Wyniki wyszukiwania - Biblioteka Nauki

1

Liniowe prawa tarcia warstwy ziarna zbóż

100%

Molenda M. , Horabik J.

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2002

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tom R. 6, nr 6

149--156

PL

Analizowano czynniki wpływające na tarcie ziarna zbóż. Stwierdzono, że zawartość wody, poziom naporu normalnego i procedura konsolidacji próbki wpływają istotnie na wyniki pomiaru współczynnika tarcia. Zależności naporu stycznego od naporu normalnego modelowano przebiegami liniowymi. Stwierdzono, że w zakresie zawartości wody 0,11-0,25 kg/kg i w zakresie naporu 20-100 kPa model liniowy bez wyrazu wolnego wystarczająco dokładnie opisuje tarcie ziarna pszenicy.

EN

Some factors affecting the friction of cereal grain were considered. Grain moisture content, the level of normal pressure and the procedure of sample consolidation were found to influence significantly the results of measuring friction coefficient. Linear relationship between frictional load and normal load were fitted to experimental results. The linear model without any free term was found to describe adequately the friction of wheat grain at the moisture content (dry basis) ranging from 0.11 to 0.25 kg/kg and the pressure range within 20-100 kPa.

2

Study of bearing capacity of skirted irregular pentagonal footings on different sands

100%

Thakur A. , Dutta R. K.

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tom Vol. 105, nr 1

5--17

EN

Purpose: The paper presents an experimental and numerical study to evaluate the bearing capacity of unskirted, singly and doubly skirted irregular pentagonal footings on different sands (S1, S2, S3) at a relative density of 30 %. The skirt depth of the footing was varied from 0.0B to 1.5B (B is the width of the square footing). Design/methodology/approach: The experimental and numerical study of the singly and doubly skirted irregular pentagonal footing resting on sands was modelled in a test tank and Plaxis 3D software respectively. Findings: The results of this study reveal that the bearing capacity was higher for the skirted irregular pentagonal footings on sand S3 followed by sand S2 and S1. The lowest percentage improvement for the singly skirted footing on sand S3 was 18.51% at a Ds/B = 0.25 whereas the highest improvement was 90.81% at a Ds/B = 1.50 for the singly skirted footing on sand S2. The highest percentage improvement for the doubly skirted footing on sand S2 was 95.13% at a Ds/B = 1.5 whereas the lowest improvement was 23.70% at a Ds/B = 0.25 the doubly skirted footing on sand S3. The results further revealed that the numerically obtained bearing capacity was marginally higher in comparison to the one obtained experimentally for the footings on all sands. Further, the experimental results validated the results obtained numerically with an average deviation of 8%. The percentage improvement in the bearing capacity was higher for the irregular pentagonal footing resting on sand S2 in comparison to sand S3 and S1. The settlement response of the irregular pentagonal footings is unchanged by increasing the number of elements beyond 7700. Both the experimental and numerical studies revealed a linear elastic behaviour at Ds = 0.5B, while the experimentally obtained pressure-settlement ratio plot shows a clear failure at Ds= 1B and 1.5B. Research limitations/implications: The results presented in this paper were based on the experimental and numerical study conducted on small scale model footings. However, for the actual footings, further study is recommended using full-scale field size footings to generalize the results. Originality/value: No experimental and numerical studies on singly and doubly skirted irregular pentagonal footings were conducted so far. Hence, an attempt was made in this article to predict the bearing capacity of these footings experimentally and using Plaxis 3D respectively.

3

Bearing capacity of E-shaped footing on layered sand

80%

Nazeer S. , Dutta R. K.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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tom Vol. 105, nr 2

49--60

EN

Purpose: The purpose of this study is to estimate the ultimate bearing capacity of the E-shaped footing resting on two layered sand using finite element method. The solution was implemented using ABACUS software. Design/methodology/approach: The numerical study of the ultimate bearing capacity of the E-shaped footing resting on layered sand and subjected to vertical load was carried out using finite element analysis. The layered sand was having an upper layer of loose sand of thickness H and lower layer was considered as dense sand of infinite depth. The various parameters varied were the friction angle of the upper (30° to 34°) and lower (42° to 46°) layer of sand as well as the thickness (0.5B, 2B and 4B) of the upper sand layer. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to decrease with the increased in the H/B ratio for all combinations of parameters. The dimensionless ultimate bearing capacity was maximum for the upper loose sand friction angle of 34° and lower dense sand friction angle of 46°. The results further reveal that the dimensionless bearing capacity of the E-shaped footing was higher in comparison to the dimensionless bearing capacity of the square footing on layered sand (loose over dense). The improvement in the ultimate bearing capacity for the E-shaped footing was observed in the range of 109.35% to 152.24%, 0.44% to 7.63% and 0.63% to 18.97% corresponding to H/B ratio of 0.5, 2 and 4 respectively. The lowest percentage improvement in the dimensionless bearing capacity for the E-shaped footing on layered sand was 0.44 % at a H/B = 2 whereas the highest improvement was 152.24 % at a H/B = 0.5. Change of footing shape from square to E-shaped, the failure mechanism changes from general shear to local shear failure. Research limitations/implications: The results presented in this paper were based on the numerical study conducted on E-shaped footing made out of a square footing of size 1.5 m x 1.5 m. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size E-shaped footing. Practical implications: The proposed numerical study can be useful for the architects designing similar types of super structures requiring similar shaped footings. Originality/value: No numerical study on E-shaped footing resting on layered sand (loose over dense) were conducted so far. Hence, an attempt was made in this article to estimate the bearing capacity of these footings.