Wyniki wyszukiwania - BazTech

1

Stanowisko badawcze do wyznaczania wytrzymałości na ścinanie połączeń ścian murowanych

Galman Iwona, Jasiński Radosław

Materiały Budowlane

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2025

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nr 2

63--64

2

Właściwości użytkowe ważne w kontekście projektowania murów

Fudalej Piotr, Łaskawiec Katarzyna, Wieczorek Michał

Materiały Budowlane

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2024

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nr 4

54--57

3

Municipal waste management based on geomechanical assessments of the landfill site slope - a case study in southern Poland

Janoszek Tomasz, Nguyen Phu Minh Vuong, Grabowski Jacek

Journal of Sustainable Mining

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2024

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Vol. 23, iss. 2

185--198

EN

Over time, municipal waste landfills tend to go higher and become larger. The stability of the municipal landfill slope is one of the basic geotechnical tasks. This task ensures continuous waste deposition on the landfill surface and safety in its surroundings. With the increasing height and volume of the landfill, it is difficult to estimate the available area of the municipal landfill, where more waste can be safely deposited due to a number of variable factors, such as the geotechnical conditions of the municipal landfill, the morphological composition, age, and degree of compaction and decomposition of the deposited waste. This paper presents an attempt to determine the available area of a landfill where municipal waste can be safely deposited for further operation. For this purpose, a numerical slope stability analysis was carried out using the finite difference method code FLAC3D, presenting the actual geomechanical conditions of a landfill located in southern Poland. Based on the numerical results, options for municipal waste storage were presented and discussed. The proposed design chart aims to help landfill owners/managers make an adequate decision in terms of landfill planning and design.

4

Numerical Assessment of CFS-SWP with Different Door Opening Positions

Rouaz Idriss, Rafa Sid Ali, Ghribi Zakaria

Inżynieria Mineralna

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2024

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Vol. 1, no. 2

art. no. 21

EN

A prevalent method of countering lateral forces in seismic regions for structures made of Cold Formed Steel (CFS) involves employing Shear Walls Panels (SWP) covered with steel sheets. The overall reaction and various failure modes during lateral loading have become apparent, continuing to capture the interest of designers and researchers. Typically, door openings are everpresent in the front and rear elevations where SWPs find their optimal position to ensure lateral stability in CFS structures. These architectural design features translate into reduced areas for lateral load resistance throughout the structure. Through numerical simulations, this paper discusses the effect of the door opening, with different positions in the SWP, on the shear strength performance of CFS-SWP. A Finite Element (FE) modelling is developed using the ABAQUS software, taking into account material and geometrical nonlinearities, as well as assembled sheathing-to-framing connections. In order to validate the FE modelling with available experimental data, comprehensive static nonlinear analyses are conducted on CFS-SWP under monotonic load. A good agreement is achieved, namely: nonlinear strength-displacement response, ultimate shear strength, and failure modes. The effect of the door positions is assessed, in which, the opening position is found to have a significant impact on the CFS-SWP performance. The results reveal that the position of the door opening between the central and the edge of the SWP produces better performance than the other positions. However, the position of the door at the edge of the SWP induces additional failure modes in the vicinity of the chord studs.

5

Impact loading of tendon reinforcement systems used for ground control: a critical literature review

Mottahedi Adel, Aziz Naj, Remennikov Alex, Mirzaghorbanali Ali, Marston Kevin

Archives of Mining Sciences

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2024

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Vol. 69, no. 4

711--743

EN

The present paper reports on various test methods and techniques which have been developed throughout the last decades. These methods have been used to evaluate both axial and shear performance of tendons under impact loading mode. Based on the literature review conducted on the scientific documents, published between 1992 and 2024, the developed facilities mainly work based on the direct impact and momentum transfer methods. In the direct impact method, which can be done in-situ and in the laboratory, the impact energy is applied by a mass freely falls to the test sample. In the momentum transfer method, the test assembly, consisting of both the mass and test sample free-fall at the beginning of the test until the movement of the assembly is halted by a stopper, and the momentum of the mass is transferred to the test sample. Besides, most of the current facilities are working based on the direct impact method. It was also found that less research have been conducted on dynamic shear testing, especially high-strength cable bolts, as most of the facilities have been designed for pull testing. In addition, it was found that in dynamic pull-out tests of rock bolts, two main mechanisms of energy absorption are identified: steel plastic deformation and bolt sliding within the encapsulation medium. The first impact plays a key role in energy absorption, causing significant permanent displacements, while the energy consumed in displacing the bolt is more indicative of dynamic behavior than the total input energy. According to the results, the tendons that undergo static deformations before dynamic loading are more prone to failure as some parts of their performance have already lost. Meanwhile, differences between dynamic and static shear tests suggest that dynamic tests require less energy for failure, as friction is ineffective in impact loading. Finally, the study highlights gaps in the current understanding of tendon performance under impact loading, with potential research directions aimed at improving safety in underground excavation.

6

Random shear resistance of a headed-stud connector in composite steel-concrete beam

Domański Tomasz, Maślak Mariusz

Archives of Civil Engineering

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2024

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Vol. 70, nr 4

425--439

EN

In the traditional, standard, computational approach, the shear resistance of a single headed-stud connector, ensuring the composite connection between a steel beam and a reinforced concrete slab resting on this beam, is determined by comparing the load capacity PRs – determined by the destruction of the steel connector itself, and the load capacity PRc – conditioned by the destruction of the concrete surrounding this connector. In a single implementation, the smaller of these both values, i.e. PR = min (PRs, PRc ), is authoritative for the designer. If, however, both combined strengths are treated as the random variables and a statistically homogeneous sample grouping potentially possible implementations of this type is taken into account, then the design resistance PR,d = [min (PRs, PRc)]d, representative for the verification of ultimate limit state for the considered connection, will be quantitatively different from the value PR,d = min (PRs,d; PRc,d) recommended for use in this regard in the standard EN 1994-1-1. In this paper a detailed algorithm for the correct specification of this value is presented in detail. The dependence of such value on the mutual relationship between the coefficients determining the statistical variability of the strength of the connector steel as well as the strength of the concrete from which the floor slab was made is also demonstrated. The proposed approach is based on the fully probabilistic design format, according to which the appropriate level of the probability of reliable work of the analyzed connection is ensured. The presented considerations are illustrated with a numerical example. On its basis, the degree of simplification of such evaluation is estimated, as well as its consequences, resulting from the use of a conventional standard model in this respect.

PL

W tradycyjnym, normowym, ujęciu obliczeniowym nośność na ścinanie pojedynczego łącznika sworzniowego z główką, zapewniającego zespolenie belki stalowej z opartą na tej belce płytą żelbetową, określana jest przez porównanie ze sobą nośności PRs – determinowanej zniszczeniem samego łącznika stalowego, oraz nośności PRc – warunkowanej zniszczeniem betonu otaczającego ten łącznik. W pojedynczej realizacji miarodajną dla projektanta jest mniejsza z tych wartości, a zatem PR = min (PRs, PRc). Jeżeli obie zestawione ze sobą wytrzymałości potraktować jako zmienne losowe i rozpatrywać statystycznie jednorodną próbę grupującą realizacje potencjalnie możliwe to obliczeniowa nośność PR,d = [min (PRs, PRc)]d, reprezentatywna dla weryfikacji stanu granicznego nośności rozpatrywanego połączenia, będzie ilościowo różna od wartości PR,d = min (PRs,d, PRc,d) zalecanej do stosowania w normie EN 1994-1-1. W niniejszej pracy pokazano szczegółowy algorytm poprawnego specyfikowania tej wartości. Wykazano jej zależność od wzajemnej relacji pomiędzy współczynnikami określającymi statystyczną zmienność wytrzymałości stali łącznika i wytrzymałości betonu, z którego wykonano płytę stropową. Zaproponowane podejście opiera się na w pełni probabilistycznym formacie obliczeń, w którym gwarantuje się odpowiednie prawdopodobieństwo niezawodnej pracy analizowanego połączenia. Rozważania zilustrowano przykładem numerycznym. Na jego podstawie oszacowano stopień uproszczenia, a także jego konsekwencje, wynikające z zastosowania w tym zakresie konwencjonalnego modelu normowego.

7

Effect of shear rate and saturation on shear strength of mineral and anthropogenic soil

Gruchot Andrzej, Zydroń Tymoteusz

Archives of Civil Engineering

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2024

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Vol. 70, nr 2

97--117

EN

The aim of the study was to determine the shear strength of mineral and anthropogenic soil of similar grain size as a function of the applied shear rate and water saturation. Stability calculations using the finite element method of the road embankment model were also carried out to demonstrate the variation in factor of safety values depending on the adopted values of the angle of internal friction and cohesion. The tests were carried out in a direct shear apparatus in a 100 x 100 mm box with a sample height of 20.5 mm. The samples were formed directly in the apparatus box at optimum moisture content until a compaction index of IS = 1.00 was obtained. Tests were carried out under conditions without and with water saturation at shear rates of 0.01, 0.05, 0.1, 0.5 and 1.0 mm·min-1 until 18% horizontal displacement was achieved. The results showed that the effect of shear rate on the strength parameters was not unequivocal and was much smaller than the changes caused by saturation of samples. An increase in shear rate resulted in small changes in the angle of internal friction with a tendency towards a decrease. In contrast, cohesion varied over a much larger range with increasing shear rate, with an apparent initial decrease and subsequent increase. The saturation of the samples resulted in a decrease in the angle of internal friction of the cohesive soil and an increase for the ash-slag mixture. The cohesion of both soils decreased. The results obtained from the road embankment model stability calculations confirmed that soil saturation had a greater influence on the factor of safety values obtained than the shear rate.

PL

Celem pracy było określenie wytrzymałości na ścinanie gruntu mineralnego i antropogenicznego w zależności od zastosowanych prędkości ścięcia i zawodnienia. Wykonano również obliczenia stateczności metodą elementów skończonych modelu nasypu drogowego w celu wykazania zmian w wartościach współczynnika stateczności w zależności od przyjętych wartości kąta tarcia wewnętrznego i spójności. Badania przeprowadzono w aparacie bezpośredniego ścinania w skrzynce o wymiarach 100 × 100 mm i wysokości próbki 20,5 mm. Próbki formowano bezpośrednio w skrzynce aparatu przy wilgotności optymalnej do uzyskania wskaźnika zagęszczenia IS = 1,00. Badania przeprowadzono w warunkach bez i z zawodnieniem przy prędkości ścięcia 0,01, 0,05, 0,1, 0,5 i 1,0 mm·min-1. Wyniki badań wykazały, że wpływ prędkości ścięcia na parametry wytrzymałości nie był jednoznaczny i był znacznie mniejszy niż zmiany spowodowane zawodnieniem próbek. Wzrost prędkości spowodował niewielkie zmiany kąta tarcia wewnętrznego z tendencją na jego zmniejszenie. Natomiast spójność wraz ze wzrostem prędkości ścięcia wahała się w znacznie większym zakresie, z widocznym początkowym jej zmniejszeniem, a następnie zwiększeniem. Uzyskane wyniki obliczeń stateczności modelu nasypu drogowego potwierdziły, że większy wpływ na uzyskiwane wartości współczynnika stateczności miało zawodnienie gruntu niż prędkość ścięcia.

8

Effect of polypropylene fibres on the shear strength of fine-grained soil

Zydroń Tymoteusz, Gruchot Andrzej, Zawiła Dominika

Archives of Civil Engineering

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2024

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Vol. 70, nr 3

325--341

EN

This paper presents the results of shear strength tests of fine-grained soil reinforced by randomly oriented fibres. The tests were carried out in a direct shear apparatus on samples with a diameter of 100 mm and a height of 20 mm. The samples were formed directly in the apparatus box at a natural moisture content and two values of the degree of compaction (IS = 0:79 and 0.90). The studies were carried out for samples of natural moisture content and for soaked ones. The two types of polypropylene fibres were used: monofilament and fibrillated (of traded names Fibermesh 300-e3 and SikaCem Fiber-12, respectively). The fibre content was 0.25; 0.50 and 1.00% by the weight of the dry soil. The results showed that the presence of fibre within the soil increased its the shear strength. The improvement of the shear strength was related to the type of reinforcement, its content and the soil parameters. The maximum increase in shear strength was 47% compared to the shear strength of the unreinforced soil. The increase in shear strength values were related mainly to the increase in the angle of internal friction of the soil. It was found that as the degree of compaction of the soil increases, the higher enhance of the shear strength of reinforced soil occurs. It was also found that the improvement of shear strength of reinforced soaked samples was more significant than for un-soaked ones.

PL

W pracy przedstawiono wyniki badań wytrzymałości na gruntu drobnoziarnistego z dodatkiem zbrojenia rozproszonego. Oznaczenie parametrów wytrzymałości na ścinanie przeprowadzono w aparacie bezpośredniego ścinania na próbkach o średnicy 100 mm i wysokości 20 mm. Próbki były formowane bezpośrednio w skrzynce aparatu przy wilgotności naturalnej, zbliżonej do optymalnej, oraz dwóch wartościach wskaźnika zagęszczenia (IS = 0,79 i 0,90). Próbki konsolidowano przez 60 min przy naprężeniu normalnym 25, 50, 75, 100, 125 kPa, a następnie ścinano z prędkością 0,10 mm·min-1 do momentu uzyskania 18% względnego odkształcenia. Badania przeprowadzono dla zawodnionych niezawodnieniem próbek gruntu. Zbrojenie rozproszone stanowiły dwa rodzaje włókien polipropylenowych (monofilamentowe i fibrylowane o nazwach handlowych odpowiednio Fibermesh 300-e3 oraz SicaCem Fiber-12), które dodawano w ilości 0,25; 0,50 i 1,00% w stosunku do masy szkieletu gruntu. Wyniki badań wykazały, że zastosowanie zbrojenia rozproszonego wpływa pozytywnie na wytrzymałość na ścinanie gruntu, przy czym wpływ ten jest zależny od rodzaju zbrojenia, jego dodatku, a także parametrów geotechnicznych gruntu. Maksymalny wzrost wytrzymałości na ścinanie gruntu ze zbrojeniem wyniósł 47% w stosunku do wartości wytrzymałości na ścinanie gruntu bez dodatku zbrojenia. Stwierdzono, że dodatek zbrojenia wpłynął zasadniczo na wartości kąta tarcia wewnętrznego, a w przypadku spójności był niejednoznaczny. Wyniki badań wykazany również, że włókna monofilamentowe mają bardziej korzystny wpływ na wzmocnienie gruntu niż włókna fibrylowane. Wykazano również, że wpływ zbrojenia na wzmocnienie gruntu jest bardziej efektywny przy wyższym wskaźniku zagęszczenia gruntu, a większy przyrost wytrzymałości na ścinanie gruntu uzyskano w przypadku badań próbek zawodnionych.

9

Shear behavior of prestressed UHPC rectangular beams: experimental investigation and limit equilibrium state‑based prediction method

Sun Bin, Luo Rui, Quan Chenghao, Song Chaolin, Xiao Rucheng

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 1

art. no. e31, 2024

EN

Ultra-high performance concrete (UHPC) is a durable and versatile construction material that enables the engineering of slender fabricated beams. Nonetheless, existing design methodologies exhibit certain discrepancies in predicting the ultimate shear capacity of UHPC beams. This study aimed to develop an improved predictive shear model based on design and mechanical properties. Eleven prestressed rectangular UHPC beams were subjected to shear tests, systematically investigating essential design parameters such as shear-span-to-depth ratio, stirrups ratio, longitudinal reinforcement ratio, prestressing force, and prestressing type. The results demonstrated that UHPC beams exhibit strain-hardening behavior after cracking, accompanied by the formation of dense diagonal cracks. Localized cracking eventually led to shear failure. The shear behavior was primarily influenced by the shear-span-to-depth ratio, showing an inverse relationship with shear strength. Increasing the longitudinal reinforcement ratio, stirrups ratio, and prestressing force marginally improved shear capacity. Furthermore, a limit equilibrium state-based method was proposed to develop a practical prediction formula that incorporates steel fibers and matrix interaction. The proposed method demonstrated superior accuracy compared to existing design models, displaying an average difference of 1.1% and a correlation coefficient of 0.96 with experimental results.

10

Intricacies of various printing parameters on mechanical behaviour of additively constructed concrete

Pal Biswajit, Chourasia Ajay, Kapoor Ashish

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 1

art. no. e41, 2024

EN

Extrusion-based three-dimensional (3D) printing has seen rapid growth in the last few years, including in the construction sector owing to its reduced construction cost, minimal labour intervention, freeform design, implementation of complex architectural structural design and more. However, like other technologies, additive construction or 3D concrete printing has several limitations such as additional requirement of printing performance of the material along with hardened mechanical properties, construction challenges of the additive construction in the case of large-scale reinforced concrete structures, accuracy and performance of the digital 3D print model are the few. Moreover, the lack of understanding about the effect of various printing-related parameters on the load capacity of additively manufactured structural element is another barier in the popularisation of such technology. Consequently, in this article, a finite-element (FE)-based framework is utilised and the load–deflection of additively constructed concrete beam under 4-point loading is simulated. In the model, measured geometrical specifications of additively manufactured specimen (length and sectional curvatures, varying width and thickness at different layers along the beam depth), are utilised. Each concrete filament is modelled using coupled damage-plasticity-based material behaviour, whereas cohesive zone-based constitutive behaviour is used to represent the interfacial bond characteristics between two printed filaments. In the model, the input properties such as mechanical properties of concrete (e.g. compressive and tensile strength) and the tensile bond strength value of the interfaces are obtained from the respective experiments conducted. A detailed sensitivity analysis for the various printing-related parameters, e.g. tensile and shear bond strength, bond stiffness, plastic or failure displacement of bond, pores or gaps that exist between two consecutive printed filament and the number of printed layers, have been conducted. In the simulation, one parameter at a time is varied keeping all other fixed and the resultant effect on the load–deflection behaviour is analysed. The simulated results of the concrete specimen for various above-mentioned printing parameters are also compared with the results obtained from the perfect bond condition. Consequently, simplified statistically fitted relations are proposed that helps in quick evaluation of the variability in load-carrying capacity of additively constructed concrete beam for variable bond or printing conditions. The results of such studies would be helpful for the research community in the design and prediction of load capacity of additively manufactured concrete beam.

11

Experimental and numerical investigation on shear and bond-slip behaviors of FSK‑reinforced FRP-UHPC composite beams

Ge Wenjie, Zhang Zhiwen, Ashour Ashraf, Jiang Hongbo, Li Shengcai, Cao Dafu

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e87, 2024

EN

The shear performance of fiber-reinforced polymer (FRP)-ultra-high-performance concrete (UHPC) composite beams with FRP shear keys (FSK) was investigated through a four-point loading test and refined finite element (FE) analysis. In total, five test specimens having different concrete strength, concrete slab width and height as well as FSK spacings were experimentally tested. The test specimens were simulated using a refined FE model in ABAQUS. The concrete damaged plasticity model (CDPM) and the Puck failure criterion were adopted to simulate the progressive damage of concrete and FRP profiles, respectively. The mechanical behavior of the interface was captured using a bilinear cohesive zone model (CZM). The comparison between the FE analysis and experimental results demonstrated a good agreement. Based on the validated model, a parametric analysis was conducted on the shear performance of FRP-UHPC composite beams with FSK, focusing on parameters such as concrete slab strength, height and width, FRP web shear strength, shear modulus, height and thickness, and FSK spacing. The results indicate that the maximum local slip beam is less than 4 mm, which verifies that FSK has good interfacial shear resistance. Increasing the strength and section size of the concrete slab can improve the flexural stiffness and the shear capacity of composite beams. The use of UHPC for concrete slabs can also effectively inhibit interface slip. Increasing the shear strength and thickness of FRP web can result in improved load-carrying capacity and reduced deformation of composite beams. This can also lead to a shift in the failure mode from shear failure to bending failure. The reduction of FSK spacing can effectively enhance the shear performance of the interface, thereby improving the composite action and increasing the bearing capacity and deformation resistance of composite beams.

12

Wpływ zróżnicowanego składu kompozytu geopolimerowego na adhezję z kompozytem asfaltowym

Granatyr Krzysztof, Bołtryk Michał, Kalinowska-Wichrowska Katarzyna, Szeligowski Paweł

Materiały Budowlane

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2023

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nr 5

5--9

PL

W artykule przedstawiono badania wpływu zróżnicowanego składu kompozytu geopolimerowego na adhezję z kompozytem asfaltowym. Zmiennymi w planie eksperymentu były zawartość zaprawy geopolimerowej, stężenie molowe NaOH oraz grubość warstwy ochronnej kompozytu geopolimerowego. Przyjęto stałe warunki dojrzewania. Otrzymane wyniki wskazują na bardzo dobre właściwości kompozytu zespolonego niezależnie od badanych czynników.

EN

The article presents the research on the influence of the variable composition of the geopolymer composite on the adhesion with the asphalt composite. The variables in the experiment plan were the content of the geopolymer mortar, the molar concentration of NaOH and the thickness of the protective layer made of the geopolymer composite. Constant maturation conditions were assumed. The obtained results indicate very good properties of the composite regardless of the tested variable.

13

Shear strength characteristics of weathered jointed Kenny Hill interbedded formation for cylindrical specimen under direct shear test

Abbas Hasan Ali, Mohamed Zainab, Taher Muntadher J., Kudus Sakhiah Abdul, Salman Manaf Raid, Ghaltan Hasanain Muhammad

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 2

1--12

EN

The sliding failures commonly occur in interbedded formations along the weakness plane of the bedding plane a sedimentary rock or the joint interface. Therefore, studying the shear strength characteristics at the bedding plane or interface is crucial for evaluating the expected failure plane. In this study, the shear strength characteristics of planar jointed Kenny Hill shale, sandstone, and shale-sandstone specimens were investigated using the direct shear box method. The results reveal that the friction angle values for the planar sandstone, shale-sandstone, and shale are 31.28°, 21.1°, and 19.34°, respectively. These findings, combined with the shear stress-strain behavior, suggest that the interface (shale-sandstone) is primarily influenced by the shale characteristics rather than the sandstone characteristics. Hence, it is important to consider failure along the interface when analyzing critical conditions, particularly in slope failure scenarios.

14

Laboratory tests of solid and hollow concrete beams made with glass waste

Alharishawi Salam Salman Chiad, Rajaa Nagham, Jabur Aqeel Raheem

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

5--20

EN

The application of used glazed waste in concrete production can improve the performance of the structure of the building. Flexural and shear behavior and action of reinforced Hollow Glass Concrete Beams (HGCB) and Solid Glass Concrete Beams (SGCB) made with glass waste under a two-point load are studied in this paper. In this work, 6 reinforced concrete solid and hollow beams were tested under a four-point bending test to evaluate and calculate the flexural behavior of SGCB and HGCB. For that purpose, Beams were prepared with 1000 mm length, 230 mm height, and 120 mm. All beams were divided into groups and named according to the space stirrups steel bar. The experimental work investigates five main variables which are: first: the comparison between SGCB and HGCB with the concrete beams made with glass waste (Glass Concrete Beam GCB), second: comparison between Solid Concrete Beams for Normal Concrete Beams (NCB), and GCB, three: comparison between Hollow Concrete Beams for NCB and GCB, four: the comparison between HGCB and HCB, last: the comparison between SGCB and SCB. The test results indicated that GCB was offered higher strength than NCB, but the load-slip behavior of all specimens is similar for both types of concretes, and the bond strength is not influenced by steel specimens. Furthermore, the results of this study indicated that the contribution of GCB to the load is indicated to be considerable. The results indicate that the hollow opening affected the ultimate load capacity and deflection of HGCB.

15

Cyclic response and shear mechanisms of RC short walls strengthened with engineered cementitious composites thin layers

Zhang Yangxi, Zhang Shijun, Li Tong, Deng Mingke

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e148, 2023

EN

This paper investigates the effectiveness of engineering cementitious composites (ECC) thin layers for seismic strengthening of reinforced concrete (RC) short walls with high axial load ratios. Three RC short walls with an aspect ratio of 1.1 were tested under cyclic loading: one control wall and two ECC strengthened walls, adopting two different strengthening layer schemes. The results showed that the failure mode, damage tolerance, lateral stiffness, shear strength, and energy dissipation of the strengthened walls were improved to certain extents. The mesh grid ECC layer was proved an effective and applicable technique, the shear strength and energy dissipation of the corresponding strengthened wall were improved by 37.2% and 33.5%, respectively, and the addition of mesh grid and tie bars in the ECC layer prevented the debonding failure at the ECC/concrete interface. Besides, the shear resistance mechanisms of the test specimens were idealized by the strut-and-tie model, the contribution of cracked ECC tensile strength to shear was considered in the horizontal and vertical mechanisms. The predicted shear strengths of the RC walls agreed well with the test values.

16

The influence of the manufacturing method on the mechanical properties of the honeycomb core sandwich composite

Janiszewski Jacek, Przybyłek Paweł, Bieńczak Rafał, Komorek Łukasz, Schwarzenberg Miłosz

Technologia i Automatyzacja Montażu

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2022

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nr 4

20--33

EN

Reducing weight and fuel consumption is one of the main goals of modern aeronautical engineering. The most common materials to achieve this goal are composite layered materials, including the sandwich ones. High strength, stiffness and low density have made sandwich composites one of the fundamental materials of the aerospace industry. Sandwich-structured composites can be manufactured with a variety of methods, differing primarily in the manufacturing time, which translates into an overall cost of making a composite component. The research focused on three methods of manufacturing sandwich composite materials with a honeycomb core, differing in the number of operations, during which it was possible to obtain a finished composite panel (single-phase, two-phase and three-phase methods). The authors manufactured and examined composites with a honeycomb cover and two composite glass fibre-reinforced covers. The composites were made by means of the vacuum bag method. As a result of the conducted study, it was found that composites manufactured with the single-phase method have the shortest manufacture time as well as the lowest material consumption, however their strength properties are the lowest. The two-phase method requires a longer manufacture time and more material consumption, however it makes it possible to obtain a composite with higher strength compared with the single-phase method. The three-phase method has the longest composite manufacture time and the highest material consumption.

PL

Zmniejszenie masy i zużycia paliwa jest jednym z głównych celów współczesnej inżynierii lotniczej. Najpopularniejsze materiały, które pozwalają osiągnąć ten cel, to materiały kompozytowe warstwowe w tym przekładkowe. Wysoka wytrzymałość, sztywność i niska gęstość, sprawiły, że kompozyty przekładkowe stały się jednym z podstawowych materiałów przemysłu lotniczego. Kompozyty przekładkowe z wypełniaczem strukturalnym mogą być wytwarzane różnymi metodami, różniącymi się przede wszystkim czasem wytwarzania, co przekłada się na ogólny koszt wykonania elementu kompozytowego. W badaniach przeanalizowano trzy metody wytwarzania materiałów kompozytowych przekładkowych w wypełniaczem ulowym różniące się liczbą operacji podczas których uzyskano gotową płytę kompozytową (metoda jednofazowa, dwufazowa i trójfazowa). Wytworzono i badano kompozyty zbudowane z rdzenia ulowego oraz dwóch kompozytowych okładek wzmacnianych włóknami szklanymi. Kompozyty wykonano metodą worka próżniowego. W efekcie przeprowadzonych badań stwierdzono, że kompozyty wytworzone metodą jednofazową cechują się najkrótszym czasem produkcji jak i najmniejszym zużyciem materiałów, ale ich właściwości wytrzymałościowe są najniższe. Dwufazowa metoda wymaga dłuższego czasu produkcji i większego zużycia materiałów, natomiast pozwala uzyskać kompozyt o większej wytrzymałości w porównaniu do metody jednofazowej. Trójfazowa metoda cechuje się najdłuższym czasem wykonania kompozytu i największym zużyciem materiałów.

17

Effect of overlap length on the strength of adhesive joints of steel sheets

Doluk Elżbieta, Rudawska Anna, Miturska-Barańska Izabela, Ogrodniczek Jacek

Technologia i Automatyzacja Montażu

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2022

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nr 4

3--6

EN

The study evaluates the shear strength of the single-lap adhesive joints made of C45 carbon steel. The influence of the overlap length on the shear strength of the adhesive joint was tested. The elongation of the samples was also tested. Before the bonding process, the samples were treated with P180 abrasive paper and degreased. The adhesive joints were made using the Epidian 53/Z1/100:10 adhesive composition. The strength tests were carried out on a Zwick/Roell Z150 testing machine. The maximum value of the shear strength was obtained for the lap Lz1 = 13 mm and the minimum for Lz4 = 19 mm.

PL

W pracy dokonano oceny wpływu długości zakładki na wytrzymałość na ścinanie jednozakładkowych połączeń klejonych wykonanych ze stali węglowej C45. Podczas eksperymentu zbadano także wydłużenie próbek. Przed rozpoczęciem procesu klejenia próbki zostały obrobione papierem ściernym P180 i odtłuszczone. Połączenia klejowe wykonano przy użyciu kompozycji klejowej Epidian 53/Z1/100:10. Badania wytrzymałościowe przeprowadzono na maszynie wytrzymałościowej Zwick/Roell Z150. Maksymalną wartość wytrzymałości na ścinanie uzyskano dla długości zakładki Lz1 = 13 mm, a minimalną dla Lz4 = 19 mm.

18

Analiza pracy poprzecznej łączników prętów jako przykład działań B+R w nowoczesnej prefabrykacji betonowej

Surma Mateusz, Wojciechowski Szymon

Materiały Budowlane

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2022

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nr 3

28--29

19

Characterisation of spoil materials to develop an equivalent spoil material for physical model tests

Garala Thejesh Kumar, Cui Ge, Kantesaria Naman, Heron Charles M., Marshall Alec M., Žižka Lukáš

Górnictwo Odkrywkowe

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2022

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R. 63, nr 4

23--29

EN

The engineering behaviour of spoil (overburden) needs to be explored either to understand the stability of reservoir slopes under various geological and climatic conditions or for the effective utilisation of reclaimed mines for sustainable infrastructure (e.g., onshore wind turbines). The spoil material is usually considered as highly heterogeneous, and samples collected from the same site can exhibit widely varying characteristics. In this study, spoil material from a mine site in the Czech Republic is characterised using in-situ field tests and laboratory tests. Cone penetration tests were performed in the field and sample cores were collected for laboratory testing. In the laboratory, the index and engineering characteristics of the spoil were evaluated. Given the measured characteristics and behaviour of the field spoil, an equivalent spoil is proposed to perform physical modelling tests using geotechnical centrifuge. This enables simulation of the field spoil behaviour in controlled centrifuge testing, from which other aspects of spoil (e.g. stability of spoil slopes, spoil-structure interaction) can be investigated.

PL

Zachowanie zwałowisk pogórniczych (nadkładu) pod względem inżynieryjnym powinno zostać zbadane w celu określenia stabilności zboczy zbiorników poeksploatacyjnych w różnych warunkach geologicznych i klimatycznych lub w celu efektywnego wykorzystania rekultywowanych kopalń do budowy zrównoważonej infrastruktury (np. lądowych turbin wiatrowych). Materiał zwałowisk pogórniczych jest zwykle uważany za wysoce niejednorodny, a próbki pobrane z tego samego miejsca mogą wykazywać bardzo różne właściwości. W niniejszej pracy, materiał odpadowy z czeskiej kopalni został scharakteryzowany przy użyciu badań terenowych i laboratoryjnych in-situ. W terenie przeprowadzono sondowania CPT, a do badań laboratoryjnych pobrano próbki rdzeniowe. W laboratorium oceniono właściwości indeksowe i inżynieryjne materiału. Biorąc pod uwagę zmierzone cechy i zachowanie się materiału pogórniczego, zaproponowano materiał równoważny do wykonania modelowania fizycznego z wykorzystaniem wirówki geotechnicznej. Umożliwia to symulację zachowania się materiału w kontrolowanych badaniach wirówkowych, na podstawie których można badać inne cechy materiałów pogórniczych (np. stabilność skarp zwałowiska, interakcje zwałowisko-konstrukcja budowlana).

20

Shear capacity of the interface between concretes cast at different time in the light of experimental investigations and codes of practice

Gołdyn Michał

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

275--298

EN

The paper presents selected issues related to the load carrying capacity of joints between concretes cast at different times. The most important factors affecting the shear resistance, such as: surface roughness (profile), shear reinforcement ratio, concrete strength as well as the aggregate composition are discussed, including results of previous experimental studies conducted on push-off specimens and composite reinforced concrete beams. The differences in behaviour and shear resistance of contacts between ordinary concretes, lightweight aggregate concretes and recycled aggregate concretes are presented. Principles of interface design in the light of codes of practise: AASHTO-LRFD, ACI 318-19, EN 1992-1-1 and prEN 1992-1-1 were described. The theoretical predictions were compared with 184 results of experimental tests on push-off specimens. It has been found that most of the procedures allow for a safe estimation of the load carrying capacity of interfaces - with and without shear reinforcement. However, the obtained results were mostly conservative (depending on the considered design procedure, ratio of the experimental to theoretical load carrying capacity lies in range 1.51÷2.68). This may indicate that the description of shear transfer mechanism between concretes cast at different times is still imperfect and need to be improved.

PL

W artykule przedstawiono wybrane zagadnienia związane z nośnością styków pomiędzy betonami układanymi w różnym czasie. Konieczność zapewnienia właściwego zespolenia pomiędzy “starym” i “nowym” betonem zachodzi nie tylko w przypadku konstrukcji nowo wznoszonych, w których stosuje się elementy prefabrykowane, lecz także w obiektach już istniejących, gdy zachodzi potrzeba wzmocnienia konstrukcji. Tematyka nośności styków pomiędzy betonami układanymi w różnym czasie stanowi przedmiot badań eksperymentalnych prowadzonych od lat 60. ubiegłego wieku. Za pierwszy model opisujący zachowanie styków uznaje się teorię shear-friction, przedstawioną przez Masta i opisaną szczegółowo przez Birkelanda i Birkelanda. Model ten stosowany jest do dnia dzisiejszego w procedurach obliczeniowych ACI 318 i AASHTO-LRFD, jednak badania eksperymentalne prowadzone na przestrzeni lat wykazały potrzebę rewizji przyjętych założeń, polegających m.in. na uwzględnieniu sił adhezji czy kompozycji stosu okruchowego.