wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: NON-LOCAL THEORY REINFORCED CONCRETE, CRACK BAND APPROACH
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Experimental investigations of damage evolution in concrete during bending by continuous micro-CT scanning
PublikacjaThe paper describes experimental investigation results of fracture in notched concrete beams under quasi-static three-point bending. To visualize 3D fracture in concrete under bending, an extended X-ray micro-computed tomography system was used, i.e. the tomography system SkyScan 1173 was connected to the loading machine ISTRON 5569. This combined system enabled to shot images of deforming concrete beams during a continuous deformation...
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Remote sensing and photogrammetry techniques in diagnostics of concrete structures
PublikacjaRecently laser scanning technologies become widely used in many areas of the modern economy. In the following paper authors show a potential spectrum of use Terrestrial Laser Scanning (TLS) in diagnostics of reinforced concrete elements. Based on modes of failure analysis of reinforcement concrete beam authors describe downsides and advantages of adaptation of terrestrial laser scanning to this purpose, moreover reveal under which...
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A constitutive law for concrete with smooth transition from continuous into discontinuous cracks’ description
PublikacjaPaper presents a constitutive model for concrete that combines a continuous and discontinuous crack’s description to simulate the concrete under tensile dominated loads. In a continuum regime, two different constitutive laws were used. First, a plasticity model with the Rankine failure criterion and an associated flow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. Both model alternatives...
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Tests of bond between concrete and steel bars – literature background and program of own research
PublikacjaThis article deals with the issue of the bond between concrete and reinforcement. The bond is crucial for reinforced concrete elements because it is possible to transfer forces (stresses) from concrete to the reinforcement. Basic information related to the cooperation of concrete and rebars was recalled in the article. Selected issues concerning theoretical and numerical analysis as well as experiments of the bond phenomenon were...
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Increasing the lifetime of engineering structures through the use of composite laggings
PublikacjaThe use of composite laggings prevents concrete (chemical and biological) corrosion. Columns coated with composite or reinforced composite are more resistant to negative environmental impact on concrete or steel. The mechanical properties of the reinforced casing also cause that these types of columns are more resistant to lateral forces. The applied casing limits carbonization of concrete and cyclical freezing and thawing with...
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Shear resistance of low height precast concrete lintels
PublikacjaThe scope of the paper is to investigate analytically and determine experimentally the shear resistance of low height reinforced precast concrete lintels. The chosen procedures included in national and international standards applied for the design of structural concrete elements to an estimation of shear behaviour of reinforced concrete elements are described. The characteristic and designed shear strength of precast concrete...
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Diagnostics of pillars in St. Mary’s Church (Gdańsk, Poland) using the GPR method
PublikacjaThe main goal of this study was non-destructive evaluation of pillars in the St. Mary’s Church (Gdańsk, Poland) using the ground penetrating radar (GPR) technique. The GPR inspection was conducted on four brick masonry pillars and five pillars strengthened by reinforced concrete jacketing. Data were acquired with a 2 GHz antenna along longitudinal and transverse profiles. The study involved the estimation of the electromagnetic...
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Krzysztof Jan Kaliński prof. dr hab. inż.
OsobyUkończył studia magisterskie na Wydziale Mechanicznym Technologicznym (MT) PG (1980, dyplom z wyróżnieniem). Stopień doktora otrzymał na Wydziale Budowy Maszyn PG (1988, praca wyróżniona), stopień doktora habilitowanego na Wydziale Mechanicznym (WM) PG (2002, praca wyróżniona), a tytuł profesora nauk technicznych – w 2013 r. Od 2015 r. jest profesorem zwyczajnym, a od 2019 r. - profesorem. Obszar jego badań naukowych obejmuje:...
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Damage of a post-tensioned concrete bridge – Unwanted cracks of the girders
PublikacjaThe cracking of a post-tensioned T-beam superstructure, which was built using the incremental launching method, is analyzed in the paper. The problem is studied in detail, as specific damage was observed in the form of longitudinal cracks, especially in the mid-height zone of the girder at the interface of two assembly sections. The paper is a case study. A detailed inspection is done and non-destructive testing results of the...
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Fracture of aluminium joints bonded with epoxy adhesive reinforced by mmt nanoparticles
PublikacjaCrack propagation behavior was studied for aluminium/aluminum adhesive joints bonded with two epoxy adhesives: pure and reinforced with clay nanoparticles. The focus was also on the novel use of the constant displacement rate test to study adhesion/adhesives efficiency. The epoxy systems studied were: Epidian E6 produced from bisphenol A and epichlorohydrin, (''Organika -Sarzyna'' Poland); pure or strengthened with montmorillonit...
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Corrosion behavior of concrete produced with diatomite and zeolite exposed to chlorides
PublikacjaChloride induced reinforcement corrosion is widely accepted to be the most frequent mechanism causing premature degradation of reinforced concrete structures. The electrochemical impedance of reinforcing steel in diatomite- and zeolite-containing concrete exposed to sodium chloride was assessed. Chemical, physical and mineralogical properties of three concrete samples (20% diatomite, 20% zeolite, and a reference containing neither)...
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EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF CONCRETE BEHAVIOUR AT MESO-LEVEL DURING QUASI-STATIC SPLITTING TENSION
PublikacjaThe paper describes experimental and numerical results of quasi-static splitting tensile tests on concrete specimens at meso-scale level. The loading strip was made of plywood or steel. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: 3D x-ray micro-computed tomography, 2D scanning electron microscope and manual 2D digital microscope. The discrete element method was used to directly...
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The experimental research on RC columns, loaded at sign-variable eccentricity
PublikacjaThe research focuses on testing the behaviour of the reinforced concrete columns compressed at a variable eccentricity. The fact of possible variable eccentricity in compressed columns is not considered in the current calculation procedures. The objective of the research was to examine whether indeed the load history has no impact and whether the reinforced concrete columns compressed at eccentric of variable sign could be analysed...
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The vibration-based assessment of the influence of elevated temperature on the condition of concrete beams with pultruded GFRP reinforcement
PublikacjaConcrete beams reinforced with glass fiber reinforced polymer (GFRP) bars subjected to elevated temperature have been experimentally studied. The influence of high temperatures on GFRP-reinforced concrete beams condition has been check both, destructively and nondestructively. The nondestructive tests foresaw vibration-based tests to obtain the natural frequency values after exposure to varying temperatures. The vibration-based...
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On the crack front curvature in bonded joints
PublikacjaStandard tests of adhesively bonded specimens are likely to produce heterogeneous stress distribution along the crack front and its vicinity. High separation rate mode I dominated fracture test is performed.Observation of post mortem fractured surfaces with an optical microscope reveals characteristic features of mixed mode I/III fracture near the sides of the specimen but not in the middle. At first, finite elements calculations...
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Effect of polymer fibres reinforcement on selected properties of asphalt mixtures
PublikacjaThe paper presents selected results of the research program concerning fibre reinforced asphalt concrete. Aramid-polyalphaolefin fibres was used in this study. Selected properties responsible for low temperature cracking and resistance to permanent deformation are presented in this paper. Low temperature cracking susceptibility was evaluated with the results obtained from bending test of rectangular beams with constant rate of...
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CFGFRPT Piles with a Circular Cross-Section and their Application in Offshore Structures
PublikacjaThe possibilities of using concrete piles in a polymer composite reinforced with glass fibres in offshore facilities were shown. Laboratory tests of CFGFRPT type piles compressed axially and in eccentric compression for the analysis of CFGFRPT piles were used. Methods of analysis of dynamic systems for mathematical modelling of the displacement of the hammer in the pile driving process were applied. The possibilities of combining...
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Electron mobility variance in semiconductors: the variance approach
PublikacjaPraca przedstawia nowe podejście da analizy zjawisk losowych w półprzewodnikach. Uwzględnia kilka mechanizmów zjawisk fluktuacji ruchliwości w półprzewodnikach, prowadzących do powstawamai składowej szumów typu 1/f, dominujących w zakresie małych czetotliwości. Przedstawia analizę sposobu wyznaczenia stałej Hooge'a określającej intensywność szumów typu 1/f.The statistical non-triviality of current carrier mobility fluctuations...
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Displacements of chimney in the light of computer calculations and surveying
PublikacjaThe article presents the numerical analysis of reinforced concrete chimney displacements, which was carried out geodetic measurements.
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Discrete element method simulations of fracture in concrete under uniaxial compression based on its real internal structure
PublikacjaThe paper describes experimental and numerical results of concrete fracture under quasi-static uniaxial compression. Experimental uniaxial compression tests were performed on concrete cubic specimens. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: three-dimensional X-ray microcomputed tomography, two-dimensional scanning electron microscope and manual two-dimensional digital...
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On some problems in determining tensile parameters of concrete model from size effect tests
PublikacjaThe paper presents results of numerical simulations of size effect phenomenon in concrete specimens. The behaviour of in-plane geometrically similar notched and unnotched beams under three-point bending is investigated. In total 18 beams are analysed. Concrete beams of four different sizes and five different notch to depth ratios are simulated. Two methods are applied to describe cracks. First, an elasto-plastic constitutive law...
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On unique kinematics for the branching shells
PublikacjaWe construct the unique two-dimensional (2D) kinematics which is work-conjugate to the exact, resultant local equilibrium conditions of the non-linear theory of branching shells. Several types of junctions are described. For each type the explicit form of the principle of virtual work is derived.
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Janusz Kozak prof. dr hab. inż.
OsobyDr hab. inż. Janusz Kozak Dziekan Wydziału Oceanotechniki i Okrętownictwa Politechniki Gdańskiej Urodzony: 04.07.1953 w Pucku Absolwent Technikum Budowy Okrętów „Conradinum” w Gdańsku, 1973. Absolwent Instytutu Okrętowego PG, 1978. Po ukończeniu studiów praca w Stoczni Gdynia, a od roku 1980 w Katedrze Technologii Okrętów Instytutu Okrętowego a później Wydziału Oceanotechniki i Okrętownictwa Politechniki Gdańskiej kolejno na...
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Experimental investigations on the mechanical properties and damage detection of carbon nanotubes modified crumb rubber concrete
PublikacjaThis study presents a modified crumb rubber (MCR) concrete design mix reinforced with multi-walled carbon nanotubes (MWCNTs), mechanical characterization, and cracking monitoring using the acoustic emission (AE) technique. The results showed that the bridging effect of MWCNTs and MCR in the concrete mix mitigated the shortcomings of MWCNT-MCR concrete and improved the flexural and compressive strengths by 18.3% and 26.5%, respectively,...
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Spatial and Regional Planning Studies
Kursy OnlineThe course objective is to teach the basic, practical skills of planning for the architects. Three aspects of planning will be taught during the course: building control, regulatory planning and operational planning. The students will explore the role of planning in granting the building permissions, how to prepare the planning (zoning) regulations and finally what are urban design tools, which can be used to coordinate the development...
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Structural properties of hypothetical CeBa2Cu3O7 compound from LSDA+DMFT calculations
PublikacjaThe hypothetical stoichiometric CeBa2Cu3O7 (Ce123) compound, which has not been synthesized as a single phase yet, was studied by the density functional theory (DFT). We utilized a method which merges the local spin density approximation (LSDA) with the dynamical mean-field theory (DMFT) to account for the electronic correlations. The LSDA+DMFT calculations were performed in the high-temperature range. The particular emphasis was...
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Accuracy improvement of the prestressed concrete structures precise geometry assessment by use of bubble micro-sampling algorithm
PublikacjaPrestressed concrete structures are well-known technology for a vast period, but nevertheless, this very technology is a leading solution, currently used in construction industry. Prestressed concrete structures have a huge advantage over conventional methods because it uses the properties of concrete in a very efficient way. The main idea behind this technology is to introduce into the cross-section of the structure, the internal...
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Notch fatigue analysis and life assessment using an energy field intensity approach in 7050-T6 aluminium alloy under bending-torsion loading
PublikacjaThis paper studies the fatigue crack initiation and fatigue crack propagation of notched cylindrical bars made of 7050-T6 aluminium alloy subjected to multiaxial bending-torsion loading. The sites of crack initiation and the angles of crack initiation were successfully predicted from the distribution of the first principal stress at the notch surface. Fatigue crack initiation lives were computed through the new concept of energy...
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The experimental research on the axially compressed CFFT columns
PublikacjaThe research objectives is to test the behaviour of the axially compressed glass fiber reinforced polymer tubes CFFT (concrete-filled FRP tube) withe the R-C core.
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Lateral load resistance of piled raft foundation - A case study of District Jail, Saidu Sharif, Swat Pakistan
PublikacjaPiled raft foundations under lateral loads are usually designed as a pile group, ignoring the contribution of the raft to resisting the lateral loads. In this paper, a case study was performed to determine the raft's contribution to the lateral load resistance. This study analyzed a pile-supported reinforced concrete retaining wall for two different foundation conditions, i.e., pile group foundation and pile raft foundation. Pile group...
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GPR investigation of the strengthening system of a historic masonry tower
PublikacjaIn this paper the condition assessment of the strengthening system of a masonry tower was carried out by the GPR method. The study provided unique experimental data acquired during measurements of the reinforced concrete frame embedded in masonry walls. Conducted numerical and experimental investigations were focused on the phenomenon of the diffraction-refraction scattering of the electromagnetic energy. A hyperbola resulting...
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Towards Resource Theory of Coherence in Distributed Scenarios
PublikacjaThe search for a simple description of fundamental physical processes is an important part of quantum theory. One example for such an abstraction can be found in the distance lab paradigm: if two separated parties are connected via a classical channel, it is notoriously difficult to characterize all possible operations these parties can perform. This class of operations is widely known as local operations and classical communication....
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HYGRO-MAGNETIC VIBRATION OF THE SINGLE-WALLED CARBON NANOTUBE WITH NONLINEAR TEMPERATURE DISTRIBUTION BASED ON A MODIFIED BEAM THEORY AND NONLOCAL STRAIN GRADIENT MODEL
PublikacjaIn this study, vibration analysis of single-walled carbon nanotube (SWCNT) has been carried out by using a refined beam theory, namely one variable shear deformation beam theory. This approach has one variable lesser than a contractual shear deformation theory such as first-order shear deformation theory (FSDT) and acts like classical beam approach but with considering shear deformations. The SWCNT has been placed in an axial or...
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Simplified method of applying loads to flat slab floor structural model
PublikacjaThe article analyses the impact of the live load position on the surface of a reinforced concrete flat slab floor of 32.0 m × 28.8 m. Four variants of a live load position are investigated: located on the entire concrete slab, set in a chessboard pattern, applied by bands and imposed separately in each of the slab panels. Conclusions are drawn upon differences in bending moments, the time of calculation and the size of output files....
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SOLUTIONS OF THE INTERMEDIATE SUPPORT STRUC- TURES OF THE NORTHERN MARMARA HIGHWAY (ISTAN- BUL’S RING ROAD) IN THE CONTEXT OF SEISMIC ACTIVITY
PublikacjaIn 2014–2018, as a result of the expansion of the city of Istanbul in Turkey, a project was imple- mented consisting of building a northern ring road, called the Northern Marmara Highway. The concept of the structural design of the ring road’s intermediate supports aims at constructing sup- ports that according to the TURKISH DLH 2008 standard must comply with the design require- ments for the three calculated earthquake insensitivity...
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Investigating the effects of structural pounding on the seismic performance of adjacent RC and steel MRFs
PublikacjaAn insufficient separation distance between adjacent buildings is the main reason for structural pounding during severe earthquakes. The lateral load resistance system, fundamental natural period, mass, and stiffness are important factors having the influence on collisions between two adjacent structures. In this study, 3-, 5- and 9-story adjacent reinforced concrete and steel Moment Resisting Frames (MRFs) were considered to investigate...
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Innowacyjny moduł ultradźwiękowy systemu monitoringu technicznego mostu podwieszonego w Rzeszowie
PublikacjaW artykule przedstawiono system monitoringu technicznego konstrukcji mostu podwieszonego nad rzeką Wisłok. System będzie wyposażony w dodatkowy moduł ultradźwiękowy umożliwiający śledzenie degradacji mechanicznej betonu w pylonie mostu. Wczesne wykrywanie stref mikropęknięć, przed pojawieniem się widocznych rys, umożliwia monitorowanie amplitud propagującej fali ultradźwiękowej oraz analizę sygnałów w dziedzinie częstotliwości.
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Błażej Prusak dr hab.
OsobyBłażej Prusak jest kierownikiem Katedry Finansów na Wydziale Zarządzania i Ekonomii Politechniki Gdańskiej oraz redaktorem naczelnym czasopisma Research on Enterprise in Modern Economy - theory and practice (REME)/Przedsiębiorstwo we współczesnej gospodarce - teoria i praktyka, a także członkiem komitetów redakcyjnych takich czasopism jak: Intellectual Economics; Przestrzeń. Ekonomia. Społeczeństwo; Akademia Zarządzania. Jest autorem...
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A universal NDT method for examination of low energy impact damage in CFRP with the use of TLC film
PublikacjaThe article presents an attempt to use a sheet of laminated thermochromic liquid crystal film (TLC film) for non-destructive testing of the impact damage (energy values: 1J, 2J, 3J and 4J) in carbon fibre-reinforced polymer (CFRP). This is a new, alternative NDT approach based on the thermo-optical effect. The main advantages of this method are a) the low cost of TLC film, b) the low cost of recording devices due to the usage of...
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Wpływ zbrojenia polimerowymi włóknami rozproszonymi na wybrane właściwości mieszanek mineralno-asfaltowych
PublikacjaW artykule przedstawiono wybrane wyniki badań mieszanek mineralno-asfaltowych zbrojonych polimerowymi włóknami rozproszonymi. Ocenie poddano mieszankę włókien zbrojących aramidowo-poliolifenowych pod kątem wpływu ich zastosowania na właściwości niskotemperaturowe i odporności na deformacje trwałe mieszanek mineralno-asfaltowych. Właściwości niskotemperaturowe oceniano na podstawie testu zginania próbek belkowych oraz na podstawie...
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Effect of adhesive compliance in the assessment of soft adhesives with the wedge test
PublikacjaWedge tests are usually analysed assuming that the free, unbonded members may be treated as encastré cantilever beams. However, if the adhesive layer is sufficiently flexible (e.g., due to low elastic modulus), then significant strain in the bonded region may occur and lead to modification of the behaviour outside this region. Using in conjunction a sensitive strain gauge method on asymmetric wedge tests and a mathematical analysis...
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Non-Linear Analysis of Inter-Story Pounding between Wood-Framed Buildings during Ground Motion
PublikacjaPounding between adjacent buildings during ground motion may result in structural damage or lead to total destruction of structures. The research on the phenomenon has recently been much advanced; however, the analyses have been carried out only for concrete, steel, and masonry structures, while pounding between wooden buildings has not been studied so far. The aim of this paper is to show the results of detailed non-linear seismic...
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Wideband Model Order Reduction for Macromodels in Finite Element Method
PublikacjaAbstract: This paper presents a novel algorithm for accelerating 3D Finite Element Method simulations by introducing macromodels created in local model order reduction in the selected subdomains of the computational domain. It generates the projection basis for a compact system of equations associated with a separate subdomain. Due to non-linear frequency dependency in the Right Hand Side (RHS), the standard reduction methods do...
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Method of selective fading as a educational tool to study the behaviour of prestressed concrete elements under excess loading
PublikacjaPrestressed structures are a key to realization of the boldest architectural ideas, characteristic feature of prestressed structure is better use of concrete material properties by insertion of internal forces. Learning about pre-stressed reinforced concrete structures is an integral part of Graduate Studies Program in construction engineering. Know-how of geometry change patterns in prestressed concrete elements under certain...
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Multi-Fidelity Local Surrogate Model for Computationally Efficient Microwave Component Design Optimization
PublikacjaIn order to minimize the number of evaluations of high-fidelity (“fine”) model in the optimization process, to increase the optimization speed, and to improve optimal solution accuracy, a robust and computational-efficient multi-fidelity local surrogate-model optimization method is proposed. Based on the principle of response surface approximation, the proposed method exploits the multi-fidelity coarse models and polynomial interpolation...
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Wpływ ukształtowania zbrojenia na zarysowanie i nośność żelbetowego węzła tarczowego ze wspornikiem
PublikacjaPraca ma charakter eksperymentalno-teoretyczny i dotyczy zagadnień związanych z żelbetowymi tarczami pracującymi w przestrzennym układzie konstrukcji budynków. Celem niniejszej dysertacji było określenie wpływu głównych parametrów jakimi są sposób ukształtowania zbrojenia i smukłość ścinania na zarysowanie i nośność żelbetowego przestrzennego węzła tarczowego ze wspornikiem. Na podstawie aktualnego stanu wiedzy, opracowano program...
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Numerical investigations on early indicators of fracture in concrete at meso-scale.
PublikacjaFracture 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...
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Jolanta Łopatowska dr inż.
OsobyJolanta Łopatowska, adiunkt w Katedrze Inżynierii Zarządzania i Jakości na Wydziale Zarzadzania i Ekonomii, jest absolwentką Wydziału Elektroniki PG i Instytutu Organizacji i Projektowania Systemów Produkcyjnych PG oraz doktorem w dyscyplinie nauk ekonomicznych. Jej zainteresowania naukowo-badawcze koncentrują się wokół zaawansowanych organizacyjnie i technologicznie systemów produkcyjnych, ze szczególnym uwzględnieniem procesów...
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Simple empirical formula to estimate the main geomechanical parameters of preplaced aggregate concrete and conventional concrete
PublikacjaPreplaced aggregate concrete (PAC) or two-stage concrete is a specific type of concrete successfully employed in many projects including underwater concrete structures, massive concrete structures, structures made of reinforced concrete, and improvement of concrete structures. PAC is significantly different than the conventional concrete. In this type of concrete, aggregates are initially poured into the mold, the voids between...
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Introduction to European Economic Integration - Nowy
Kursy OnlineThe course is designed for students not familiar with concepts of European Integration, also for non-EU students. By the completion of the course, students will be able to define practical implications of the theory of economic integration.