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1.
CALIBRATION OF A NEW METHOD FOR CREATING IMPERFECTIONS ON SLENDER STRUCTURES
Simon Hudales, 2022, magistrsko delo

Opis: For the design of slender structures consisting of plates and tubes, such as supporting structures at cranes, buckling is beside stress and fatigue often the governing failure criteria. Stability analysis of such structures is usually performed using the GMNIA method according to DIN EN 1993. For this purpose, a suitable geometric equivalent imperfection must be applied to the structure. Buckling inherent shapes are determined for this purpose and scaled according to applicable safety concepts. Including imperfections in stability analysis can generally be relevant for the load-bearing behavior of a structure. Within this master thesis work, the influence of the initial geometric imperfection on stability behaviour is investigated. This study examines the influence, that imperfections imposed on members subjected to tensile stress have on stability behaviour. Tensile members of structures are identified and initial geometric imperfection is imposed on them in addition to critical members, that are subjected to compression stress. It is shown, that including imperfections on tensile members in stability analysis, has only a minor influence on stability behaviour and stiffness of the structure, both reducing it just slightly. Further on, investigation on boom model, that is supporting structure of the crawler crane, is made. Boom model consist of main chord members and diagonals connecting them. At the joint connection of boom and two diagonal members, one subjected to tension and one subjected to compression stress, appears area of high shear stresses. Influence of the direction, that imperfection is imposed on the diagonal member, and what is the influence on the stability behaviour and structural strength is presented in this work. Most severe case of the two chosen direction is pointed out and discussed.
Ključne besede: stability analysis, initial geometric imperfections, thin-walled structures, finite element method
Objavljeno v DKUM: 06.07.2022; Ogledov: 143; Prenosov: 33
.pdf Celotno besedilo (5,14 MB)

2.
Retaining structure in demanding ground conditions: PK-16, road Hrastnik - Zidani Most : master's thesis
Aleksandr Sokolov, 2021, magistrsko delo

Opis: The master thesis presents the findings of the review of the design documentation of PGD plans for the PK-16 retaining structure, reconstruction of the G2-108 Hrastnik - Zidani Most road and deviation of the G1-5 Rimske Toplice - Zidani Most - Radeče road. The PK 16 retaining structure is foreseen between the Sava riverbed and the new road. The length of the retaining structure is substaintal (approx. 1140 m), the morphology of the terrain along the wall varies greatly. However, due to the erosion of the Sava River, it is estimated that the wall will need to be deep or corrosion protection should be constructed. Temporary security and work platforms based on the Sava River Basin (which is already impounded and quite deep in this part) will be required. The retaining structure is designed as a vertical cantilever wall that is on the underside rigidly fixed to the horizontal foundation plate. On the bulk of the structure, the foundation plate is supported by piles in two rows. The vertical wall at the top passes into a horizontal cantilever along which a corridor with a fringe runs. The controlling calculations were done employing a computational 2D model that takes into account the elastoplastic Mohr - Coulomb model for soil and the elastic model of concrete structures. The accompanying geotechnical calculations of the retaining structure in profiles P283 and P299 were compared with the analyses made in the design project to confirm the possibility of carrying out the proposed structures.
Ključne besede: civil engineering, geotechnical design, retaining structures, cantilever walls, piles
Objavljeno v DKUM: 13.10.2021; Ogledov: 382; Prenosov: 31
.pdf Celotno besedilo (2,99 MB)

3.
Modeliranje in armiranje prekladnih elementov mostnih konstrukcij s programom Tekla Structures : diplomsko delo
David Tomaž, 2021, diplomsko delo

Opis: Diplomsko delo obravnava možnosti uporabe programa Tekla Structures, Rhino in Grasshopper pri modeliranju, armiranju in izdelavi armaturnih risb na realnih primerih prekladnih mostnih konstrukcij Viadukta Pesnice ter Mostu čez Savo v Krškem, ki je zahtevnejše oblike. V diplomskem delu je najprej predstavljen princip delovanja programov Tekla Structures, Rhino in Grasshoper, nato pa prikazan postopek modeliranja in armiranja ter izdelave armaturnih risb v programu Tekla Structures.
Ključne besede: modeliranje, armiranje, mostovi, Tekla Structures, Rhino, Grasshopper
Objavljeno v DKUM: 07.10.2021; Ogledov: 480; Prenosov: 77
.pdf Celotno besedilo (8,96 MB)

4.
A three-dimensional static numerical model of a complex underground structure in high squeezing ground
Tina Marolt Čebašek, Jakob Likar, 2015, izvirni znanstveni članek

Opis: The present study assesses high squeezing ground confirmed by empirical and semi-empirical theories. High squeezing ground is often present in underground constructions at great depths, but it is hardly ever researched separately from light and fair squeezing ground. A three-dimensional, static numerical model is developed for a complex underground structure consisting of a shaft, a silo, and a mine roadway at great depth, which is certainly in high squeezing ground. Furthermore, a solution for the entire structure based on shotcrete with incorporated yielding elements is provided. The yielding elements, in general, absorb the strain energy by compressing at a relatively constant stress, but without rebounding. A three-dimensional, static numerical model of a support system with incorporated yielding elements is established in order to demonstrate that the presented forces are under control. Therefore, a failure of the lining is avoided because the stresses in the shotcrete lining are below its load-bearing capacity. It can be concluded that yielding elements incorporated in the shotcrete lining play an important role in the support solution in high squeezing ground.
Ključne besede: high squeezing ground, numerical model, underground structures, deformations, yielding support element
Objavljeno v DKUM: 14.06.2018; Ogledov: 778; Prenosov: 67
.pdf Celotno besedilo (606,20 KB)
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5.
Ground-sourced energy wells for heating and cooling of buildings
Heinz Brandl, Dietmar Adam, Roman Markiewicz, 2006, izvirni znanstveni članek

Opis: Energy wells are thermo-active elements for an economical extraction or storage of ground energy, similar to energy piles and other deep foundation elements also used as heat exchangers. Heating and/or cooling of buildings requires a primary and secondary thermo-active circuit, commonly connected by a heat pump. The paper gives several design aspects of energy wells which can be also used for the design of deep energy foundations. Thermal response tests have proved suitable for the in-situ determination of thermal ground properties required for an optimised design. Moreover, different systems of energy wells are discussed, and a comprehensive pilot research project is described.
Ključne besede: energy wells, energy foundations, geothermal geotechnics, geothermal heating/cooling, thermo-active structures, thermal ground properties, field testing
Objavljeno v DKUM: 17.05.2018; Ogledov: 654; Prenosov: 92
.pdf Celotno besedilo (4,24 MB)
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6.
The anchored pile wall optimization using NLP approach
Helena Vrecl-Kojc, 2005, izvirni znanstveni članek

Opis: The type of a retaining structure as well as the structure configuration mainly depends on geological conditions. If geological, urban and other data allow an alternative, the costs should also be considered as an important factor. In geotechnical practise, pile walls are especially used in excavations, in the erection of traffic facilities and in the sanitation of landslides. This paper is aimed at presenting economical differences between cantilever and anchoring pile walls and the impact of different parameters on costs. The optimization method, which uses mathematical programming, gives an optimal solution to geometry, self-manufacturing costs, and other characteristics of the structure in a uniform optimization process. This paper presents the optimization process using the nonlinear programming (NLP) approach for the anchored pile wall. The application presented only serves to confirm the effectiveness of the proposed optimization method. Therefore, the retaining structure is situated in homogeneous non-cohesive soil at three different soil friction angles of 35°, 30° and 25°. The generalized analytical method, the USA method, which was first introduced by Bowles [3], isused in the application. The analysis of the results shows the impact of parameters, the main controlling factors, configuration geometry and savings. The optimal results allowed from 18 up to 47 per cent savings compared to the cantilever pile wall depending on ground and structure input data and the excavation depth.
Ključne besede: civil engineering, optimum design, retaining structures, USA analytical method, nonlinear programming
Objavljeno v DKUM: 16.05.2018; Ogledov: 855; Prenosov: 54
.pdf Celotno besedilo (216,45 KB)
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7.
Agricultural households in mountain areas in pre- and post-accession Slovenia
Štefan Bojnec, Kristina Knific, 2010, pregledni znanstveni članek

Opis: This paper analyses structural changes in agriculture and agricultural households in the mountainous areas of the Gorenjska region in Slovenia. The focus is on agricultural multifunctional roles, agricultural and agricultural households’ structural changes pre- and post-accession of Slovenia to the European Union (EU) on the basis of datasets obtained by two in-depth surveys from 2001 and 2007. The analyses confirm adjustments of farm households to the use of subsidies and new regulations, and diversification of agricultural households’ incomes. Short-term and long-term strategies of farm households vary depending on farms’ natural factor endowments for agriculture, farm size and structures of farm households, availability of agricultural land and their rental values, diversification of incomes with self-employment and employment outside the farm household.
Ključne besede: mountainous areas, agricultural structures, income diversification, household strategies, multifunctional development, Gorenjska, Slovenia, European Union
Objavljeno v DKUM: 29.03.2018; Ogledov: 574; Prenosov: 73
.pdf Celotno besedilo (121,38 KB)
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8.
Financial aspects of a seismic base isolation system for a steel high-rack structure
Vojko Kilar, Simon Petrovčič, Simon Šilih, David Koren, 2013, izvirni znanstveni članek

Opis: The paper deals with the effects and costs of implementing a base isolation system for the mitigation of the seismic risk of an existing steel rack structure. Different realistic distributions of the payload mass and occupancy levels, which form different plan asymmetric variants, have been analysed. The results obtained by the pushover analysis (N2 method) are presented as top floor envelopes and as plastic hinge damage patterns. In the presented cost study, the cost of the implementation of the proposed base isolation system is compared with the estimated costs of structural repairs to the damaged structural members of the superstructure, as well as with estimated expenses of the downtime period. The results have shown that base isolation is, in general, not economically feasible for lower ground motion intensities, whereas it could be of great benefit in the case of moderate and high intensities, especially if the downtime period is taken into account.
Ključne besede: rack structures, seismic behaviour, base isolation, cost efficiency, mass eccentricity, pushover analysis
Objavljeno v DKUM: 07.08.2017; Ogledov: 833; Prenosov: 119
.pdf Celotno besedilo (999,00 KB)
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9.
Fatigue crack initiation and propagation in lotus-type porous material
Srečko Glodež, Sašo Dervarič, Janez Kramberger, Matjaž Šraml, 2016, izvirni znanstveni članek

Opis: The investigation of fatigue strength of lotus-type structure with nodular cast iron as a base material using computational model is analysed in present study. The irregular pores distribution in transversal and longitudinal direction, regarding the external loading, is considered in the computational models. The complete fatigue process of analyzed porous structure is then divided into the crack initiation (Ni) and crack propagation (Np) period where the total fatigue life (N) is defined as: N = Ni + Np. The crack initiation period is determined using strain life approach where elastic-plastic numerical analysis is performed to obtain the total strain amplitude in the critical stress fields around the pores. The simplified universal slope method is then used to determine the number of stress cycles, Ni, required for formation of initial cracks. The number of stress cycles, Np, required for crack propagation from initial to the critical crack length is also numerically determined using finite element (FE) models, in the frame of Abaqus computation FEM code. The maximum tensile stress (MTS) criterion is considered when analyzing the crack path inside the porous structure. The performed computational analyses show that stress concentrations around individual pores are higher when external loading is acting in transversal direction in respect to the pore distribution. Therefore, further computational analyses regarding crack initiation and crack propagation period have been done only for pores distribution in transversal direction.
Ključne besede: lotus-type porous structures, fatigue crack initiation, fatigue crack propagation, numerical analysis
Objavljeno v DKUM: 02.08.2017; Ogledov: 929; Prenosov: 363
.pdf Celotno besedilo (4,75 MB)
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10.
Experimental testing of single APM spheres
Matej Vesenjak, Lovre Krstulović-Opara, 2010, objavljeni znanstveni prispevek na konferenci

Opis: Advanced pore morphology (APM) foam, consisting of sphere-like metallic foam elements, proves to have advantageous mechanical properties and unique application adjustability. Since the APM foam manufacturing procedure has been developed recently, the mechanical characterization of these materials is still very limited. Therefore, the purpose of this research was to determine the behaviour of APM spheres and its composites when subjected to quasi-staticand dynamic compressive loading. The results of the performed research have shown valuable mechanical properties of the composite APM foam structures, offering new possibilities for their use in general engineering applications.
Ključne besede: advanced pore morphology, foam, composite APM foam structures
Objavljeno v DKUM: 26.07.2017; Ogledov: 961; Prenosov: 339
.pdf Celotno besedilo (1,61 MB)
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