Wyniki wyszukiwania - Biblioteka Nauki

1

An experimental study on the shear strength of SFRC beams without stirrups

100%

Arslan G. , Keskin R. S. O. , Ulusoy S.

Journal of Theoretical and Applied Mechanics

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2017

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tom Vol. 55 nr 4

1205--1217

EN

The use of steel fibers in reinforced concrete (RC) structural members aims at the improvement of mechanical properties of such members. This study focuses on shear strength characteristics of steel fiber reinforced concrete (SFRC) beams without stirrups. Test specimens consisting of three RC and ten SFRC beams without stirrups have been tested under three-point loading in order to investigate the effects of fiber content and shear span-to-effective depth ratio on the shear strength. Furthermore, an equation developed previously for predicting the ultimate shear strength of SFRC beams without stirrups is proposed to predict the diagonal cracking strength of SFRC beams without stirrups.

2

Problem wyznaczania wytrzymałości na ścinanie gruntów przejściowych

100%

Radaszewski R. , Stefaniak K.

Przegląd Geologiczny

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2017

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tom Vol. 65, nr 10/2

864–872

EN

The paper deals with the issue of determining intermediate soil strength parameters. Particular attention has been drawn to a selected number of issues related to the examination of this type of soils, inter alia limited possibilities of collecting a high quality sample for laboratory tests along with selecting test procedures. Particular attention has been given to discrepancies between obtained results depending on the applied test procedure. The analysis covered test results of undrained shear strength (su) of normally consolidated soils of low plasticity, according to PN-ENISO 14688 soil types: saSi and clSi,from 3 testing grounds in the Poznań region. Laboratory tests were performed on samples of intact structure (NNS) in the triaxial apparatus (TXT) and direct shear apparatus (AB-2a). In the latter case, reconstituted samples were also analysed (PR). Field research was conducted using probes: static CPTUprobe and rotating PSO probe. The results, which require further confirmation, indicate that the adopted formula of working interpretations of CPTU probing results is of significant importance in assessing shear strength; Nkt coefficient in particular. The paper proposes modification of its most often used value into a value in which there was convergence of the results obtained with the use of both types of probes: CPTU and PSO. It was noted that velocity of applying shear stress has a significant impact on the final shear strength result. A possibility of using the PSO probe as a calibration test with reference to CPTU was suggested ifperforming the more advanced TXT test was not possible. It was also indicated that the test procedure in theAB-2a apparatus needed to be verify in order to obtain a tendency of shear strength changes comparable to the field studies. The results obtained confirm the need to prepare a repetitive canon of tests (test instructions) of intermediate soils that would enable adequate interpretation of their properties.

3

Shear performance of reinforced self-compacting concrete beams incorporating steel and polypropylene fibers

100%

Alkhattat S. S. , Al-Ramahee M. A.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2021

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tom Vol. 30, No. 4

537--551

EN

The impact of steel and polypropylene fibers on the performance of lightweight self-compacting concrete (LWSCC) beams was investigated in this study. Seven beams with various parameters were cast and tested. Partial (50%) and full (100%) replacement of coarse aggregate with lightweight aggregate expanded clay (LECA) were considered. In addition, a 1% volumetric ratio of steel or hybrid (steel and polypropylene) fiber was added to LWSCC beams to study their effect on the shear performance. The LWSCC beams had a decrease in ultimate load and stiffness of 23 and 30% for partial and full replacement, respectively when compared to normal weight beam. The addition of steel fiber improved the efficiency of LWSCC beams in terms of crack formation, failure mode, crack width, and ultimate load, as well as changed the failure mode from shear to flexure. The ultimate load for hybrid LWSCC was increased by around 6% for a partial replacement and 13% for full replacement as compared to beams without fibers. However, hybrid beams had a larger bearing capacity, little more cracks with smaller size, and ductile failure.

4

The influence of lap size on shear strength of adhesive joints

100%

Kubit A. , Ciecińska B. , Drozd K.

Advances in Science and Technology. Research Journal

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2015

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tom Vol. 9, nr 26

104--108

EN

Adhesive joints may be used instead of forced-in joints, welded and riveted joints, soldered and twisted connections. They are characterized by a lot of advantages, thanks to them the adhesive joints are willingly used in manufacturing processes. These advantages include low price of joint, reduction of weight of the final construction, improvement of durability, reliability and quality and improving visual appearance. From this point of view it should be concluded that experimental tests of adhesive joints are grounded. In the paper the results of experimental tests of static shear strength of singlelap joints are presented. These joints are made with two constructive glues. The specimens made from AISI 4130 steel were glued. Their surfaces were prepared in two versions before gluing: grinded with abrasive paper by hand and cleaned by sandblasting. The results were analyzed from variable size of the lap point of view.

5

Wymagania dotyczące połączeń międzywarstwowych nawierzchni dróg o niskim obciążeniu ruchem

100%

Malicki K.

Drogownictwo

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2015

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tom nr 1

10--14

PL

Artykuł ma na celu dyskusję zmian wymagań dotyczących wytrzymałości połączeń międzywarstwowych zaproponowanych w Polsce na przestrzeni ostatnich lat. W dyskusji wykorzystano wybrane wyniki badań wytrzymałości połączeń prezentowane w literaturze jak również wyniki własnych badań porównawczych. Istotnym wnioskiem płynącym z przeprowadzonych analiz jest konkluzja, iż objęcie wymaganiami nawierzchni dróg o wszystkich kategoriach obciążenia ruchem stanowi zagadnienie niezwykle ważne, również z punktu widzenia zarządców dróg powiatowych i gminnych.

EN

The paper is focused on the changes in shear strength requirements for asphalt interlayer bonding, proposed in Poland in last years. Selected test results chosen from the literature as well as from the own test results were considered. The main conclusion drawn from the work is, that covering the all types of roads with the requirements is really important, also for local road authorities.

6

Wpływ zagęszczenia i wilgotności na wytrzymałość na ścinanie wybranych odpadów paleniskowych

100%

Zydroń T. , Zawisza E. , Cieślik P.

Prace Naukowe Politechniki Warszawskiej. Inżynieria Środowiska

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2007

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tom z. 54

153-162

PL

Celem badań było określenie wpływu zagęszczenia i wilgotności wybranych odpadów paleniskowych na wartości parametrów charakteryzujących ich wytrzymałość na ścinanie. Badania wykonano w aparacie bezpośredniego ścinania o wymiarach skrzynki 120 x 120 x 97 mm z ramkami pośrednimi, tworzącymi strefę ścinania o grubości 10 mm odpowiadającej średnicy maksymalnego ziarna w badanym materiale. Dla określenia wpływu zagęszczenia i wilgotności na wartości parametrów wytrzymałościowych odpadów paleniskowych przeprowadzono dwie serie badań: - w pierwszej parametrem stałym był wskaźnik zagęszczenia Is= 0,90 lub 0,97, natomiast parametrem zmiennym była wilgotność wynosząca 0,6 wopt ; 0,8 wopt ; 1,0 wopt i 1,1 wopt , - w drugiej parametrem stałym była wilgotność materiału, wynosząca 0,6 wopt; 0,8 wopt; wopt lub 1,1 wopt, natomiast parametrem zmiennym był wskaźnik zagęszczenia Ig = 0,90; 0,94; 0,97 i 1,00.

EN

Determination of the influence of cornpaction and moisture content of chosen fly ashes on the values of the parameters describing their shear strength was the aim of the tests. They were carried out in a di-rect shear apparatus in a case of dimensions of 120 x 120 x 97 mm with intermediate frames, forming a shearing zone of the height of 10 mm, corresponding to the diameter of the greatest grain in the material tested. Two series of tests were carried out to determine the influence of compaction and moisture content on the values of strength parameters of fly ashes: - in the first series degree of compaction Is= 0.90 or 0.97 was constant, whereas the moisture content changed and was equal 0.6 wopt ; 0.8 wopt ; 1.0 wopt and 1.1 wopt, - in the second series moisture content equal 0.6 wopt ; 0.8 wopt ; 1.0 wopt or 1.1 wopt was constant and degree of compaction changed and was equal 0.90; 0.94; 0.97 and 1.00.

7

Bonding of birch solid wood of sawmill surface roughness with use of selected thermoplastic biopolymers

100%

Gumowska A. , Kowaluk G.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2019

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tom No. 106

9--15

EN

Bonding of birch solid wood of sawmill surface roughness with use of selected thermoplastic biopolymers. The aim of the research was to determine the shear strength and in-wood damage share of the birch lamellas of the surface shaped by rotary saw cutting and bonded with use of selected thermoplastic biopolymers, like polylactide (PLA) and polycaprolactone (PCL), as well as with use of polypropylene (PP) as a reference bonding material. The results show that the highest mechanical properties have been achieved in case of PLA used as a binder.

PL

Łączenie drewna brzozy o chropowatości drewna tartacznego z wykorzystaniem wybranych biopolimerów termoplastycznych. Celem badań było określenie wytrzymałości na ścinanie i udziału zniszczenia w drewnie lameli brzozowych o powierzchniach ukształtowanych na pilarce tarczowej i sklejonych przy użyciu wybranych biopolimerów termoplastycznych, takich jak polilaktyd (PLA) i polikaprolakton (PCL), jak również z zastosowaniem polipropylenu (PP) jako referencyjnego materiału wiążącego. Badania wykazały najwyższą przydatność PLA do łączenia litego drewna brzozy, podczas gdy pozostałe wykorzystane w badaniach polimery dawały spoinę o niższych od wspomnianego polimeru wytrzymałości.

8

Shear performance of reinforced self-compacting concrete beams incorporating steel and polypropylene fibers

100%

Alkhattat S. S. , Al-Ramahee M. A.

Przegląd Naukowy. Inżynieria i Kształtowanie Środowiska

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2021

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tom 30

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nr 4[94]

9

The influence of moisture content on shear strength of cohesive soils from the landslide area around Gorlice

100%

Zydroń T. , Dąbrowska J.

AGH Journal of Mining and Geoengineering

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2012

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tom Vol. 36, no. 2

309-317

EN

In this paper shear strength test results of soils from the surface layers of landslide slopes from Bystra and Siary by Gorlice are presented. The main purpose of this work was to determine the influence of moisture content and shear velocity on the values of shear strength as well as to determine Matsushi-Matsukury's formula's usability for describing shear strength. Tests were carried out in standard direct shear box apparatus, on 60x60x20 mm samples, where additional boxes in transitional frames were placed between to minimize the interlocking, which can occur during shearing. The soil tests were carried out on five samples that had different moisture contents. Three shear velocities were used: 0,1; 1,0 i 10 mm x min-1. Relations derived from tests carried out indicate that the higher the shear velocity, the graeter the influence of moisture content on values of the angle of internal friction and cohesion. Values of soil resistance calculated using Matsushi-Matsukury's equation are basically concurrent with measured results, however, results of low values of soil resistance, which concerned samples with high moisture content, show better matching.

PL

W pracy przestawiono wyniki badań wytrzymałości na ścinanie gruntów pochodzących z powierzchniowych warstw zboczy osuwiskowych w Bystrej i Siarach k. Gorlic. Podstawowym celem pracy było określenie wpływu wilgotności badanych gruntów i prędkości ścinania na ich wytrzymałość na ścinanie oraz określenie przydatności formuły Matsushi-Matsukury do opisu ich wytrzymałości. Badania przeprowadzono w standardowym aparacie bezpośredniego ścinania na próbkach o wymiarach 60x60x20 mm, gdzie dodatkowo pomiędzy skrzynkami umieszczono ramki pośrednie dla wyeliminowania zjawiska zazębiania się ziaren gruntu w trakcie ścinania. W przypadku każdego gruntu badania przeprowadzono na próbkach o pięciu wartościach jego uwilgotnienia. Zastosowano trzy prędkości ścinania 0,1; 1,0 i 10 mm x min-1. Otrzymane z badań zależności wykazały, że im większa prędkość ścinania, tym większy jest wpływ uwilgotnienia na wartości kąta tarcia wewnętrznego i spójności gruntów. Z kolei wartości oporu na ścinanie uzyskane na podstawie wzoru Matsushi-Matsukury były zasadniczo zbieżne z wynikami bezpośrednich badań, przy czym lepsze dopasowanie wykazały wyniki odpowiadające niskim wartościom oporu na ścinanie.

10

Shear and crushing strengths of wood pellets

100%

Spirchez C. , Lunguleasa A.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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tom vol. 59, nr 198

87--97

EN

This paper presents a methodology for determining the shear and crushing strengths of four types of wood pellets. Wood pellets are renewable and sustainable products that are obtained from wood biomass and used in combustion. Their mechanical characteristics are not well defined. To characterize wood pellets, their shear and crushing strengths should be measured along with their size, moisture content, density, abrasion, and chemical contents. The shear and crushing strengths were analysed for their dependence on density, considering if these strengths remain as independent properties or only an additional option for the producers. All results showed that the shear and crushing strengths were individual properties of wood pellets and that density greatly influenced these properties. Based on theoretical research, the admittance values of breaking and shear strengths were also estimated. These results can be used in wood combustion for creating fuels from waste wood.

11

Assessment of shear strength in silty soils

100%

Stefaniak K.

Studia Geotechnica et Mechanica

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2015

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tom Vol. 37, nr 2

51--55

EN

The article presents a comparison of shear strength values in silty soils from the area of Poznań, determined based on selected Nkt values recommended in literature, with values of shear strength established on the basis of Nkt values recommended by the author. Analysed silty soils are characterized by the carbonate cementation zone, which made it possible to compare selected empirical coefficients both in normally consolidated and overconsolidated soils.

12

Impact of a Test Method on the Undrained Shear Strength of a Chosen Fly Ash

100%

Gruchot A. , Zydroń T.

Journal of Ecological Engineering

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2016

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tom Vol. 17, nr 4

41--49

EN

The paper presents an assessment of the suitability of a laboratory vane apparatus, a cone penetrometer as well as a shear vane tester and a pocket penetrometer for determination of the parameters of the undrained shear strength of fly ash from the Power Plant “Skawina”. The suitability of the cone penetrometer and the laboratory vane apparatus for the determination of the undrained shear strength of the fly ash has been shown. On the bases of the obtained test results, , drained and undrained shear strengths of the subsoil made of the fly ash under the square pad foundation were calculated according to Eurocode 7. The calculations of the ultimate resistance of the drained subsoil showed that it was several times bigger than its value in undrained conditions. This confirms the need for the proper determination of the angle of internal friction and cohesion as well as the undrained shear strength of fly ashes.

13

Effect of hydrogen on adhesion of stainless steel to structural steel in explobond clad plates

88%

Lubińska K. , Szummer A. , Szpila K. , Kurzydłowski K. J.

Advances in Materials Science

|

2007

|

tom Vol. 7, nr 1(11)

147-152

EN

Clad plates are usually made of carbon or law alloy steel plates with a thinner layer of stainless steels which offer resistance to different corrosive environments containing hydrogen, in diverse industries like chemical, offshore, petrochemical, petro-leum refineries, nuclear, etc. It is well known that hydrogen deteriorates structure and properties of stainless steels and law alloy steels as well. In the case of clad steels, hydrogen may induce underclad cracking. In this work the results are presented of the study of the influence of hydrogen on adhesion of austenitic stainless steel to the law alloy steel in explobond clad plates. Specimens were destructively tested in band shear test. Light and scanning electron microscopy were used for examination of the shear fracture surface. It was shown that hydrogen significantly lowers a shear strength of bonding between austenitic stainless steel flyer and parent law alloy steel.

14

Characteristics of Die-Attach Method by Sinter Bonding Using Ag-40Cu Mechanically Alloyed Particles

88%

Choi W. L. , Lee J.-H.

Archives of Metallurgy and Materials

|

2019

|

tom Vol. 64, iss. 2

507--512

EN

Ag and Cu powders were mechanically alloyed using high-energy planetary milling to evaluate the sinter-bonding characteristics of a die-attach paste containing particles of these two representative conductive metals mixed at atomic scale. This resulted in the formation of completely alloyed Ag-40Cu particles of 9.5 μm average size after 3 h. The alloyed particles exhibited antioxidation properties during heating to 225°C in air; the combination of high pressure and long bonding time at 225°C enhanced the shear strength of the chip bonded using the particles. Consequently, the chips sinter-bonded at 225°C and 10 MPa for 10 min exhibited a sufficient strength of 15.3 MPa. However, an increase in bonding temperature to 250°C was detrimental to the strength, due to excessive oxidation of the alloyed particles. The mechanically alloyed phase in the particle began to decompose into nanoscale Ag and Cu phases above a bonding temperature of 225°C during heating.

15

Influence of the heterogeneity of a dump soil on the assessment of its selected properties

88%

Olesiak S.

Studia Geotechnica et Mechanica

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2020

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tom Vol. 42, nr 3

263--275

EN

This article concerns the assessment of selected physical and mechanical properties of a dump soil. The dump soil is a specific soil with a very heterogeneous internal structure. Next to each other, there may be lumps and crumbs of cohesive soils mixed with non-cohesive soils accompanied by a very diverse admixture of organic substance. In addition, the soil in the waste dump, in spatial terms, may significantly differ in consistency and density. This is the result of the process of forming a dump soil, which takes place in three stages: excavation, transport and dumping. A heterogeneous soil deposited within the waste dump is subject to further processes: consolidation, compaction and creeping. Changes occurring in the course of these processes have a significant impact on the development of the properties of the dump soil. Due to the large diversity of the tested soils, the results of their properties were divided into two groups, based on type and consistency of soil. This allows us to estimate the selected properties of the dump soil only on the basis of their macroscopic analysis.

16

Experimental study on earth pressure reduction of waste tyre bales used as a backfill for rigid retaining structures

88%

Duda A. , Siwowski T.

Studia Geotechnica et Mechanica

|

2021

|

tom Vol. 43, nr 4

411-424

EN

Waste tyre-derived products, including whole tyres, tyre bales, shreds, chips and crumb rubber, have been widely used in geotechnical applications. In particular, tyre bales have considerable potential for use in the construction of a lightweight embankment or road foundation over soft ground, slope stabilisation or landslide repairs and the backfilling for retaining structures. Proper design of tyre bale structures requires a reliable strength analysis to ensure an adequate factor of safety. The analysis should utilise the properties of the tyre bales and the baled structures, which must be properly determined. A laboratory test programme was developed to determine the key strength parameters of a backfill made of tyre bales supplemented with a lightweight aggregate. Full-scale direct shear tests were conducted to define the interface shear strength between the tyre bales and the filling material. Earth pressure reduction analysis based on the experimental results was performed as well to assess the effectiveness of waste tyre bales used as a backfill for rigid retaining structures.

17

X-ray microtomography (μCT) as a useful tool for visualization and interpretation of shear strength test results

88%

Stefaniuk D. , Tankiewicz M. , Stróżyk J.

Studia Geotechnica et Mechanica

|

2014

|

tom Vol. 36, nr 4

47--55

EN

The paper demonstrates the applicability of X-ray microtomography (μCT) to analysis of the results of shear strength examinations of clayey soils. The method of X-ray three-dimensional imaging offers new possibilities in soil testing. The work focuses on a non-destructive method of evaluation of specimen quality used in shear tests and mechanical behavior of soil. The paper presents the results of examination of 4 selected clayey soils. Specimens prepared for the triaxial test have been scanned using μCT before and after the triaxial compression tests. The shear strength parameters of the soils have been estimated. Changes in soil structure caused by compression and shear failure have been presented as visualizations of the samples tested. This allowed for improved interpretation and evaluation of soil strength parameters and recognition of pre-existing fissures and the exact mode of failure. Basic geometrical parameters have been determined for selected cross-sections of specimens after failure. The test results indicate the utility of the method applied in soil testing.

18

Epoxy adhesive formulations using latent imidazole metal cation complexes

88%

Pilawka R. , Maka H.

Polish Journal of Chemical Technology

|

2011

|

tom 13

|

nr 1

63-66

EN

Complexes of 2-methylimidazole with cations from several metal sulfates were prepared and investigated as curing agents for epoxy resins. The reactivity of one-part formulations of these complexes with a bisphenol A type epoxy resin was determined by the differential scanning calorimetry and the pot life observed by viscosity measurements. Tensile lap shear tests at room temperature and at 120°C were used to evaluate the adhesive strength of the formulations directly after preparation as well as after one and three months of storage at room temperature.The DSC measurements showed much lower reactivity (7 - 32%) and higher reaction temperatures of the complex formulations in comparison to the mixtures with pure 2-methylimidazole. The viscosity of most formulations remained almost unchanged over the observed period of three months. The adhesive strength of the freshly prepared complex formulations is comparable to a formulation with pure 2-methylimidazole and decreases over time, depending on the type of metal cation and the cation-to-imidazole molar ratio. The obtained results indicate that complexes of 2-methylimidazole with cations are suitable as latent curing agents for epoxy resins.

19

The use of dilatometer test for the determination of undrained shear strength in organic soils

88%

Rabarijoely S.

Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation

|

2008

|

tom 40

20

A note on the differences between Drucker-Prager and Mohr-Coulomb shear strength criteria

88%

Wojciechowski M.

Studia Geotechnica et Mechanica

|

2018

|

tom Vol. 40, nr 3

163--169

EN

A systematic approach to measure the differences between Mohr-Coulomb (MC) and Drucker-Prager (DP) shear strength criteria used commonly in soil and rock mechanics is presented. It is shown that the DP criterion generates a shear strength between 0.6 and 3 times the MC strength, for the same friction angle and cohesion parameters. The appropriate conditions for obtaining equal shear strengths are given. Moreover, some new DP failure surfaces are proposed which minimize the differences relative to the MC predictions. The equivalence of the DP and MC criteria under plane strain conditions is also examined.