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1

The Effect of Soil-Structure Interaction (SSI) on Structural Stability and Sustainability of RC Structures

Krishnan Ragi, Sivakumar Vidhya Lakshmi

Civil and Environmental Engineering Reports

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2024

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Vol. 34, no. 1

116--136

EN

The issue of SSI involves how the ground or soil reacts to a building built on top of it. Both the character of the structure and the nature of the soil have an impact on the stresses that exist between them, which in turn affects how the structure and soil beneath it move. The issue is crucial, particularly in earthquake regions. The interaction between soil and structure is an extremely intriguing factor in increasing or reducing structural damage or movement. Structures sitting on deformable soil as opposed to strong soil will experience an increase in static settlement and a decrease in seismic harm. The engineer must take into account that the soil liquefaction problem occurs for soft ground in seismic areas. A reinforced concrete wall-frame dual framework's dynamic reaction to SSI has not been sufficiently studied and is infrequently taken into consideration in engineering practice. The structures’ seismic performance when SSI effects are taken into account is still unknown, and there are still some misconceptions about the SSI idea, especially regarding RC wall-frame dual systems. The simulation study of the soil beneath the foundations significantly impacts the framework's frequency response and dynamic properties. Therefore, the overall significance of SSI in the structural aspect and sustainability aspects will be reviewed in this research.

2

Nonlocal strain gradient-based nonlinear in-plane thermomechanical stability of FG multilayer micro/nano-arches

Yang Zhicheng, Hurdoganoglu Dogus, Sahmani Saeid, Nuhu Abubakar Abdussalam, Safaei Babak

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e90, 2023

EN

In various microelectromechanical systems, arch-type micro- or nanostructures are extensively used because of their specific geometry. In this regard, the present research exploration deals with the size-dependent nonlinear in-plane stability characteristics of functionally graded (FG) multilayer composite micro/nano-arches subjected to uniform radial pressure together with temperature changes. To this intension, the nonlocal strain gradient (NSG) continuum elasticity is implemented in a higher-order shear flexible arch model to capture nonlocal stress tensor as well as strain gradient size dependencies. With the aid of the Halpin-Tsai homogenization scheme, the material the effective Young’s modulus is extracted layer to layer corresponding to different FG multilayer pattern of composite micro/nano-arches. The NSG-based radial load-defection and radial load-axial load nonlinear equilibrium paths are traced corresponding to several parametrical case studies. It is revealed that the both effects of the nonlocal stress tensor and strain gradient size dependency on the value of lower and upper limit radial pressures are more signifcant than those on the lower and upper limit resultant axial forces. Furthermore, it is observed that by increasing the value of temperature change, the effects of nonlocality and strain gradient size dependency on the NSG-based lower limit radial pressure enhance, while these efects on the NSG-based lower limit resultant axial force decrease.

3

The analysis of buckling and post buckling in the compressed composite columns

Wysmulski P.

Archives of Materials Science and Engineering

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2017

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Vol. 85, nr 1

35--41

EN

Purpose: The aim of the study was to analyse the work of a thin-walled C-shaped profile, made of a carbon-epoxy composite, which was subjected to unified axial compression. Design/methodology/approach: The scope of the study included the analysis of the critical and low post-critical state by the use of numerical and experimental methods. As a result of the experimental test, performed on the physical specimen, post-critical equilibrium path had been determined, on the basis of which, with use of the adequate approximation method critical load value was defined. The next stage of the research was devoted to numerical analysis based on the finite element method. The studies were carried out on a scope of the linear analysis of the eigenvalue problem, on the basis of witch the critical value of load for mathematical model was found. The next step of the numerical tests was covering the nonlinear analysis of the low post-critical state for the model with geometrical imperfection, corresponding to the lowest form of buckling. Findings: The result of the study was to determine the value of the critical load, on the basis of the experimentally obtained post-critical equilibrium paths of the structure, with use of two independent methods of Approximation: Koiter's method and the method of the vertical tangent. The results of the analysis were compared with the value of the critical load determined by using finite element method. Research limitations/implications: The obtained results of study provide the important information concerning the modelling techniques of the thin-walled structures made of composite materials, while confirming the adequacy of the numerical models developed both in the calculation of eigenvalue problem, as well as non-linear static analysis in the post-critical range. Originality/value: The research provided the necessary knowledge of the behaviour of the critical and low post-critical of the thin-walled structure made of modern orthotropic material (CFRP).

4

Geomechanic study regarding the stability of the surface mining constructions belonging to the mining perimeter of Certej

Arad V., Arad S., Cosma V.

Cuprum : czasopismo naukowo-techniczne górnictwa rud

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2015

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nr 4

41--49

EN

Within the context of the extended economic crisis, as a whole, gold and silver ores are now largely paid attention to by investors. In Romania, they have carried out, during the last years, a large number of researches regarding the prospection and planning of the exploitation of new Au-Ag ore deposits. The University of Petrosani, owing to its Laboratory of Rocks Mechanics, largely contributed to such research works, through the geomechanical analyses gathered from the mining areas of the “Golden Quadrangle” in the Apuseni Mountains. This paper presents the results of these geomechanical studies made in perimeters mentioned. The hereby paper displays conclusions determined by the geotechnical researches of the mining perimeter of Certej, performed in the Geomechanics Laboratory of the University of Petrosani, with a view to opening and exploiting the gold and silver deposit as part of a new mining project.

PL

W kontekście długotrwałego ekonomicznego kryzysu, uwagę inwestorów przykuwają głównie rudy złota i srebra. W Rumunii przeprowadzili oni w ciągu ostatnich lat wiele badań z zakresu prospekcji i planowania eksploatacji nowych złóż Au-Ag. Uniwersytet Petrosani, dzięki swojemu Laboratorium Mechaniki Skał, miał znaczny udział w tych badaniach, wykonując analizy geomechaniczne na próbach z rejonów górniczych „Złotego Czworokąta” w górach Apuseni. Niniejszy artykuł przedstawia wyniki badań geomechanicznych dotyczących ww. rejonu. Prezentuje wnioski z badań geotechników z rejonu Certej, przeprowadzonych w Laboratorium Geomechaniki Uniwersytetu Petrosani, z perspektywy rozpoczęcia nowego projektu eksploatacji złoża złota i srebra.

5

Optimum weight design of multilayered fiber composite plates with discrete ply angles and uncertainty in ply thicknesses

Latalski J.

Composites Theory and Practice

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2014

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R. 14, nr 4

183--188

EN

The presented paper discusses the minimum weight design of multilayered fiber composite plates with tolerances in individual ply thicknesses. These tolerances are given by the maximum acceptable deviation of every individual ply thickness from its nominal value. The robustness of the design is achieved by diminishing the design state variable (buckling load factor) by the product of arbitrary assumed tolerances and appropriate sensitivities. The proposed approach is illustrated with examples of a simply supported rectangular laminated plate design under uni- and bi-axial compression. The minimum weight identified by the total number of layers is found to assure plate stability. For the discussed analysis, buckling load sensitivity formulas with respect to ply thicknesses are given. Based on these relations, the impact of the discussed variations on the optimal laminate stacking sequence and buckling mode shape is studied in detail. The achieved results emphasize the importance of robust design opposed to merely nominal approaches.

PL

Przedstawiono zagadnienie optymalizacji wielowarstwowych płyt kompozytowych z włóknami ukierunkowanymi dyskretnie z uwzględnieniem występowania tolerancji grubości poszczególnych lamin. Rozważane tolerancje zostały zdefiniowane jako maksymalne dopuszczalne odchylenia rzeczywistej grubości każdej z warstw od jej wartości nominalnej. W zaproponowanym podejściu do zagadnienia rozwiązanie optymalne uzyskano poprzez zmniejszenie zmiennej stanu zadania o wartość iloczynu przyjętych arbitralnie tolerancji i odpowiednich wrażliwości tej zmiennej stanu. Metodę rozwiązania zilustrowano przykładami ściskania jedno- i dwuosiowego płyty prostokątnej, swobodnie podpartej czterostronnie. Jako kryterium optymalizacji przyjęto minimum ciężaru (grubości) płyty. Zapisano rekurencyjne zależności na wrażliwość siły krytycznej względem grubości poszczególnych warstw laminatu. Następnie, na podstawie tych zależności, wyznaczono zmodyfikowaną wartość siły krytycznej obciążenia. Szczegółowo omówiono wpływ badanych tolerancji na układ i kolejność warstw w laminacie wielowarstwowym. Uzyskane wyniki w pełni potwierdzają zasadność stosowania optymalizacji odpornościowej jako metody projektowania gwarantującej lepsze (bezpieczniejsze) rozwiązania niż standardowe ujęcie nominalne zagadnienia.

6

The investigation of stability of double-layer octahedron-based geodesic domes

Bysiec D.

Structure and Environment

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2011

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Vol. 3, no. 3

30-41

EN

The paper presents the investigation of stability of two double-layer octahedron-based geodesic domes. The stability analysis includes the forces acting in the bars as well as the displacements of the nodes with a static point load of 10 kN applied to the top symmetrical node. The investigation was conducted with both identical constant cross-section of all the bars and variable cross-sections (with their adjustment to the internal forces) in each of the bar groups. Moreover, diagrams illustrating the rates of change of the values of the forces and displacements were presented. Also the limit values were determined, above which the analysed structures are unstable.