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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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Fracture Surface Behavior of 34CrNiMo6 High-Strength Steel Bars with Blind Holes under Bending-Torsion Fatigue
PublikacjaThe present study evaluates the fracture surface response of fatigued 34CrNiMo6 steel bars with transverse blind holes subjected to bending with torsion loading. The analysis of the geometric product specification was performed by means of height parameters Sx, functional volume parameters Vx, and fractal dimension Df. Surface topography measurements were carried out using an optical profilometer with focus variation technology....
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Influence of low-temperature physical hardening on stiffness and tensile strength of asphalt concrete and stone mastic asphalt
PublikacjaThis paper presents laboratory testing of stiffness modulus and indirect tensile strength of three asphalt concrete (AC) and three stone mastic asphalt (SMA) mixes after isothermal storage at temperature of -20oC, at different time intervals up to 16 days. The tests under repeated dynamic loading showed physical hardening of all tested mixes which was manifested by an evident increase of their stiffness moduli after isothermal...
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MnCo2O4 deposited by spray pyrolysis as a protective layer for stainless steel interconects
PublikacjaStainless steel interconnects working in Solid Oxide Fuel Cells stacks are exposed to high temperature resulting in their corrosion. Protective layers for the hydrogen and oxygen sides are necessary to protect the interconnect material, prolongate the stack lifetime and maintain the output power. In this paper MnCo2O4 protective layer for the oxygen side of the interconnect is deposited by spray pyrolysis and is examined.
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Data-Driven Modeling of Mechanical Properties of Fiber-Reinforced Concrete: A Critical Review
PublikacjaFiber-reinforced concrete (FRC) is extensively used in diverse structural engineering applications, and its mechanical properties are crucial for designing and evaluating its performance. The compressive, flexural, splitting tensile, and shear strengths of FRCs are among the most important attributes, which have been discussed more extensively than other properties. The accurate prediction of these properties, which are required...
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Hydrogen induced degradation of structural steel exposed to the technical liquid hydrocarbons
PublikacjaSusceptibility of the differently heat treated 26H2MF steel to stress corrosion cracking has been evaluated in the constant strain rate tension tests done at the strain rate 10-6s-1 and in the constant load tests done at the 0,98 of fracture load. The boiler fuel and the aged mineral oil at 135C and 80C respectively, have been used as the aggressive environments.
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Characterization of fracture process in polyolefin fibre-reinforced concrete using ultrasonic waves and digital image correlation
PublikacjaThis study explores the monitoring of the fracture process in concrete beams and aims to characterize the evolution of damage in polyolefin fibre-reinforced concrete beams by utilizing the integrated application of two measurement techniques, digital image correlation and ultrasonic testing. The interpretation of registered wave time histories data was provided by the calculation of the magnitude-phase-composite metrics. An efficient...
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Mechanical properties of concrete mixes M0-M100 concrete mixes
Dane BadawczeDataset of hardneded properties of concretes containing different amount of magnetite aggregate (M0-M100) mixes.Excel file consists results of:
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Fresh properties of concrete mixes M0-M100 concrete mixes
Dane BadawczeDataset of fresh properties of concretes containing different amount of magnetite aggregate (M0-M100) mixes.*. ODS - open-source spreadsheet file file consists results of:
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CEMENT AND CONCRETE RESEARCH
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Bead-on-Plate Underwater Wet Welding on S700MC Steel
PublikacjaThe participation of high strength steels in marine and offshore structures is increasing, which makes it necessary to develop recommendations for underwater repair welding works. The article presents the results of bead-on-plate welded specimens made of S700MC high strength steel in underwater wet welding conditions by covered elec- trodes. Three specimens with heat input values in the range 0.91-1.05 kJ/mm were made. The specimens...
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Numerical investigations of discrete crack propagation in Montevideo splitting test using cohesive elements and real concrete micro-structure
PublikacjaThe paper is aimed at accurately predicting the discrete fracture process in concrete specimens under complex stress states in two dimensional (2D) simulations. Plain concrete specimens subjected to Montevideo splitting test (MVD) were used for consideration due to non-negligible shear stresses impact in this type of test. In order to reflect the heterogeneous nature of the concrete, the meso-structure of the samples was included...
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EXPERIMENTAL AND NUMERICAL STUDY ON COLLISIONS BETWEEN STEEL STRUCTURES UNDER EARTHQUAKE EXCITATION
PublikacjaIn the time of high urbanization, the need to build closely-spaced structures forces the designers to take into account earthquake-induced collisions between adjacent buildings and their effects on the response of structures. Past and recent investigations confirmed that interactions between adjacent buildings during earthquakes may cause serious damages to the structural elements and may even lead to total collapse of the structure....
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THE COST ANALYSIS OF CORROSION PROTECTION SOLUTIONS FOR STEEL COMPONENTS IN TERMS OF THE OBJECT LIFE CYCLE COST
PublikacjaSteel materials, due to their numerous advantages - high availability, easiness of processing and possibility of almost any shaping are commonly applied in construction for carrying out basic carrier systems and auxiliary structures. However, the major disadvantage of this material is its high corrosion susceptibility, which depends strictly on the local conditions of the facility and the applied type of corrosion protection system....
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Underwater in situ local heat treatment by additional stitches for improving the weldability of steel
PublikacjaIn this paper the influence of in situ local heat treatment performed by additional stitches on the weldability of high-strength low-alloy (HSLA) S355J2C+N steel was tested. The investigated steel is characterized by high susceptibility to cold cracking. It is necessary to find a method to improve the quality of welded joints. The local heat treatment was applied as an eect of bead-on plate welding made on the face of a Tekken...
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An experimental study of self-sensing concrete enhanced with multi-wall carbon nanotubes in wedge splitting test and DIC
PublikacjaConcrete is the worldwide most utilized construction material because of its very good performance, forming ability, long-term durability, and low costs. Concrete is a brittle material prone to cracking. Extensive cracking may impact durability and performance over time considerably. The addition of a small amount of carbon nanotubes (CNT) increases the concrete’s overall electrical conductivity, enabling internal structure...
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Two-dimensional simulations of concrete fracture at aggregate level with cohesive elements based on X-ray lCT images
PublikacjaThe paper presents results of two-dimensional meso-scale simulations of fracture in notched concrete beams subjected to three-point bending test. Concrete was assumed as a 4-phase material composed of aggregate grains placed in the cement matrix, interfacial transitional zones (ITZs) and macro-voids. The particle distribution was taken from real concrete beams on the basis of X-ray lCT images. Comprehensive numerical analyses were carried...
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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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The response of three colliding models of steel towers to seismic excitation
PublikacjaA number of past and recent observations have confirmed that collisions between adjacent, insufficiently-separated structures occurring as a result of seismic excitation (structural pounding) may result in serious damage to structural elements and can even lead to their total destruction. This paper summarises the results obtained from a shaking table experimental study which investigated structural pounding between three adjacent...
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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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Random field modelling of mechanical behaviour of corroded thin steel plate specimens
PublikacjaThe objective of this work is to explore the possibility of corrosion degradation modelling of thin steel plate specimens with the use of random field approach. The mechanical properties are obtained via the nonlinear Finite Element Analysis with the use of an explicit dynamic solver. The fully nonlinear material model is adopted to obtain the proper stress-strain response. Sensitivity analysis considering the main statistical...
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Dynamic analysis of temporary steel grandstand equipped with different types of bracing system
PublikacjaIn the paper, behaviour of a temporary steel grandstand equipped with two different types of bracing system has been analysed through the numerical study. A typical solution concerning application of a diagonal tubular members has been compared with elements proposed by authors and called polymer dampers. A polymer element consists of two L-shape steel members bonded with polymer mass. The aim of the paper is to verify the effectiveness...
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Fatigue behaviour of SLM maraging steel under variable-amplitude loading
PublikacjaOne of the most challenging issues for additive manufactured materials is fatigue endurance. Engineering components often operate under complex, variable amplitude loadings, in which existing technological imperfections promote fatigue cracks growth and damage of elements eventually. In this study the effects of different variable-amplitude strain levels on fatigue life, 18Ni300 steel was tested. The work presents various behaviours...
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Axial capacity of steel built-up battened columns
PublikacjaThis paper deals with the numerical investigation aimed to study the axial capacity of pin-ended steel built-up columns. Three methods of calculating forces in chords and batten, taking into account the material and geometric imperfections specified in the Eurocode 3 are considered. The aim of this study was to compare different methods allowing the calculation of the column load capacity and determine a simpler and faster method...
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FE investigations of the effect of fluctuating local tensile strength on coupled energetic-statistical size effect in concrete beams
PublikacjaThe effect of fluctuating local tensile strength on a coupled energetic-statistical size effect in plain concrete beams under bending was numerically investigated. First, the influence of varying autocorrelation length of the random field describing a spatial variation of local tensile strength was studied. Next, the influence of the coefficient of variation of local tensile strength was analyzed. The numerical FE investigations...
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The buckling analysis of a cold-formed steel C-sectional column resting on an elastic foundation
PublikacjaThe paper is focused on stability analysis of different models of steel cold-formed C-section column. The analysed element may be applied as a primary load-bearing member in steel trusses or silo columns. The column can be used as a support for a wall of roof plates made of corrugated sheets. The wall sheeting that restrains the column against buckling may be considered as an elastic foundation. Due to the design solutions the...
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Influence of Spatial Structures of 316L Stainless Steel on Its Cavitation Erosion Resistance
PublikacjaCavitation erosion performance of modified macroscopic internal structure 316L stainless steel was investigated. The samples processed by means of SLM method were subjected to cavitation erosion test. The scanning electron microscope Philips 30/ESEM was used to examine morphology of eroded surface.
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EH36 steel for shipbuilding - tensile test record
Dane BadawczeThe basic method of ductility designation of structural steels is the Charpy impact test. The test consists of a single strike of the specimen using a Charpy pendulum. Its result is the value of work necessary to break a specimen at a test temperature. Despite its many advantages, such as its short implementation time and low costs, it has its disadvantages,...
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On the rehabilitation of steel constructions
PublikacjaW pracy dokonano krótkiego przeglądu literatury z zakresu rewitalizacji i rehabilitacji konstrukcji stalowych. Omówiono podstawowe aspekty rewitalizacji i odnowy tego typu obiektów.
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Improvement of S355G10+N steel weldability in water environment by Temper Bead Welding
PublikacjaThe normalized S355G10 + N steel was chosen for testing, it is used in a variety of applications including the building of offshore structures, which may require repairs in water environment. The main aim of the work was to check susceptibility to cold cracking for fillet welds – Controlled Thermal Severity (CTS) tests and butt welds – Tekken tests and in the next step evaluation of effectiveness of Temper Bead Welding (TBW) application...
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Experimental study on steel columns subjected to impact load under earthquake conditions
PublikacjaEarthquakes affecting urbanized regions cause exceptional loads to load bearing structural elements such as columns. Such a boost in the load conditions can lead to severe damages which, in a worst case scenario, can lead to a total collapse of a building. This boost is caused by the horizontal ground movement generating a rise in the internal forces due to considerable large displacement between the top and bottom support of columns....
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Selection of Electrode Material for Inconel 617/P92 Steel SMAW Dissimilar Welds
PublikacjaThe present work aimed to investigate the microstructure and mechanical properties of the dissimilar shielded metal arc welded (SMAW) joint of Alloy 617 and P92 steel for advanced ultrasupercritical boilers. The SMAW joint was produced using three different types of electrodes, namely, ENiCrFe-3, ENiCrMo-3, and ENiCrCoMo-1. During microstructural observation of the welded joints, no possible cracking was detected in the weldments....
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Experimental research of the stability of steel cylindricalshell subjected to circumferential compression
PublikacjaAt the Department of Metal Structures Gdańsk University of Technology, experiments have been performed on the stability of shell of steel cylindrical models. The experiments have been carried on a test bench built at the Department. The design based on other test benches which were created in the past by other scientists, where modernized by the courtesy of companies that offer modern solutions. The test bench enables to generate...
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A dissimilar welded joint of grade 92 steel and AISI 304L steel obtained using IN82 buttering and IN617 fller: relationship of microstructure and mechanical properties
PublikacjaUnfavourable operating conditions of equipment in the energy industry resulting from high-temperature loads determine the need to use special materials and technological solutions, including welding procedures. In this article, buttering using IN82 (ERNiCr-3) consumables was proposed as a method to improve the weldability of grade 92 steel joined by the gas tungsten arc welding (GTAW) process with AISI 304L (IN617 fller). The...
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A three-dimensional meso-scale approach to concrete fracture based on combined DEM with x-ray micro-CT images
PublikacjaArtykuł omawia wyniki numeryczne uzyskane stosując 3-wymiarowy mezoskopowy model do opisu pękania w betonie na poziomie kruszywa w belce z nacięciem podczas zginania. Do obliczeń użyto metodę elementów dyskretnych. Beton został opisany jako materiał 4-fazowy złożony z kruszywa, zaprawy, makro-porów i stref przejściowych miedzy kruszywem a zaprawą. Kształt i położenia kruszywa przyjęto na podstawie skanów z mikro-tomografu. Uzyskano...
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Dynamic analysis of temporary steel grandstand subjected to human-induced excitations due to jumping
PublikacjaSteel grandstands are structures that are frequently used during sport games and many other non-sporting events, such as festivals, music concerts, or even politicians rallies, with participation of a large number of attendees. Unfortunately, the presence of unexpected excessive dynamic loads due to unpredictable behaviour of spectators (e.g. synchronized harmonic jumping or swaying) may lead to...
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Characterization of Corrosion-Induced Fracture in Reinforced Concrete Beams Using Electrical Potential, Ultrasound and Low-Frequency Vibration
PublikacjaThe paper deals with the non-destructive experimental testing of the reinforced concrete beams under progressive corrosion. A series of experiments using electrical potential, ultrasound and low-frequency vibrations techniques are reported. Electrical potential and natural frequencies were used to characterise and monitor the corrosion process at its initial state. The P-wave velocity measurements were proved to be effective in...
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The effect of long-term service at elevated temperatures on structure and mechanical properties of Cr-Mo-V steel
PublikacjaPurpose: of this paper is to reveal the microstructural changes in 13HMF steel exposed to long-term service at elevated temperatures. The degradation of bainite structure was determined and carbides morphology has been examined. The influence of carbides evolution was discussed in dependence of creep rupture strength and mechanical properties of the steel.
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Seismic damage diagnosis in adjacent steel and RC MRFs considering pounding effects through improved wavelet-based damage-sensitive feature
PublikacjaThis paper aims to propose complex Morlet (cmorfb-fc) wavelet-based refined damage-sensitive feature (rDSF) as a new and more precise damage indicator to diagnose seismic damages in adjacent steel and Reinforced Concrete (RC) Moment Resisting Frames (MRFs) assuming pounding conditions using acceleration responses. The considered structures include 6- and 9-story steel and 4- and 8-story RC benchmark...
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Imaging of Increasing Damage in Steel Plates Using Lamb Waves and Ultrasound Computed Tomography
PublikacjaThis paper concerns inspection of steel plates, with particular emphasis on the assessment of in-creasing damage. Non-destructive tests were performed on four plates, one of which was un-damaged, while the remaining three had a defects in the form of circular holes with a diameter of 2, 5, and 10 cm. Guided Lamb waves were used in the research, and the image reconstruction was performed using ultrasound computed tomography. The...
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Modal analysis of a fish-belly flap type of steel water gate
PublikacjaABSTRACT: The results of a modal analysis of the fish-belly flap type of steel water gate are presented in the paper. The analysis was conducted for a detailed numerical model of the structure using four-node quadrilateral shell elements. The study was focused on the examination of the influence of positioning of the flap gate and hydrostatic pressure of water on the eigenvalues and eigenmodes of the structure. The results of the study...
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Response of cylindrical steel tank under stochastically generated non-uniform earthquake excitation
PublikacjaCylindrical steel tanks are very important structures in industrial facilities since their application is related to storing different types of products. Their safety and reliability have become a crucial issue because any damage may cause significant consequences, including ecological disaster. The most dangerous dynamic load acting on cylindrical steel tanks is related to earthquakes, especially that the seismic excitation may...
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Concrete versus green corridors in road planning. Gdansk case
PublikacjaThe aim of an article is to present the threats which may be caused by the construction of the transit road inside the city structure, and some mitigation measures aiming to eliminate or minimize environmental and landscape damages and social problems. Theoretical guidelines and conclusions will be followed by the example illustrating the problem. As an answer, some guidelines enabling sustainable road planning will be presented....
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Kang T'ieh/Iron and Steel (Peking)
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JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
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Effects of preheating on laser beam–welded NSSC 2120 lean duplex steel
PublikacjaDuplex stainless steels show sustainable alternative for the conventional austenitic grades, with higher strength, higher resistance against stress corrosion cracking, and lower purchase cost. Thus, duplex stainless steel gains more attention in construction, oil and gas, and chemical industries. Among duplex stainless steels, low nickel and low molybdenum alloyed lean duplex stainless steel are a cost-efective substitution of...
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Problems of collisions between adjacent steel structures under earthquake excitation
PublikacjaNowadays, the high level of urbanization forces the designers to design closely-separated structures and to take into account many factors influencing the response of these structures, which may collide due to insufficient separation distance during moderate to strong ground motions. Recent observations as well as numerical and experimental investigations have confirmed that the interactions between structures may lead to significant...
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Comparative analysis of different numerical models of a steel radial gate
PublikacjaHydrotechnical structures are important components in water management system and general flooding safety. Their reliability should be ensured since potential damage might lead to catastrophic consequences. Weir gates are considered to be highly vulnerable elements of each hydro power plant, with regard to its dynamic resistance. The aim of the paper is to compare different numerical models and their influence on the results of...
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THE INTERACTION BETWEEN STEEL COLUMN CHORD AND CLOSELY SPACED REINFORCEMENT.
PublikacjaNowadays, more often than before, civil engineering designers are willing to use steel build-up members composed of single or doubled cold-formed chords interconnected using different mechanical connectors. This paper subject is an analysis of cooperation of a closely spaced built-up cold-formed chord interconnected with series of bolts that are located along the length of the member in a specific spacing. This distance along the...
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Impact of Tensile and Compressive Stress on Classical and Acoustic Barkhausen Effects in Grain-Oriented Electrical Steel
PublikacjaIn this paper, we present the results of the investigation of impact of tensile and compressive stress on the classical Barkhausen effect, magnetoacoustic emission (MAE) signal properties, and B(H) hysteresis loops for grain-oriented (GO) electrical steel. Samples have been glued to a nonmagnetic steel bar and stressed within elastic range (±800 μdef) by means of four-point bending method. The samples were cut out in two directions...