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See detailDevelopment of a new design method to define the rotation capacity of steel hollow sections
Saloumi, Elsy ULg

Doctoral thesis (2016)

The present PhD thesis is dedicated to the characterisation of hollow section shapes’ rotational capacity. More precisely, the effort was made towards suggesting new ways to resort to plastic analysis, by ... [more ▼]

The present PhD thesis is dedicated to the characterisation of hollow section shapes’ rotational capacity. More precisely, the effort was made towards suggesting new ways to resort to plastic analysis, by defining a new and accurate proposition to characterise the rotation capacity Rcap of sections, which could be associated with the rotation demand of a structure Rdem. Therefore, the purpose of this thesis is to establish a direct dependence of the rotation capacity Rcap with a newly defined cross-section slenderness CS. Hence, current design standards disregard the rotation demand of the structure and allow plastic analysis based on a plate slenderness limit. To achieve this purpose, an experimental campaign was performed consisting in 23 bending tests on square and rectangular hollow sections tested in bending, in addition to 8 stub columns. Then, a numerical model based on the finite element software FINELg was calibrated to well represent these experimental tests, as well as cold-formed bending tests from literature. Based on these results, a good agreement between experimental and numerical results was shown and the numerical software was therefore validated. Accordingly, since the numerical software was proved to well represent the bending behaviour of hollow beams, around 8000 finite element simulations were performed while varying sections dimensions, material properties and loading configuration. These results reported that actual standards limitations were inappropriate, and stricter values were proposed. Moreover, based on the numerical computations, a continuous curve capable of describing the rotation capacity of sections as a function of the cross-section slenderness was proposed. The production route, loading application and yield strength were identified as key parameters having a major impact on the rotation capacity of sections. Consequently, different curves were proposed for each parameter; based on these curves, the rotation capacity of the section could be compared to the rotation demand of a structure in order to obtain a practical, safe, and reliable design calculation. [less ▲]

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See detailUncertainties in determination of fire resistance by experimental testing and by calculation
Dumont, Fabien ULg; Gernay, Thomas ULg; Franssen, Jean-Marc ULg

Conference (2016, November 24)

In Europe, certification of the fire resistance of building construction elements can be assessed by experimental testing or by calculation. To date, both communities (testing and calculation) express the ... [more ▼]

In Europe, certification of the fire resistance of building construction elements can be assessed by experimental testing or by calculation. To date, both communities (testing and calculation) express the fire resistance results in a deterministic way, i.e. each fire resistance result consists in a single number as if there was no uncertainty. However, when asking different partners within a community to assess the fire resistance of a given element of building construction subjected to a given fire scenario (a so-called “round robin” exercise), the reported results exhibit a very significant variability. Recent efforts have been undertaken to evaluate the extent of the scatter for fire resistance results, i.e. a process of "uncertainty evaluation". This process recognizes the fact that, for a given element of building construction and a given fire scenario, only a probability distribution (as opposite to a deterministic value) can be attributed to the fire resistance result. This approach opens the door to probabilistic reporting as an alternative to deterministic one. [less ▲]

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See detailIntroduction : pour une troisième voie entre hack et yack ?
Dozo, Björn-Olav ULg

Conference (2016, November 24)

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See detailEvaluation du cursus  Sciences industrielles et de l’ingénieur industriel
Courard, Luc ULg

Conference given outside the academic context (2016)

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Peer Reviewed
See detailStatistical study of Saturn's auroral electron properties with Cassini/UVIS FUV spectral images
Gustin, Jacques ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

in Icarus (2016)

About 2000 FUV spectra of different regions of Saturn's aurora, obtained with Cassini/UVIS from December 2007 to October 2014 have been examined. Two methods have been employed to determine the mean ... [more ▼]

About 2000 FUV spectra of different regions of Saturn's aurora, obtained with Cassini/UVIS from December 2007 to October 2014 have been examined. Two methods have been employed to determine the mean energy 〈E〉 of the precipitating electrons. The first is based on the absorption of the auroral emission by hydrocarbons and the second uses the ratio between the brightness of the Lyman-α line and the H2 total UV emission (Lyα/H2), which is directly related to 〈E〉 via a radiative transfer formalism. In addition, two atmospheric models obtained recently from UVIS polar occultations have been employed for the first time. It is found that the atmospheric model related to North observations near 70° latitude provides the results most consistent with constraints previously published. On a global point of view, the two methods provide comparable results, with 〈E〉 mostly in the 7–17 keV range with the hydrocarbon method and 〈E〉 in the 1–11 keV range with the Lyα/H2 method. Since hydrocarbons have been detected on ∼20% of the auroral spectra, the Lyα/H2 technique is more effective to describe the primary auroral electrons, as it is applicable to all spectra and allows an access to the lowest range of energies (≤5 keV), unreachable by the hydrocarbon method. The distribution of 〈E〉 is found fully compatible with independent HST/ACS constraints (emission peak in the 840–1450 km range) and FUSE findings (emission peaking at pressure level ≤0.2 µbar). In addition, 〈E〉 exhibits enhancements in the 3 LT–10 LT sector, consistent with SKR intensity measurements. An energy flux–electron energy diagram built from all the data points strongly suggests that acceleration by field-aligned potentials as described by Knight's theory is a main mechanism responsible for electron precipitation creating the aurora. Assuming a fixed electron temperature of 0.1 keV, a best-fit equatorial electron source population density of 3 × 103 m−3 is derived, which matches very well to the plasma properties observed with Cassini MAG and CAPS/ELS instruments. However, several auroral regions are characterized by relatively high 〈E〉 and low energy flux, suggesting that additional processes such as plasma injections or magnetic reconnections must be accounted for to explain the emission in these regions. The Lyα/H2 ratio technique can be used to build maps of 〈E〉 from single spectral images. As expected, preliminary results show that the spatial distribution of 〈E〉 is not uniform, as seen on Jupiter. Our study reveals that a fraction of the aurora is due to very low energy electrons (<1 keV). Even in this case, comparisons between observed and modeled spectra show that 100 eV is a suitable value to represent the average energy of the secondary electrons. [less ▲]

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See detailPost-fire assessment of concrete structures. Safe for continued use?
Molkens, Tom; Gernay, Thomas ULg; Van Coile, Ruben

Conference (2016, November 24)

After a fire in a building, questions arise regarding the post-fire fire capacity of the structure. Assessment of post-fire capacity of structural elements should consider the residual safety level which ... [more ▼]

After a fire in a building, questions arise regarding the post-fire fire capacity of the structure. Assessment of post-fire capacity of structural elements should consider the residual safety level which, in the absence of codification, requires performing a full probabilistic analysis. Therefore, an easy-to-use method is presented which allows to make a probabilistic calculation, using only analytical formulas and a pre-calculated graph. The method is applied to a real case study, consisting of a fire that took place in an apartment building in Belgium, indicating sufficient load bearing capacity for further use. [less ▲]

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See detailAucun parti n’envisage de limiter les cumuls dans le temps
Grandjean, Geoffrey ULg

Article for general public (2016)

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See detailQu’en est-il des représentations du vieillissement dans notre société ? Quelles conséquences sur la santé de nos aînés ?
Missotten, Pierre ULg; Clesse, Audrey ULg

Conference given outside the academic context (2016)

Depuis des décennies, la vieillesse est abordée en termes médicaux ou de coûts sociétaux. N’est-il pas temps de tordre le cou aux idées reçues ? Même si la société évolue, nos perceptions du ... [more ▼]

Depuis des décennies, la vieillesse est abordée en termes médicaux ou de coûts sociétaux. N’est-il pas temps de tordre le cou aux idées reçues ? Même si la société évolue, nos perceptions du vieillissement sont encore trop souvent associées à la tristesse, la solitude, la maladie, l’exclusion ou l’angoisse. Autant de stéréotypes qui renforcent une image dégradée de la vieillesse et qui nécessite un changement de regard. Plusieurs études démontrent que nos seniors déclarent bien vivre, se sentent en bonne santé physique et psychologique, se jugent entourés et estiment que la vie leur procure du plaisir... Vieillir c'est accumuler des connaissances et développer de l'expertise, c'est vivre en se centrant davantage sur les informations positives au détriment des négatives. Cette conférence aura donc pour objectif d'amener à une vision plus réaliste (et donc moins pessimiste!) du vieillissement. Et l'enjeu est de taille: que nous soyons jeunes ou moins jeunes, notre vision du vieillissement a un impact important sur la santé physique et mentale des aînés! Si cette thématique vous interpelle ... [less ▲]

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See detailDevelopment of a new design method for steel hollow section members resistance
Hayeck, Marielle ULg

Doctoral thesis (2016)

This dissertation presents research done in the field of enhancing the performance and the carrying capacity of tubular members, through the development of an original design approach based on the ... [more ▼]

This dissertation presents research done in the field of enhancing the performance and the carrying capacity of tubular members, through the development of an original design approach based on the “Overall Interaction Concept” (O.I.C.). The proposed approach makes use of the interaction between the two ideal behaviours of structural members (resistance and instability) and includes the influence of initial imperfections (out-of straightness, residual stresses, non-homogenous material), to calculate the resistance of a structure through a single parameter: “relative slenderness”. A test program was carried out as a part of a European project named ‘HOLLOPOC’ to determine the experimental behaviour of beam-columns loaded by bi-axial bending with axial force. Twelve buckling tests, consisting of hot-rolled and cold-formed rectangular and circular hollow section members were conducted. These tests were accompanied by preliminary measurements of cross-section geometry, material properties, geometrical imperfections, residual stresses as well as stub column tests. Besides, a finite element model was calibrated on the basis of these tests. For both the present test series and another one from the literature, it was shown that the FE models were capable of replicating accurately the response and resistance of the experiments. Accordingly, the validated FE models have been further used in extensive numerical studies, and a database comprising more than seventy thousand results was built consecutively. Based on these computations, design proposals were made, by considering identified governing parameters, within the context of the Overall Interaction Concept, using an extension of the Ayrton-Perry approach. Finally, a safely evaluation was completed to check the proposed formulae against the results of current Eurocode 3 rules. [less ▲]

Detailed reference viewed: 24 (3 ULg)
See detailNaissance et prime jeunesse de l’Université de Liège, 1816-1835
Lanneau, Catherine ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 17 (0 ULg)
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Peer Reviewed
See detailSustainability and management control. Exploring and theorizing control patterns in large European firms
Crutzen, Nathalie ULg; Zvezdov, Dimitar; Schaltegger, Stefan

in Journal of Cleaner Production (2016), Online version

Detailed reference viewed: 18 (1 ULg)
See detail“Toute l'âme résumée” de Mallarmé : un art poétique déjoué
Durand, Pascal ULg

Scientific conference (2016, November 23)

Detailed reference viewed: 21 (1 ULg)
See detailDes concepts en classe d'histoire : pourquoi et comment ?
Jadoulle, Jean-Louis ULg

Scientific conference (2016, November 23)

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See detailLaser Additive Manufacturing of Metal Matrix Composites
Mertens, Anne ULg

Learning material (2016)

Current trends in the mechanics and energy industries impose increasing demands on metallic materials, combining elevated service temperatures and severe mechanical solicitations. Metal matrix composite ... [more ▼]

Current trends in the mechanics and energy industries impose increasing demands on metallic materials, combining elevated service temperatures and severe mechanical solicitations. Metal matrix composite coatings with ceramic reinforcements are good candidates in view of fulfilling the requirements for an improved mechanical durability, and for other complex functions (e.g. self-lubrication, biocompatibility...). First of all, this paper provides an introduction to metal matrix composites with a particular attention for the process known as laser cladding that appears as a promising technology for making composite coatings. In this process, a (mixture of) metallic powder(s) is projected onto a substrate through a nozzle and simultaneously melted by a laser beam. Laser cladding is characterised by ultra-fast solidification and cooling rates, thus giving rise to ultra-fine microstructures and potentially enhanced mechanical properties. The paper thus focuses on the relationships between the thermal history during the production of a composite coating, and the resulting microstructure and properties, with special attention to the dissolution of ceramic particles (e.g. carbides) and to interfacial reactions taking place between the particles and the metallic matrix. [less ▲]

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See detailNon muro ma porta. Forza e fragilità al femminile nell'arte di Anna Mainardi
Bugini, Mariaelena ULg

Scientific conference (2016, November 23)

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See detailCOP22: What's next?
Ozer, Pierre ULg

Scientific conference (2016, November 23)

Detailed reference viewed: 59 (2 ULg)
See detailConjonctivo Mullerectomy in Eyelid Ptosis Surgery
XHAUFLAIRE, Gaël ULg

Conference (2016, November 23)

Conjonctivo-mullerectomy : codified surgical technique for eyelid ptosis repair. Indications, unusual indications, contraindications, limits, risks. Technique description. Video presentation.

Detailed reference viewed: 14 (2 ULg)