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PL
Fibrobeton, czyli beton zbrojony włóknami, otrzymywany jest przez dodanie do mieszanki betonowej włókien metalicznych lub niemetalicznych. Przeprowadzone badania miały na celu sprawdzenie, czy norma PN-EN 14651, przeznaczona do trzypunktowego testu zginania betonowych próbek zbrojonych włóknami metalicznymi, może być również zastosowana do badań betonu z włóknami syntetycznymi. Zbadano ponadto urabialność i wytrzymałość na ściskanie betonu z włóknami i bez nich. Sprawdzono również, czy dana objętość i rodzaj zastosowanej fibry mógłby zastąpić tradycyjne zbrojenie prętami stalowymi, a więc czy badany kompozyt może pełnić funkcję konstrukcyjną. W ramach badań została przygotowana betonowa mieszanka bez włókien oraz mieszanka z dodatkiem 0,22% (2 kg/m3) włókien syntetycznych. Dla obu mieszanek ilość cementu, kruszywa, wody i superplastifikatora była identyczna. W artykule omówiono podstawy prowadzenia badań, zastosowane materiały, sposób przygotowania próbek oraz technikę badań i wyniki badań wytrzymałości na ściskanie.
EN
Fiber-reinforced concrete is obtained by adding metallic or nonmetallic fibers to the concrete mixture. The tests were carried out to check whether the PN-EN 14651 standard, intended for three-point bending test the concrete samples reinforced with metallic fibers, can also be used for testing the concrete samples reinforced with synthetic fibers. In addition, the workability and compressive strength of concrete with and without fibers were tested. It was also checked whether used volume and type of fiber could replace traditional reinforcement with steel bars, and thus whether the tested composite can function as a structure. As part of the research, concrete mixture without fibers and with the addition of 0,22% (2 kg/m3) of synthetic fibers were prepared. For both mixtures, the amount of cement, aggregate, water and superplasticizer was identical. The article presents the basics of testing, materials used, method of sample preparation as well as the test technique, and the results of the compressive strength tests.
EN
Recently, numerous plant fibers have been investigated as a means to reinforce concrete and replace synthetic fibers, thereby producing more eco-friendly concretes. The primary concern for these studies is the durability of the fibers in the external environment. For this purpose, the current paper presents a comparison study on the physical-mechanical behavior and durability against external sulfatic attack on Alfa and Hemp fiber-reinforced concrete. To assess the effects of sulfatic attack, different types of concrete underwent two aging protocols: 1) a complete immersion in 12.5 % Sodium Sulfate (Na2SO4) solution and, 2) an accelerated aging protocol which consisted of immersion/drying in the same sulfate solution at a temperature of 60°C. The results show that the optimal amount of plant fiber is variable, depending on several parameters such as the chemical composition, mechanical characteristics, and morphology of the fiber. In addition, the results show that the use of Alfa and hemp fibers could facilitate the production of green and durable structural concretes.
EN
The paper deals with the working peculiarities of the support zones of reinforced concrete elements subject to bending with due account of the eccentric compression and tension. The authors performed simulation of the stress-strain behaviour of the indicated structures with the aid of “Lira” software which results are shown in the graphical and tabulated form. The performed simulation allowed of tracing the work of the studied sample beams till collapse. Such approach made it possible to single out and generalize the main collapse patterns of the inclined cross-sections of the reinforced concrete elements subject to bending on which basis the authors developed the improved method to calculate their strength (Karpiuk et al., 2019).
EN
The paper is focused on diagnostics of reinforced concrete structure of the tribune of Závodisko Bratislava. The structure was realized by a combination of monolithic and prefabricated concrete elements as well as steel load-bearing elements. The complex state of the rough construction was evaluated, including the verification survey of the foundation of the construction. Non-destructive and destructive methods were used. Based on the results of the diagnostics and recalculation, it was decided to further progress the finish of the tribune.
PL
Artykuł koncentruje się na diagnostyce konstrukcji żelbetowej trybuny zlokalizowanej na „Závodisko Bratysława”. Konstrukcja została zrealizowana przez połączenie monolitycznych i prefabrykowanych elementów betonowych oraz stalowych elementów nośnych. Oceniono złożony stan konstrukcji, w tym badanie weryfikacyjne fundamentu konstrukcji. Zastosowano metody nieniszczące i niszczące. Na podstawie wyników diagnostyki i ponownych obliczeń zdecydowano odalszych działaniach, aby ukończyć trybunę.
PL
W artykule przedstawiono analizę przyczyn uszkodzeń płyt i ścian żelbetowych dwóch najniższych, nieużytkowanych kondygnacji, wielorodzinnego budynku mieszkalnego, nadbudowanego niezgodnie z projektem o kilka pięter. Istniało podejrzenie, że znaczne zwiększenie obciążeń nadbudową jest przyczyną powstania rys na ścianach i stropach najniższych kondygnacji. Ponadto obawiano się, że penetrująca od 25-ciu lat przez rysy woda opadowa może być przyczyną korozji betonu i stali zbrojeniowej zmniejszającej nośność elementów konstrukcji. W ramach oceny stanu konstrukcji przeprowadzono badania wytrzymałościowe betonu, pomiary układu zbrojenia oraz badania właściwości ochronnych otulenia betonowego wobec stali zbrojeniowej. Wyniki badań uwzględnione w obliczeniach numerycznych modelu konstrukcji budynku pozwoliły jednoznacznie wskazać skurcz betonu jako przyczynę pęknięć płyt i ścian żelbetowych. Wykonanie nadbudowy nie było więc przyczyną uszkodzeń konstrukcji, a beton pomimo długotrwałego oddziaływania wód opadowych nie stracił swoich właściwości mechanicznych ani ochronnych wobec zbrojenia.
EN
This article presents an analysis of damage to reinforced concrete slabs and walls in two unoccupied lowest stories of the multi-family building with a few-storey upward extension incompatible with the design. A significant increase in loading caused by that extension was supposed to cause cracks in walls and floors at the lowest stories. Moreover, rainwater penetrating cracks for 25 years was expected to induce corrosion of concrete and reinforcing steel reducing the load capacity of structural members. Strength tests, measurements of the reinforcement and tests on protective properties of concrete cover to reinforcing steel were performed as part of evaluating conditions of the structure. Test results included in numerical calculations of the structure model, provided the clear finding that concrete shrinkage was the reason for cracks in reinforced concrete slabs and walls. Thus, the upward extension did not cause damage to the structure, and concrete maintained its mechanical and protective properties to reinforcement despite the long-term effect of rainwater.
PL
Od lipca 2018 r. do listopada 2019 r. firma OPTEM wraz z Zakładem Dróg i Mostów Politechniki Rzeszowskiej realizowały projekt badawczy pt.: „Innowacyjne prefabrykaty łukowe o podwyższonej trwałości przeznaczone dla budownictwa komunikacyjnego”, którego celem było opracowanie nowego prefabrykatu łukowego optemARCH. W rezultacie otrzymano znacząco ulepszony wyrób budowlany charakteryzujący się mniejszym ciężarem oraz podwyższoną odpornością na korozję.
EN
From July 2018 to November 2019, OPTEM company together with the the Department of Roads and Bridges at Rzeszow University of Technology implemented a research project „Innovative prefabricated arched components of increased durability for transportation engineering”, the aim of which was to develop a new optemARCH prefabricated arch. As a result, a significantly improved construction product of lower weight and totally corrosion resistant was obtained.
EN
The article presents the problems of building and maintaining urban transport infrastructure in Warsaw at the turn of the 20th century. The text concerns Kajetan Mościcki (1855-1933), engineer, who was appointed by the acting Mayor of Warsaw, General Sokrates Starynkiewicz, to the position of senior city engineer and head of the municipal construction department, where he worked from 1889 to 1909. During this period, he paved the streets which were worn or damaged by sewerage works with wooden blocks and covered the sidewalks with concrete slabs. He designed the first slip road in the Kingdom of Poland in the form of a spiral, and he also participated in the construction of the oldest road engineering structures made of reinforced concrete, located in Ujazdowski Park and on Karowa street in Warsaw, the first Warsaw power plant and the second city bridge across the Vistula. In addition to his professional activity, Kajetan Mościcki was an inventor in the fields of mechanics and electrical engineering. At the end of his life, he founded an award that the Polish Academy of Arts and Sciences was to grant to Polish scientists for outstanding achievements.
EN
The use of cement contributes to global CO2 emission and this leads to the depletion of ozone layer, causing global warming. The quest to reduce or eliminate this problem has resulted in the discovery of metakaolin-based geopolymer as an alternative to the use of cement in construction work. In this study, metakaolin obtained as a result of kaolin calcination from some deposits in Nigeria; Ogun (Imeko), Edo (Okpela), Ondo (Ifon) and Ekiti (Isan-Ekiti) were characterized and used to determine the compressive and flexural strength of metakaolin-based geopolymer concrete (Mk-GPC). Cubes of 150 × 150 × 150 mm were used for the compressive strength test and reinforced concrete beams of size 150 × 250 × 2160 mm were produced to test for flexural strength. A water-absorption test was also carried out on Mk-GPC and the effect of ball-milling was assessed on the strength properties. The results from the various tests showed that 800°C for 1 hour of calcination of kaolin gives best combination of performance properties due to the presence of amorphous silica in metakaolin. Mk-GPC gave higher compressive strength and at an early age than ordinary Portland cement (OPC) concrete. The water absorption capacities of Mk-GPC were higher than the control samples. In the flexural strength test, the reinforced beams failed in flexural-shear mode and the shear capacities at 28-, 56- and 90-day curing age of the beams were between 0.656 and 0.938 MPa for Mk-GPC beams and between 0.563 and 0.844 MPa for the control beams. The moment capacities for the beams were between 19.25 and 33.25 (×10³ kgm²/s²) for Mk-GPC beams and were between 22.75 and 28.0 (×10³ kgm²/s²) for the control beams. The study has revealed that metakaolin-based geopolymer can serve as an alternative to cement for sustainable construction in the Nigerian construction industry.
EN
Alfa fiber reinforced concretes are not used to their full potential due to the limited information on their properties, especially in more severe environments. In this study, the effects of elevated temperature on the properties of concretes reinforced with Alfa fiber were analyzed. The influence of fiber length on reinforced concretes is mainly investigated. For this purpose, five types of structural concretes were formulated; two types of concrete reinforced with 1% Alfa fiber volume using two different fiber lengths of 20 mm and 30 mm (AC-20, and AC-30), and three control concretes, two polypropylene fiber reinforced concretes (PC) using the same fiber length (PC-20, PC-30), and one ordinary concrete (OC). The results showed that with the increase of temperature, the mechanical performance decreased and the porosity rose continually for all mixtures. However, the use of Alfa fiber with a length of 20 mm showed the optimal results in terms of compressive and tensile strength, even at temperatures of 600°C. This finding suggests that Alfa vegetable fiber can be used to produce more sustainable concretes with acceptable mechanical properties compared to the use of polypropylene fiber, even under severe conditions of elevated temperature
EN
The purpose of this paper is to study the durability of concrete reinforced with hemp fibers in the face of external Sulfatic attack. For this purpose, five types of concrete were formulated; three types of concrete reinforced with hemp fibers (HC-0.25, HC-0.5, and HC-1) at 0.25%, 0.5%, and 1 % of hemp fibers in volume, respectively. And two control concretes, being ordinary concrete (OC) and polypropylene fiber reinforced concrete (PC). To assess the sulfatic attacks, the described concrete types underwent two aging protocols: 1) a complete immersion in 12.5 % Sodium Sulfate (Na2SO4) solution, and 2) an accelerated aging protocol consisting of immersion/drying in the same sulfate solution at a temperature of 60°C. The results show that concrete reinforced with 0.25 % of hemp fibers is the optimal amount compared to control concretes in terms of physico-mechanical performance and durability under sulfate attack. This number of fibers could enable the production of green and durable structural concretes based on untreated hemp fibers.
PL
W pracy przedstawiono badania zawartości chloru w betonie i proces korozji, w oparciu o pomiary oporu przewodnictwa elektrycznego i potencjału półogniwa próbek betonowych. Te analizy opierały się na doświadczalnych pomiarach próbek w funkcji czasu zanurzenia w 3,5% roztworze NaCl w wodzie, w temperaturze pokojowej, przez 18 miesięcy, zgodnie z europejskimi normami. Przygotowano mieszanki betonowe o różnym składzie, do których dodawano inhibitor, jakim był azotan wapnia i dwa rodzaje superplastyfikatorów. Wyniki doświadczeń pokazały, że po sześciu miesiącach zanurzenia próbki miały dużą zawartość jonów chlorkowych. Próbki C4 z dodatkiem 3% inhibitora i superplastyfikatora w formie Oxydtronu, jak również C3 z tym samym dodatkiem inhibitora i superplastyfikatora MAPEI Dynamon SR 31, wykazały dobrą odporność na korozję, w stosowanym roztworze NaCl. Znalazło to również potwierdzenie w serii pomiarów przewodnictwa elektrycznego i potencjału półogniwa, przeprowadzonych po doświadczalnym okresie 18 miesięcy.
EN
This work presents a study of the total chloride contents in concrete and the corrosion process by testing electrical resistivity and half-cell potential of concrete samples. The analysis was based on an experimental investigation of the samples with the time of immersion in 3.5% mass NaCl aqueous solution at room temperature for 18 months, according to European Standards. For this study, different mixtures of concrete were prepared by adding two types of superplasticizers and calcium nitrate inhibitor, in different concentrations. The results of the Cl- ions test showed that all the samples, after an immersion testing period of six months, contained high concentrations of Cl- ions. Samples C4 with 3% calcium nitrate inhibitor and Oxydtron superplasticizer as well as C3 with 3% calcium nitrate inhibitor and Mapei Dynamon SR 31 superplasticizer, showed good resistance to corrosion, in the tested environment. It was also proved by the results of several sets of measurements of the electrical resistivity and half-cell potentials carried on the concrete test samples, to the end of the 18 months testing period.
EN
The subject of the article is a comparison of two types of concrete carbonation models: self-limited carbonation and infinite carbonation. The results of the research on the progress of carbonation during six years of sample exposure in natural atmospheric conditions were used to determine the detailed models for a set of concretes with different w/c and different types of cement, and two scenarios of initial curing. It has been established that the model of self-limiting carbonation (i.e. hyperbolic) is more adequate for describing laboratory tests results in natural conditions.
EN
The use of old building design codes and improper execution of recent seismic design practices have caused large amount of substandard and vulnerable reinforced concrete RC building stock majority of which are built with weak beam-column joint connections defect (i.e. joint panel having no transverse reinforcement and built in low strength concrete). In order to understand the seismic response and damage behaviour of recent special moment resisting frame SMRF structures with the defect of weak beam-column joints, shake table tests have been performed on two 1:3 reduced scaled, two story RC frame models. The representative reference code design and weak beam-column joint frame models were subjected to uni-directional dynamic excitations of increasing intensities using the natural record of 1994 Northridge Earthquake. The input scaled excitations were applied from 5% to 130% of the maximum input peak ground acceleration record, to deformed the test models from elastic to inelastic stage and then to fully plastic incipient collapse stage. The weak beam-column frame experienced column flexure cracking, longitudinal bar-slip in beam members and observed with cover concrete spalling and severe damageability of the joint panels upon subjected to multiple dynamic excitations. The deficient frame was only able to resist 40% of the maximum acceleration input as compared to the code design frame which was able to resist about 130%. The seismic performance of considered RC frames was evaluated in terms of seismic response parameters (seismic response modification, overstrength and displacement ductility factors), for critical comparison.
EN
The main objective of this study is to highlight the performance of beams composed of lightweight concrete-filled steel tubes (square and circle sections) composite with reinforced concrete deck slab. A total of nine composite beams were tested included two circular and seven square concrete-filled steel tubes. Among the nine composite beams, one beam, S20-0-2000, was prepared without a deck slab to act as a reference specimen. The chief parameters investigated were the length of the specimen, the compressive strength of the concrete slab, and the effect of the steel tube section type. All beams were tested using the three-point bending test with a concentrated central point load and simple supports. The test results showed that the first crack in the concrete deck slab was recorded at load levels ranging from 50.9% to 77.2% of the ultimate load for composite beams with square steel tubes. The ultimate load increased with increasing the compressive strength of the concrete slab. Shorter specimens were more stiffness than the other specimens but were less ductile. The slip values were equal to zero until the loads reached their final stages, while the specimen S20-55-1100 (short specimen) exhibited zero slip at all stages of the load. The ultimate load of the hollow steel tube composite beam was 13.2% lower than that of the reference beam. Moreover, the ductility and stiffness of the beam were also higher for beams with composite-filled steel tubes.
EN
In this research, nonlinear analysis of composite shear walls (CSWs) with a gap between reinforced concrete wall and steel frame is investigated under cyclic loading by the use of the finite element method (FEM) software ABAQUS. For the purpose of the verification, an experimental test is modelled and comparison of its obtained result with that of the experimental test demonstrates an inconsiderable difference between them; therefore, the reasonable accuracy of the modelling is revealed. Then, effects of different parameters on the behaviour of the CSWs are examined. Gap size between reinforced concrete wall and steel frame, reinforcement percentage, steel sections of beams and columns, and existence of reinforced concrete wall are considered as parameters. It is concluded that change of the parameters affects the ultimate strength, ductility, and energy dissipation of the system. A steel shear wall (SSW) is also modelled and compared with the CSWs. Buckling of the walls is presented as well.
PL
W pracy obliczono nośność płyt żelbetowych w warunkach działania pożaru o grubościach nie mniejszych niż 15cm. Przyjęto standardową krzywą pożarową. Obliczenia wykonano uproszczoną metodą Izoterma 500. Wyznaczono krzywe równowagi pomocne do wyznaczenia nośności ogniowej analizowanych płyt. Jako pomoc dla projektantów wyniki zebrano tabelarycznie.
EN
The load capacity of reinforced concrete slabs, with a thickness not less than 15 cm, under fire conditions was calculated in the publication. A standard fire curve was adopted. The calculations were made using the simplified method of Isotherm 500. The equilibrium curves, helpful in determining the fire resistance of the analysed boards, were determined. The results were tabulated to be used by designers.
PL
W pracy obliczono nośność pożarową płyt żelbetowych o grubościach nie mniejszych niż 15 cm. Przyjęto standardową krzywą pożarową. Obliczenia wykonano przy pomocy metody Izoterma 500. Wyznaczono krzywe równowagi pomocne do wyznaczenia nośności ogniowej analizowanych płyt. Jako pomoc dla projektantów wyniki zebrano w formie tabelarycznej.
EN
The load capacity of reinforced concrete slabs, with a thickness not less than 15 cm, under fire conditions was calculated in the publication. A standard fire curve was adopted. The calculations were made using the simplified method of Isotherm 500. The equilibrium curves, helpful in determining the fire resistance of the analysed boards, were determined. The results were tabulated to be used by designers.
18
Content available remote Examining the reinforcement of a reinforced concrete industrial chimney
EN
The article exams the walls of a reinforced concrete chimney with a rectangular cross-section in Huta Częstochowa. A Ferroscan Hilti FS10 was used for the test. An example protocol of the results obtained from the device and several graphical images of the reinforcement signal are presented. Despite significant wall damage, the measurements were carried out with success. An orthogonal reinforcement solution was found. Bars in both directions differ significantly in diameter. Considerable density changes of the reinforcement in the corner zone were recorded in both the vertical and horizontal direction. As a result of the test, considerable carelessness in the reinforcement execution was observed, which manifested in a variety of cover and deviation of the reinforcement direction from the designed one. The conclusions state that a control forging the concrete up to the reinforcement and measuring the diameter of the reinforcement is necessary for the proper testing of the reinforcement using the electromagnetic method.
PL
W artykule przedstawiono badanie zbrojenia ścian komina żelbetowego o przekroju prostokątnym, na terenie Huty Częstochowa. Do badania wykorzystane zostało urządzenie Ferroscan Hilti FS10. Przedstawiono przykładowy protokół analizy wyników uzyskanych z urządzenia i kilka obrazów graficznych sygnału zbrojenia. Mimo znaczących uszkodzeń ścian pomiary udało się przeprowadzić. Stwierdzono ortogonalny układ zbrojenia. Pręty obu kierunków różnią się wyraźnie średnicą. Zarejestrowano również znaczne zagęszczenie zbrojenia w strefie narożnej zarówno w kierunku pionowym jak i poziomym. W wyniku badania stwierdzono znaczną niestaranność wykonania zbrojenia przejawiającą się zmiennością otuliny i nieprawidłowym przebiegiem prętów. We wnioskach stwierdzono, że kontrolna odkrywka zbrojenia jest niezbędna do prawidłowego przeprowadzenia badania zbrojenia metodą elektromagnetyczną.
EN
Formwork systems are necessarily used in the implementation of the RC (reinforced concrete) structures. Formworks are required regardless of whether a construction is monolithic or prefabricated and used to form the engineering and general structures or structural elements, such as abutments, supports and decks of the bridges, tanks and retaining walls, but also industrial and accommodation facilities etc. Ensuring the OHS (occupational health and safety) during transport, assembly and disassembly of formworks is a necessary condition for the execution of RC works in a safe and economical way. The paper presents the analysis of the safety requirements for formworks. Furthermore, the general requirements for the execution of the formwork structures were discussed. The most common organizational and technological mistakes and cased of neglects related to the operation of the formwork which lead to infringement of the OHS regulations were also identified.
20
Content available remote Wybrane aspekty wykonywania, eksploatacji i konserwacji fundamentów pod maszyny
PL
W artykule omówiono najważniejsze problemy związane z wykonywaniem, eksploatacją i konserwacją fundamentów pod maszyny. Przedstawiono najnowsze rozwiązania dotyczące technologii realizacji tych konstrukcji i materiałów wykorzystywanych do ich budowy. Fundamenty pod maszyny to specjalne konstrukcje w budownictwie przemysłowym, służące do przekazywania obciążeń z działającej maszyny na podłoże gruntowe. Ich celem jest nie tylko przenoszenie obciążeń, ale także zmniejszenie drgań występujących podczas pracy maszyny, tj. ich wytłumienie i przeciwdziałanie redystrybucji na inne elementy budynku. Należy zauważyć, że fundamenty pod maszyny (szczególnie pod młoty) są najbardziej dynamicznie obciążanymi konstrukcjami budowlanymi. Z tych powodów wymagają dokładnych obliczeń statycznych oraz dynamicznych, poprawności wykonania i dbałości o nie podczas eksploatacji.
EN
This paper presents the most important issues on the implementation, operation and maintenance of foundation for machines. The newest solutions focus on terms of technology implementation and materials used in construction of such structures have been presented. Foundations for machines are special structures in industrial construction, used to transfer loads from an operating machine to the subsoil. However, the purpose of these foundations is not just to transfer loads, but also to reduce vibrations occurring during operation of the machine, i.e. their damping and preventing redistribution to other elements of the building. It should be noted that foundations for machines (particularly for hammers) are the most dynamically loaded building structures. For these reasons, they require: precise static and dynamic calculations, accuracy in their implementation and care for them after they have been made.
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