyczny z degradacją sztywności i nielokalnym osłabieniem rozszerzony o lepkość. Obliczenia MES dla elementów betonowych pod obciążeniem dynamicznym o różnej prędkości obciążenia porównano z doświadczeniami.
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Mesoscopic simulations of a fracture process in reinforced concrete beam in bending using a 2D coupled DEM/micro-CT approach
PublikacjaW tej pracy zbadano numerycznie w warunkach 2D złożony proces pękania w krótkiej prostokątnej belce betonowej wzmocnionej jednym prętem podłużnym (bez zbrojenia pionowego) i poddanej quasi-statycznemu zginaniu w trzech punktach. Krytyczne pęknięcie poprzeczne w belce spowodowało jej uszkodzenie podczas doświadczenia. Symulacje numeryczne przeprowadzono klasyczną metodą elementów dyskretnych (DEM). Przyjęto trójfazowy opis betonu:...
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Shear fracture of longitudinally reinforced concrete beams under bending using Digital Image Correlation and FE simulations with concrete micro-structure based on X-ray micro-computed tomography images
PublikacjaThe paper presents experimental and numerical investigations of the shear fracture in rectangular concrete beams longitudinally reinforced with steel or basalt bar under quasi-static three point bending. Shear fracture process zone formation and development on the surface of beams was investigated by Digital Image Correlation (DIC) whereas thorough analyses of 3D material micro-structure, air voids, width and curvature of shear...
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Evaluation of pounding effects between reinforced concrete frames subjected to far-field earthquakes in terms of damage index
PublikacjaIn this paper, three different damage indexes were used to detect nonlinear damages in two adjacent Reinforced Concrete (RC) structures considering pounding effects. 2-, 4- and 8-story benchmark RC Moment Resisting Frames (MRFs) were selected for this purpose with 60%, 75%, and 100% of minimum separation distance and also without any in-between separation gap. These structures were analyzed using the incremental dynamic analysis...
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Non-Destructive Diagnostics of Concrete Beams Strengthened with Steel Plates Using Modal Analysis and Wavelet Transform
PublikacjaExternally bonded reinforcements are commonly and widely used in civil engineering objects made of concrete to increase the structure load capacity or to minimize the negative effects of long-term operation and possible defects. The quality of adhesive bonding between a strengthened structure and steel or composite elements is essential for effective reinforcement; therefore, there is a need for non-destructive diagnostics of adhesive...
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Parameter estimation of a discrete model of a reinforced concrete slab
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3D DEM simulations of fracture in reinforced concrete beams
PublikacjaArtykuł dotyczy zachowania się belki żelbetowej bez zbrojenia pionowego przy trzypunktowym zginaniu. Belka uległa zniszczeniu wskutek ścinania z powodu obecności nadmiernego zbrojenia podłużnego. Eksperymenty przeprowadzono w skali laboratoryjnej z wykorzystaniem systemu mikro-CT, a następnie odtworzono je w analizach numerycznych stosując metodą elementów dyskretnych 3D (DEM). Zastosowano 4-fazowy model betonu z mezostrukturą,...
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Drilling couples and refined constitutive equations in the resultant geometrically non-linear theory of elastic shells
PublikacjaIt is well known that distribution of displacements through the shell thickness is non-linear, in general. We introduce a modified polar decomposition of shell deformation gradient and a vector of deviation from the linear displacement distribution. When strains are assumed to be small, this allows one to propose an explicit definition of the drilling couples which is proportional to tangential components of the deviation vector....
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Dynamic modeling of non-cylindrical curved viscoelastic single-walled carbon nanotubes based on the second gradient theory
PublikacjaThis paper is devoted to the theoretical study of the dynamic response of non-cylindrical curved viscoelastic single-walled carbon nanotubes (SWCNTs). The curved nanotubes are largely used in many engineering applications, but it is challenging in understanding mechanically the dynamic response of these curved SWCNTs when considering the influences of the material viscosity. The viscoelastic damping effect on the dynamic response...
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Computational simulations of concrete behaviour under dynamic conditions using elasto-visco-plastic model with non-local softening
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Notched concrete beams under bending - calculations of size effects within stochastic elasto-plasticity with non-local softening
PublikacjaW artykule przedstawiono wyniki numerycznej analizy efektów skali (efektu deterministycznego i stochastycznego) w belkach betonowych nacięciem poddanych zginaniu z uwzględnieniem lokalizacji odkształceń. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i sprężysto-plastycznego modelu z nielokalnym osłabieniem. Pokazano wpływ wielkości belek na nośność z uwzględnieniem stochastycznego rozkładu wytrzymałości na...
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Computational simulations of concrete behaviour under dynamic conditions using elasto-visco-plastic model with non-local softening.
PublikacjaW artykule przedstawiono wyniki obliczeniowych symulacji zachowania betonu w warunkach dynamicznych stosując sprężysto-lepko-plastyczny model z nielokalnym osłabieniem. Wykonano obliczenia dla ściskania jednoosiowego, rozciągania jednoosiowego i zginania. Dla dużych prędkości obciążenia uwzględniono fragmentację materiału. Wyniki porównano z doswiadczeniami.
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Identification of Quasi-Periodically Varying Systems Using the Local Basis Function Approach
PublikacjaIn this paper we propose a solution to the problem of tracking quasi-periodically varying systems based on the local basis function (LBF) approach. Within this framework, parameter trajectories are locally approximated using linear combinations of specific functions of time known as basis functions. We derive both bias and variance characteristics of LBF estimators. Additionally, we demonstrate that the computational burden associated...
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Linear game non-contextuality and Bell inequalities—a graph-theoretic approach
PublikacjaWe study the classical and quantum values of a class of one-and two-party unique games, that generalizes the well-known XOR games to the case of non-binary outcomes. In the bipartite case the generalized XOR(XOR-d) games we study are a subclass of the well-known linear games. We introduce a 'constraint graph' associated to such a game, with the constraints defining the game represented by an edge-coloring of the graph. We use the...
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Introduction to Local Governance and Theory of Spatial Planning (2021/22, winter semester)
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Local buckling and initial post-buckling behaviour of channel member flange - analytical approach
PublikacjaThe local buckling and initial post-buckling behaviour of the cold-formed channel member flange is investigated. The governing nonlinear differential equation for axially compressed columns and beams undergoing pure bending is derived using the stationary total potential energy principle. The critical stress and initial post-buckling equilibrium path is determined by means of a perturbation approach. The results obtained allow...
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FE analysis of reinforced concrete corbels with enhanced continuum models
PublikacjaW artykule pokazano wyniki MES symulacji wsporników żelbetowych. Zachowanie wsporników modelowano przy zastosowaniu 3 różnych modeli betonu: sprężysto-plastycznego, degradacji sprężystej i rozmytych rys. Modele rozszerzono o długość mikrostruktury przy zastosowaniu teorii nielokalnej. Wyniki numeryczne porównano z doświadczeniami z literatury.
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Optimization-based stacked machine-learning method for seismic probability and risk assessment of reinforced concrete shear walls
PublikacjaEfficient seismic risk assessment aids decision-makers in formulating citywide risk mitigation plans, providing insights into building performance and retrofitting costs. The complexity of modeling, analysis, and post-processing of the results makes it hard to fast-track the seismic probabilities, and there is a need to optimize the computational time. This research addresses seismic probability and risk assessment of reinforced...
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FE calculations of a deterministic and statistical size effect in concrete under bending within stochastic elasto-plasticity and non-local softening
PublikacjaW artykule przedstawiony wyniki obliczeń MES deterministycznego i statystycznego efektu skali w belkach betonowych podczas zginania. Zastosowano model w ramach stochastycznej sprężysto-plastyczności i nielokalnego osłabienia. Belki były geometrycznie podobne. Wyniki porównano z modelem efektu skali Bazanta.
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Airfoil Design Under Uncertainty Using Non-Intrusive Polynomial Chaos Theory and Utility Functions
PublikacjaFast and accurate airfoil design under uncertainty using non-intrusive polynomial chaos (NIPC) expansions and utility functions is proposed. The NIPC expansions provide a means to efficiently and accurately compute statistical information for a given set of input variables with associated probability distribution. Utility functions provide a way to rigorously formulate the design problem. In this work, these two methods are integrated...
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The application of non-destructive methods in the diagnostics of the approach pavement at the bridges
PublikacjaThe article presents the possibility of using non-destructive methods of road pavement diagnostics as an alternative to traditional means to assess the reasons for premature cracks adjacent to bridge objects. Two scanning methods were used: laser scanning to measure geometric surface deformation and ground penetrating radar (GPR) inspection to assess the road pavement condition. With the use of a laser scanner, an effective tool...
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A Universal Theory of Wisdom . A Mind - oriented Approach
PublikacjaThe purpose of the paper is to synthesize the issues of human wisdom in terms of minds which create knowledge-based judgment. We form a transdisciplinary, big-picture view of the wisdom of humans. Findings: Wisdom is the right judgment and choice in the context of the art of living. Practical implications: Wisdom can be developed within the set of minds. Social implications: To pursue wisdom in thinking and action, one must extend...
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Ingoing and outgoing waves in the non-relativistic theory of photoionization
PublikacjaZastosowano rachunek zaburzeń zależny od czasu do wyprowadzenia wzoru na różniczkowy przekrój czynny na fotojonizację nierelatywistycznego kwantowego układu jednoelektronowego płaską monochromatyczną falą elektromagnetyczną. Pokazano,że pochodzenie oraz asymptotykę tzw. ''funkcji falowej stanu końcowego'', wchodzącej do tego wzoru, można wytłumaczyć bez odwoływania się do kontrowersyjnej argumentacji podanej przez Breita i Bethego.