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1

A study on RCFST column instability modes

Lu Zhengran, Guo Chao

Archives of Civil Engineering

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2022

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Vol. 68, nr 2

211--225

EN

In this work, the instability damage modes of yield state of a steel tube at the tension side of a rectangular steel tube-confined concrete (RCFST) column under eccentric compression were classified into two types based on the coupling effect of slenderness ratio (λ) and eccentricity ratio (γ). The two types include the unilateral compression yield failure mode with a smaller value of γ and tensile and compressive yield failure modes on both column sides with a larger value of γ. Further, the parametric analyses were performed by employing the finite element (FE) method and the analytical analysis to test 16 groups of RCFST columns by varying the γ value with different λ values. It was observed that the results of the analysis for the mechanical properties like the responses of load-strain (Ρ-ε) and RCFST column instability modes correlated well with the results obtained in the experiments. Furthermore, the proposed theoretical method could be used to investigate the roles of γ as a controller against the instability in RCFST columns when compared with λ.

2

Modelling and assessment of a single pile subjected to lateral load

Abbas J. M., Chik Z., Taha M. R.

Studia Geotechnica et Mechanica

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2018

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Vol. 40, nr 1

65--78

EN

A three-dimensional finite element technique was used to analyse single pile lateral response subjected to pure lateral load. The main objective of this study is to assess the influence of the pile slenderness ratio on the lateral behaviour of single pile. The lateral single pile response in this assessment considered both lateral pile displacement and lateral soil resistance. As a result, modified p-y curves for lateral single pile response were improved when taking into account the influence lateral load magnitudes, pile cross sectional shape and flexural rigidity of the pile. The finite element method includes linear elastic, Mohr-Coulomb and 16-nodes interface models to represent the pile behaviour, soil performance and interface element, respectively. It can be concluded that the lateral pile deformation and lateral soil resistance because of the lateral load are always influenced by lateral load intensity and soil type as well as a pile slenderness ratio (L/D). The pile under an intermediate and large amount of loading (in case of cohesionless soil) has more resistance (low lateral displacement) than the pile embedded on the cohesion soil. In addition, it can be observed that the square-shaped pile is able to resist the load by about 30% more than the circular pile. On the other hand, pile in cohesionless soil was less affected by the change in EI compared with that in cohesive soil.

3

Large amplitude free vibration analysis of tapered Timoshenko beams using coupled displacement field method

Rajesh K., Saheb K. M.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 3

673--688

EN

Tapered beams are more efficient compared to uniform beams as they provide a better distribution of mass and strength and also meet special functional requirements in many engineering applications. In this paper, the linear and non-linear fundamental frequency parameter values of the tapered Timoshenko beams are evaluated by using the coupled displacement field (CDF) method and closed form expressions are derived in terms of frequency ratio as a function of slenderness ratio, taper ratio and maximum amplitude ratio for hinged-hinged and clamped-clamped beam boundary conditions. The effectiveness of the CDF method is brought out through the solution of the large amplitude free vibrations, in terms of fundamental frequency of tapered Timoshenko beams with axially immovable ends. The results obtained by the present CDF method are validated with the existing literature wherever possible.

4

Buckling stability assessment of plates under uniaxial compression

Riahi Farhad, Zirakian Tadeh, Ghaderi Vahed Mam, Arya Souran

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 2

97--105

EN

Buckling of thin-walled and load-bearing elements of a structure can have devastating consequences. Hence, buckling checks are an integral part of strength analysis of structures. The buckling problem of thin rectangular plates subjected to in-plane compressive and/or shear loading is of great importance in building, bridge, aerospace, marine, and shipbuilding industries. When buckling occurs, thin plates undergo large out-of-plane deflections, which in turn results in the development of large bending stresses and eventually complete failure of the structure. This paper deals with the buckling stability assessment of uniaxially-compressed plates with different support conditions within the framework of classical plate theory. The main objective of this research is to explore some uncovered aspects of buckling stability of plates by considering the effects of support conditions, aspect ratio, and slenderness ratio, which will consequently result in efficient design of such thin-walled structures. To this end, in addition to validation of the numerical simulation, some case studies have been performed in order to gain a better understanding of different aspects of buckling stability of such thin-walled structures.

5

Large amplitude free vibration analysis of tapered timoshenko hinged-hinged beam using coupled displacement field method

Korabathina R., Koppanati M. S.

Vibrations in Physical Systems

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2017

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Vol. 28

art. no. 2017007

EN

Tapered beams are more efficient compared to uniform beams as they provide a better distribution of mass and strength and also meet special functional requirements in many engineering applications like architecture, aeronautical, civil, mechanical, automobile, nuclear and robotics. The authors proposed a new method called Coupled Displacement Field (CDF) method in which the displacement field such as total rotation is assumed such that the assumed displacement must satisfy the kinematic and force boundary condition of the beam. The lateral transverse displacement is derived from the coupling equation which is derived from the static equilibrium conditions of the beam. By the application of principle of minimum total potential energy for different beam boundary conditions, the fundamental frequency parameter value is calculated in terms of taper ratio and slenderness ratio for various maximum amplitude ratios of the tapered Timoshenko shear flexible hinged-hinged beam boundary condition.

6

Experimental behaviour of steel tubular columns for varying in filled concrete

Sangeetha P., Senthil R.

Archives of Civil Engineering

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2017

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Vol. 63, nr 4

149--160

EN

This paper investigates the behaviour of axially-loaded tubular columns filled with M20 grade concrete and partially replaced concrete. The parameters varying in the study are slenderness ratio (13.27, 16.58 & 19.9), and normal M20 grade concrete, partially replaced quarry dust and concrete debris. The effects of the various concrete mixes and composite action between the steel tube and the concrete core are studied and a graph visualizing the differences between the load carrying capacity and the axial deflection is plotted. Some of the performance indices like the Ductility Index (DI), Concrete Contribution Ratio (CCR), Confinement Index (θ) and Strength Index (SI) are also evaluated and compared amongst the CFST columns. From the results it has been noted that an increase in the L/D ratio decrease the behaviour of the composite columns irrespective of the in filled materials. The composite action was achieved in the CFST columns filled with partially replaced quarry dust and concrete debris when compared with hollow steel columns. The load carrying capacity of the CFST column increases by 32 % compared with the hollow tubular columns.

PL

Stalowe słupy rurowe wypełnione betonem (CFST) są wykorzystywane do różnorodnych zastosowań, takich jak filary mostów, które są stale narażone na oddziaływanie ruchu ulicznego, słupy obsługujace zbiorniki magazynowe, pokłady kolejowe, pale oraz słupy stosowane w wysokich budynkach. Ze względu na zwiększone wykorzystanie tego rodzaju słupów zespolonych, zainteresowanie zachowaniem tego typu słupów przyczyniło się do przeprowadzenia wielu badań teoretycznych i eksperymentalnych. Chociaż słupy CFST nadają się do wykorzystania w wysokich budynkach na obszarach sejsmicznych, ich zastosowanie zostało ograniczone z powodu braku informacji o prawdziwej wytrzymałości i nieelastycznym zachowaniu CFST. Główną zaletą betonu w CFST jest to, że opóźnia on lokalne wyboczenie ściany rury i samego betonu, w umiarkowanym stanie, a zatem jest w stanie utrzymać większe obciążenia i naprężenia niż w stanie nieumiarkowanym. W niniejszej pracy zbadano zachowanie słupów rurowych obciążonych osiowo, wypełnionych betonem klasy M20 i częściowo zastąpionym betonem. Badaniu poddano łącznie 12 próbek, w celu zbadania zachowania stalowych słupów rurowych wypełnionych betonem przy różnym wypełnieniu. Parametry zróżnicowane w badaniu są współczynnikiem smukłości (13,27, 16,58 i 19,9) i betonem standardowej klasy M20, częściowo zastąpionym pyłem z kamieniołomu i odłamkami betonu. Badano wpływ różnych działań betonowych i kompozytowych w rurze stalowej i rdzeniu betonowym, a ponadto sporządzono wykres obciążenia i ugięcia osiowego. Niektóre wskaźniki wydajności, takie jak Wskaźnik Plastyczności (DI), Współczynnik Udziału Betonu (CCR), Wskaźnik Zamknięcia (θ) oraz Wskaźnik Wytrzymałości (SI) zostały również poddane ocenie i porównane z słupami CFST. Na podstawie wyników stwierdzono, że wzrost wskaźnika L/D ogranicza działanie słupów zespolonych, niezależnie od wypełnionych materiałów. Złożone działanie osiągnięto w słupach CFST wypełnionych częściowo wymienionym pyłem z kamieniołomu i odłamkami betonu, w porównaniu z pustymi stalowymi słupami. Wykorzystanie odłamków betonu i pyłu z kamieniołomu doprowadziło do poprawy zachowania konstrukcji słupów zespolonych poddanych obciążeniu osiowemu, w porównaniu do pustych stalowych słupów. Zwiększenie wytrzymałości w przypadku słupów CFST zależy od wytrzymałości na ściskanie wypełnionego betonu oraz od wskaźnika zamknięcia. Nośność słupa CFST wzrasta o 32% w porównaniu z pustymi słupami rurowymi, niezależnie od wypełnienia betonem. Wykorzystanie kruszywa pochodzącego z recyklingu w stalowych kolumnach rurowych jest nie tylko techniką utylizacji odpadów, lecz zmniejsza także koszt wypełnienia betonem.

7

Odkształcalność piaskowców w świetle zmian wilgotności i smukłości próbek

Bukowska M.

Przegląd Geologiczny

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2015

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Vol. 63, nr 10/3

1230--1236

EN

Natural humidity of rocks in the Upper Silesian Coal Basin results from the influence of mining activities and dewatering the rock mass. The state of humidity which best approximates laboratory rock tests to the conditions in the exploited rock mass is the capillary saturation state. Deformation properties of sandstones (Young’s modulus, post-peak failure modulus, critical strain, residual strain) were determined for samples of slenderness ratio of 1 and 2, which were loaded in a servo-controlled testing machine. In the samples of sandstones of different slenderness ratio, values of Young’s modulus decreased for the samples in dry-air condition and capillary saturation state. In the samples of rocks of different slenderness ratio, tested in the same state of humidity, an increase in the value of Young’s modulus was observed. The increase depends on grain size. Post-peak failure modulus of sandstones shows similar trends of changes depending on slenderness ratio, state of humidity of the samples and their grain size. In the conditions when the samples of sandstones of slenderness ratio of 1, were tested in two states of humidity, values of critical strain decreased by a few per cent. For the samples of greater slenderness ratio, which also were tested in two states of humidity there was an increase in the value of critical strain and in humidity. For the samples of slenderness ratio of 1 and 2 tested in dry-air condition and in capillary saturation state there was a decrease in the value of critical strain by a few tens percent. The trends of changes in values of residual strain are the same as of critical strain. Based on the conducted tests it was shown that humidity and slenderness ratio of the sandstone samples influence differently their deformability. Humidity has a greater influence on the value of Young’s modulus than slenderness ratio of the tested samples. For critical strain and residual strain it was demonstrated that slenderness ratio of the samples has a greater influence than humidity. Moreover, a greater influence of the value of residual strain, in comparison with the values of critical strain, was observed for sandstone samples of lower slenderness ratio.

8

Influence of support compliances on stability and limiting slenderness ratio of compression helical springs

Krużelecki J., Szubartowski D.

Journal of Theoretical and Applied Mechanics

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2014

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Vol. 52 nr 1

81--92

EN

In the paper, the influence of support compliances on the stability and the limiting slenderness ratio of compression helical springs was investigated. To analyze the stability of helical springs, the concept of an equivalent column was applied and a general system of supports described by three independent compliances was utilized. In the general case, the solution obtained, which describes the critical force, depends on two rotational compliances and a lateral compliance of a transverse shift of the support. The influence of the individual compliances on the critical load and on the limiting slenderness ratio was studied. Simple approximation formulas were proposed to describe these relationships.

9

Wpływ bezwładności obrotowej na rozkład obszarów inwestycyjnych niestateczności dynamicznej

Obara P.

Zeszyty Naukowe. Budownictwo / Politechnika Śląska

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2004

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z. 102

329-336

PL

W referacie, który jest kontynuacją referatu wygłoszonego na konferencji w 2003 roku [1], zostały przedstawione obszary rezonansu parametrycznego (niestateczności dynamicznej) pręta krępego poddanego działaniu zmiennej harmonicznie w czasie siły osiowej.

EN

When the shear strain and the rotational interia effect take into consideration, the parametric resonance areas decrease. The effects depend on the slenderness ratio (fig. 2), but for the prismatic rod it is not big. Larger effects could be expected for another applied section (for example - I-section).

10

Wpływ zawartości wody w ziarnie pszenicy i smukłości zbiornika na napór pionowy

Kusińska E.

Inżynieria Rolnicza

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2003

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R. 7, nr 8

227--234

PL

Przedstawiono wyniki badań naporu pionowego ziarna pszenicy o zawartości wody 0,136, 0,190 i 0,250 kg/kg s.m. na dno silosu o smukłości 10 oraz 16. Zastosowano czas przechowywania 20 dni. Udowodniono, że wybrane czynniki mają istotny wpływ na wartość naporu, który opisano za pomocą równań regresji.

EN

The study dealt with the vertical thrust of wheat grain layer of various moisture contents (0,136; 0,190; 0,250 kg/kg d.m.) on the bottom of silos of 10 and 16 slenderness ratios. The time of storage was 20 days. It was proved that selected factors significantly affected the thrust value what was described by regression equations.

11

Wpływ zawartości wody w ziarnach pszenicy i smukłości silosu na napór poziomy

Kusińska E.

Inżynieria Rolnicza

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2002

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R. 6, nr 9

149--156

PL

Przedstawiono wyniki badań naporu poziomego ziaren pszenicy o zawartości wody 0,136, 0,190 i 0,250 kg/kg s.m. na ściany silosu o smukłości 10 oraz 16. Zastosowano czas przechowywania 20 dni. Udowodniono, że wybrane czynniki mają istotny wpływ na wartość naporu, który opisano za pomocą równań regresji.

EN

Paper presented the investigation results concerning the side thrust of wheat grain of the moisture content (dry basis) 0.136, 0.190, 0.250 kg/kg DM, on the walls of a silo of slenderness ratio of 10 and 16. The storage duration was 20 days. It was proved the selected factors significantly affected the value of thrust what was described by regression equations.