Procter & Gamble (United Kingdom)
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Mogućnosti primene INSAR tehnologije za daljinsku detekciju deformacije geometrije puta
No full textPrimena satelitskih snimaka za daljinsku detekciju pomeranja zemljine kore prisutna je u naučnoj literaturi već više od dve decenije. Analiza je pokazala da takođe postoji mogućnost primene InSAR tehnologije, odnosno interferometrijskog radara sa sintetičkom blendom za ranu detekciju geodinamičkih procesa. Porastom broja javnih i komercijalnih satelita u Zemljinoj orbiti, dostupnost i učestalost prikupljanja potrebnih podataka značajno su porasli poslednjih godina. Sada je moguće prikupiti podatke u vremenskim rasponima od svega nekoliko dana za svaku tačku na
površini zemljine kore. Praćenje pomeranja infrastrukturnih objekata tradicionalnim geodetskim metodama je izuzetno skup i neefikasan proces. Sa druge strane, potreba za detekcijom i eventualnom predikcijom i prevencijom geoloških procesa u pojasu putne ili železničke infrastrukture nije upitna. Naučna saznanja u oblasti InSAR tehnologije dostigla su zrelost koja
opravdava njenu potencijalnu primenu u infrastrukturi. U okviru ovog rada napravljen je pregled uspešnih primena ove savremene tehnologije u saobraćajnoj infrastrukturi, kao i pregled različitih metoda prostorne i vremenske obrade interferometrijskih podataka. Konačno, izvršena je analiza pomeranja karakterističnih deonica državnih puteva u Srbiji
Geotechnical Conditions, Stability Analysis and Remedial Measures of Višnjička 74 Landslide in Belgrade
Get PDFThis paper presents the results of geotechnical investigations, stability analysis and urgent remedial measures of the landslide at Višnjička 74 street in Belgrade. The area under study is located at the foot of an old fossil landslide. The landslide was activated due to excavation of the foundation pit in June 2023. Due to large displacements of the retaining structures and the surrounding objects, urgent remedial measures were proposed. Following these measures, further sliding was prevented. Additional geotechnical investigations were performed (geophysical investigations, inclinometer measurements, boreholes, soil sampling, laboratory tests, piezometers), to obtain more comprehensive insight into the processes responsible for sliding. Residual shear parameters were determined by laboratory tests, and back calculated using numerical analysis and inclinometer readings. Very complex geotechnical conditions were determined on-site and thus presented in the light of future construction works
Geometric properties and idealized model of the Monument to the fallen soldiers of the Kosmaj detachment
No full textIn the territory of the former Yugoslavia, in the post-war period, numerous monumental sculptures, also referred to as "spomeniks" (monuments), were erected at various points, often in natural settings, to commemorate the People's Liberation War. Our focus in this paper is on one of them, the monument to the Kosmaj Partisan Detachment on mountain Kosmaj, near Belgrade. We examine the historical context in which the monument was created, directing the emphasis of the work towards the geometrical analysis of this object. We delve into the geometric elements of the monument, utilizing photogrammetry and descriptive geometry procedures. Through 'reverse engineering' based on the point cloud model and its orthogonal projections, we provide its idealized dimensions and plan.The 9th International Conference on Engineering Graphics and Design ICEGD 2024, 14-15 May 2024, Cluj Napoca, Romani
Načini ispitivanja cementnih kompozita ojačanih staklenom mrežicom kod zidanih konstrukcija
No full textPredmet rada je ispitivanje savremenog sistema za ojačanje zidanih konstrukcija poznatijeg pod nazivom FRCM (fiber reinforced cementitious matrix) koji se sastoji od staklene mrežice i malterske matrice. Sistem pogoduje zidanim konstrukcijama, jer ne menja značajno njihovu masu niti krutost, pri čemu povećava nosivost na određene uticaje i osigurava bolje ponašanje konstrukcije usled dejstva zemljotresa. U radu su date smernice i predlozi za unapređenje metodologije ispitivanja sličnih sistema, u cilju njihove primene za ojačanje zidanih konstrukcija
Connections between single elements made by 3D printed concrete
No full textThe 3D concrete printing (3DCP) technology as an innovative method of making concrete structures has already found application in contemporary construction works. The wider application has shown some obstacles, such as the lack of standards for design and production, the incorporation of reinforcement into the printing process, and underdeveloped load transfer systems. The motivation for this research come from the current practice in which the size of the printer usualy defines the size of the structure. Contrary to that, 3DCP technology can be considered as a part of updated method of prefabrication construction. Properly designed connections can create a robust structural system for adequate transfer of horizontal and vertical actions to the objects fundaments. The state of the art in the field of connections of 3DCP elements will be presented in this paper as well as the future experimental testings of seismic performance of segmental walls made of post-tensioned 3DCP elements under cyclic later load
Evaluation of yield surfaces' accuracy for steel I sections under elevated temperatures
No full textThe paper compares two approximative yield surface formulations with the “exact” yield surface
for the American wide flange W 4x426 steel cross-section, at room temperature and in different
fire scenarios. The first approximate yield surface is defined with a polynomial expression,
making its usage straightforward. The second yield surface is defined by Minkowski sum of
several ellipsoids, which makes it more complex. The exact yield surface is determined with the
fiber section with a fine discretization. The first step of a yield surface evaluation is thermal
analysis, as it is later necessary to reduce material characteristics due to heightened temperature.
The thermal analysis is carried out with the MATLAB transient thermal analysis solver. The
thermal material characteristics and the boundary coefficients of convective and radiative heat
transfer are defined according to EN 1991-1-2. Yield surfaces are compared, besides at room
temperature, for standard ISO 834 fire exposure of 30 and 45 minutes from three and four sides.
The comparison is done both graphically and numerically. The graphical comparison provides
an overview of regions in stress space that have the greatest deviations from the “exact” solution.
The numerical comparison, on the other hand, provides the overall error of the approximative
yield surface which is used to determine whether it is acceptable to use the yield surface. Results
from the comparison show that the polynomial yield surface has an allowable error and
deviations from the ”exact” yield surface at room temperature and in the case of four-side
heating. However, the error significantly rises for the case of three-side heating due to different
heating rates of flanges that cause plastic neutral axis shifting which can't be captured with the
proposed polynomial. Minkowski sum yield surface has acceptable errors and deviations in all
analyzed scenario
Mechanical buckling of FGM plates resting on elastic foundations using layer wise finite element
No full textThe concept of FGM was first introduced by a group of material scientists in Japan in mid–1980s for space plane project. FGMs are microscopically made composites usually from a mixture of metal and ceramic, in which material properties vary continuously in one or three directions. These gradual changes of materials properties overcome the disadvantages of traditional FRP (Fiber Reinforced Polymer) composites, regarding inter and intra laminar failure modes. The variation of material properties is defined by mathematical function, which may be given by: Power Law model, Exponential model, Sigmond law model, Mori Tanaka scheme and others. As FGMs are usually made of two materials, the metal and the ceramic, the ceramic layer serves for thermal resistance, whereas the metal layer gives high toughness. Due to the high heat resistance, FGMs have many practical applications in aerospace industries, defence industries, biomechanics, as well as and civil engineering. Therefore, the buckling problem of FGM plate subjected to in–plane loading and resting on elastic foundations received considerable interest of researchers over the last decades.
When modelling elastic foundations, many studies have been performed to predict the critical buckling loads of highway and airfield pavement systems as well as foundations of storage tanks, swimming pools, and buildings by employing a plate on an elastic foundation . The surface layer of the pavement (reinforced concrete slab in the rigid pavement and asphalt mixtures in the flexible pavement) is regularly simulated as a rectangular plate, while the underlying layers are modeled using an elastic foundation. For modelling elastic medium and describing the interactions of the plate and foundation, various kinds of foundation models are suggested. The simplest model for the elastic foundation is Winkler or one–parameter model [4], which models the foundation as a series of separated springs without coupling effects between each other. In wish to improve the Winkler model, several researchers tried to more realistically simulate interaction between the spring elements, by connecting upper ends of springs in the Winkler model with an elastic membrane or shear layer. These are so called the two–parameter foundations models, such as Filonenko–Borodich, Pasternak, generalized, and Vlasov.
In this study the mechanical buckling analysis of functionally graded plates resting on elastic foundation is modelled using two–parameter Pasternak model. The mathematical model, based on Layer wise theory of Reddy [9], assumes layer wise variation of in plane displacements and constant transverse displacement through the thickness, non–linear strain displacement relations (in von Karman sense) and isotropic non homogeneous material properties. The material properties of FGM plates are assumed to be constant in xy–plane and vary through the thickness by a power law function in terms of the volume fraction of the constituents. The effective materials properties are given by the rule of mixture. The principle of virtual displacement (PVD) is used to derive the weak form of linearized buckling problem. The weak form is discretized using nine node Lagrangian isoparametric finite element. The original MATLAB computer program is coded for the FEM solution. The influence of different parameters, such as elastic foundation parameters, in–plane load distribution, side–to–thickness ratio b/h, aspect ratio a/b and power–low index is presented. The accuracy of the numerical model is verified by comparison with the available results from the literature
Different profiled sheeting orientations in demountable shear connections
No full textReuse of building structures as an aspect of sustainable building construction provides
long-term benefits such as reduction of waste and carbon footprint. A demountable
shear connection with bolts and headed studs was proposed for application in reusable
steel-concrete composite floor structures. The effect of the profiled steel sheeting
orientation on the shear connection response was investigated through experimental
push-out tests and numerical FE simulations. The angle between the profiled sheeting
ribs and the supporting beam was varied in the range from 45° to 90°. Results
confirmed a non-negligible increase in the connection resistance with a rib-to-beam
angle decrease, which was analytically interpreted by proposing a design equation
Experimental and numerical investigation of CLT panels with different orientations of transverse layers
No full textThis paper presents an experimental and numerical investigation of two configurations of panels made of locally produced cross-laminated timber (CLT) with different orientations of laminations (boards) within transverse layers - conventional and modified orientation. Modified orientation refers to laminations of transverse layers positioned at an angle of ±45° in relation to longitudinal layers. The expected advantages of modified CLT are improved mechanical performance, more efficient use of resources considering material properties, reduction in variability of characteristics within the panels and increase in shear resistance. In addition to experimental testing, numerical analysis based on finite element method was performed and successfully validated in order to serve as a more efficient tool for CLT panel investigation and optimization
From independence tests to variable selection problems: Moving beyond Euclidean settings
No full textVariable screening procedures based on independence tests are considered. Special focus is placed on moving beyond the classical Euclidean setting, specifically to accommodate hyperspherical data among other types. Mixture data types are also considered. Extensive empirical studies indicate the robustness and adaptability of the proposed method to various high-dimensional structures