References of "Rossi, Barbara"
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See detailCarrying capacity of stainless steel columns in the low slenderness range.
Rossi, Barbara ULg; Rasmussen, Kim J.R.

in Journal of Structural Engineering (in press)

The strength of thin-walled stainless steel columns has been investigated extensively over the past few years. In European standards, the concept of section classification for determining the cross ... [more ▼]

The strength of thin-walled stainless steel columns has been investigated extensively over the past few years. In European standards, the concept of section classification for determining the cross-section capacity is used. In this system, for Class 4 cross-sections, the Effective Width Method (EWM) must be used to account for the effect of local buckling. Because of the complexity and limitations of this method, other methods have been developed, such as the Direct Strength Method (DSM) for cold-formed thin-walled profiles and the Continuous Strength Method (CSM), initially established for members made of nonlinear metallic materials. In the CSM, to take advantage of strain hardening, a deformation-based design approach employing a continuous relationship between the cross-sectional slenderness and the cross-sectional deformation capacity is used. To a large extent, the CSM yield accurate predictions, especially in the low slenderness range where the current DSM design procedures for members submitted to pure compression tends to produce conservative predictions, for materials with pronounced strain hardening such as stainless steel alloys. The present paper presents an extension of the traditional DSM which provides accurate design strength predictions in the low slenderness range for stainless steel thin-walled section columns failing by distortional, local and overall buckling. It contains practical information concerning the reference experimental data and draws conclusions about the justification of the proposed analytical formula. The paper is divided into three main parts: the description of the database, the establishment of the design model and a reliability analysis of the method. [less ▲]

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See detailNumerical simulation of the Roll forming of thin-walled sections and evaluation of corner strength enhancement
Rossi, Barbara ULg; Degée, Hervé ULg; Boman, Romain ULg

in Finite Elements in Analysis & Design (2013), 72

Cold roll forming modifies the mechanical properties of thin-walled profiles by strain hardening. The understanding of this phenomenon, which is rather good for profiles made of traditional construction ... [more ▼]

Cold roll forming modifies the mechanical properties of thin-walled profiles by strain hardening. The understanding of this phenomenon, which is rather good for profiles made of traditional construction steel, is mandatory for assessing the member resistance. Less information is however available for profiles made of materials exhibiting a pronounced degree of nonlinearity of the stress-strain curve such as high-strength and stainless steels. Current codes generally encounter difficulties for modelling this fabrication process because of the size of industrial mills. Indeed, accurate modelling of the continuous cold roll forming process using finite elements requires a huge number of elements leading to excessive CPU times. Therefore, modellers usually reduce the geometry of the formed sheet or increase the size of the finite elements, inducing a loss of accuracy in the results. In this work, the finite element software METAFOR is used to model cold roll forming of channel profiles made of high-strength and stainless steels. The numerical results, expressed in terms of corner strength enhancement versus radius–to–thickness ratio, are compared against an existing predictive model. [less ▲]

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See detailStrength enhancements in cold-formed structural sections — Part I: Material testing
Afshan, Sheida; Rossi, Barbara ULg; Gardner, Leroy

in Journal of Constructional Steel Research (2013), 83

This paper describes a material test programme carried out as part of an extensive study into the prediction of strength enhancements in cold-formed structural sections. The experiments cover a wide range ... [more ▼]

This paper describes a material test programme carried out as part of an extensive study into the prediction of strength enhancements in cold-formed structural sections. The experiments cover a wide range of cross-section geometries – twelve Square Hollow Sections (SHS), five Rectangular Hollow Sections (RHS) and one Circular Hollow Section (CHS), and materials – austenitic (EN 1.4301, 1.4571 and 1.4404), ferritic (EN 1.4509 and 1.4003), duplex (EN 1.4462) and lean duplex (EN 1.4162) stainless steel and grade S355J2H carbon steel. The experimental techniques implemented, the generated data and the analysis methods employed are fully described. The results from the current test programme were combined with existing measured stress-strain data on cold-formed sections from the literature and following a consistent analysis of the combined data set, revised values for Young’s modulus E and the Ramberg-Osgood material model parameters n, n' 0.2,u and n'0.2,1.0 are recommended. A comparison between the recommended values and the codified values provided in AS/NZS 4673, SEI/ASCE-8 and EN 1993-1-4 is also presented. The test results are also used in a companion paper for developing suitable predictive models to determine the strength enhancements in cold-formed structural sections that arise during the manufacturing processes. [less ▲]

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See detailStrength enhancements in cold-formed structural sections — Part II: 2 Predictive models
Rossi, Barbara ULg; Afshan, Sheida; Gardner, Leroy

in Journal of Constructional Steel Research (2013), 83

Cold-formed structural sections are manufactured at ambient temperature and hence undergo plastic deformations, which result in an increase in yield stress and a reduction in ductility. This paper begins ... [more ▼]

Cold-formed structural sections are manufactured at ambient temperature and hence undergo plastic deformations, which result in an increase in yield stress and a reduction in ductility. This paper begins with a comparative study of existing models to predict this strength increase. Modifications to the existing models are then made, and an improved model is presented and statistically verified. Tensile coupon data from existing testing programs have been gathered to supplement those generated in the companion paper and used to assess the predictive models. A series of structural section types, both cold-rolled and press-braked, and a range of structural materials, including various grades of stainless steel and carbon steel, have been considered. The proposed model is shown to offer improved mean predictions of measured strength enhancements over existing approaches, is simple to use in structural calculations and is applicable to any metallic structural sections. It is envisaged that the proposed model will be incorporated in future revisions of Eurocode 3. [less ▲]

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See detailGeneralized multistage mechanical model for nonlinear metallic materials
Hradil, Petr; Talja, Asko; Real, Esther et al

in Thin-Walled Structures (2013), 63

Metallic alloys have a significant role in thin-walled engineering structures due to their unique properties such as corrosion resistance, low density or durability. Their mechanical behaviour is usually ... [more ▼]

Metallic alloys have a significant role in thin-walled engineering structures due to their unique properties such as corrosion resistance, low density or durability. Their mechanical behaviour is usually nonlinear, and this nonlinearity can be further increased during the work-hardening process. In such cases, designers have to take the proper stress-strain relationship into account to obtain reliable prediction of deformations or internal forces. In this paper, a theoretical model is proposed to match different kinds of measured data or already existing stress-strain models. It is flexible to accommodate any number of measured or recommended material parameters, and therefore makes design rules independent on testing standards. It is particularly suitable for computer code implementation. The approximate inversion of the multistage model is also included in the presented study. The general formula is applied on the set of parameters typically available for structural stainless steels in Europe (0.2% and 1.0% proof strength and ultimate strength) and compared to the existing models by curve-fitting of analytical equations to measured stresses and strains of austenitic, duplex and ferritic stainless steels. The comparisons clearly showed that this three-stage application of the generalized multistage model yields more accurate results compared to the existing material models both in direct and inverse form. [less ▲]

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See detailExtension of the DSM to welded H profile cross-sections
Rossi, Barbara ULg; Li, Yongzhen ULg

in Research and Applications in Structural Engineering, Mechanics and Computation (2013)

The objective of the paper is to assess the accuracy of current Direct Strength Method (DSM) equations applied to steel structural welded H shapes in axial compression. Commercialised hot-rolled H ... [more ▼]

The objective of the paper is to assess the accuracy of current Direct Strength Method (DSM) equations applied to steel structural welded H shapes in axial compression. Commercialised hot-rolled H sections covering IPE, HE, HD, HL, HP, W and UB profiles and made of three grades (235MPa, 355MPa and 460MPa) were treated in (Li & Rossi 2012). This analysis focuses on welded sections made of the same three grades, including sections characterized by local buckling with a significant post-buckling reserve. The finite element model is described. Then, the results of a parametric analysis using the finite element model are re-ported. The codified resistances are also compared to the numerical results. For each cross-section, the recently developed analytical expressions provided in (Seif & Schafer 2010) for hot-rolled profiles are used to cal-culate the elastic cross-section local buckling stress. A comparison with CUFSM results is also reported. Then, the possibility to use the concept of DSM for the design of structural welded steel shapes is discussed. [less ▲]

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See detailStainless steel in structures in view of sustainability
Rossi, Barbara ULg

Conference (2012, December)

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See detailCarrying capacity of stainless steel columns in the low slenderness range
Rossi, Barbara ULg; Rasmussen, Kim J.R.

in 6th International Conference on Coupled Instabilities in Metal Structures : CIMS, Glasgow 3-5 December 2102 (2012, December)

In European standards, for Class 4 cross-sections, the Effective Width Method (EWM) must be used to account for the effect of local buckling. Because of the complexity of this method, other methods have ... [more ▼]

In European standards, for Class 4 cross-sections, the Effective Width Method (EWM) must be used to account for the effect of local buckling. Because of the complexity of this method, other methods have been developed, such as the Direct Strength Method (DSM) for cold-formed thin-walled profiles and the Continuous Strength Method (CSM), initially established for members made of stainless steels. To a large extent, the CSM yield accurate predictions, especially in the low slenderness range where the current DSM design procedure tends to produce conservative results, for materials with pronounced strain hardening. The present paper presents an extension of the DSM which provides accurate strength predictions in the low slenderness range for stainless steel thin-walled section columns failing by distortional, local and overall buckling. [less ▲]

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See detailFinite element model for the extension of the direct strength method to hot-rolled profile cross-sections
Li, Yongzhen ULg; Rossi, Barbara ULg

in Proceedings of the 12th Nordic Steel Construction Conference (2012, September 05)

Abstract: In the present research, a geometrically and materially nonlinear analysis using the FE method has been conducted to evaluate the resistance of axially compressed hot-rolled H profile cross ... [more ▼]

Abstract: In the present research, a geometrically and materially nonlinear analysis using the FE method has been conducted to evaluate the resistance of axially compressed hot-rolled H profile cross-sections. The FE model was firstly duly verified against experimental data and then used to carry a parametric analysis. The goal of the analysis is to propose a new Direct Strength Method (DSM) strength curve intended for calculating the resistance of non-compact and slender hot-rolled H profile cross-sections. [less ▲]

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See detailProceedings of the 12th Nordic Steel Construction Conference
Li, Yongzhen; Rossi, Barbara ULg

Conference (2012, September)

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See detailPredictive models for strength enhancements in cold-formed structural sections
Rossi, Barbara ULg; Afshan, Sheida; Gardner, Leroy

Conference (2012, September)

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See detailRobustness of steel and composite buildings suffering the dynamic loss of a column
Coméliau, Ludivine ULg; Rossi, Barbara ULg; Demonceau, Jean-François ULg

in Structural Engineering International (2012), 22(3), 323-329

In case a vehicle impacts a building frame, one or several columns may be damaged or even completely destroyed. Nowadays, it is a concern to mitigate the risk of progressive collapse of the whole ... [more ▼]

In case a vehicle impacts a building frame, one or several columns may be damaged or even completely destroyed. Nowadays, it is a concern to mitigate the risk of progressive collapse of the whole structure further to such a localised exceptional event. Although this robustness requirement is part of several design codes, very few precise practical guidelines are provided, especially as far as dynamic failures are concerned. The present research focuses on building frames suffering the loss of one internal column. The dynamic response is more specifically investigated, with the aim to understand this behaviour in order to eventually derive simplified procedures for robustness assessment. This paper first briefly presents the main previous achievements related to the prediction of the static response of a plane frame suffering a column loss. The investigations into the dynamic behaviour are then summarised, which constitutes the core topic of the paper. For sake of simplicity, the dynamic response is described using a basic substructure that was proved to show many similarities in behaviour with a global frame losing a column. A simplified model is finally developed for the prediction of the considered system dynamic response. [less ▲]

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See detailPrediction of the cross-section capacity of hot-rolled profiles using the direct strength method and the continuous strength method
Li, Yongzhen ULg; Rossi, Barbara ULg

in Chan, S.L.; Shu, G.P. (Eds.) Proceedings of seventh International Conference on Advances in Steel Structures (2012, April)

Material yielding on one hand and local buckling on the other hand limit the cross-section capacity of steel structural members. Current structural design codes use the concept of cross-section ... [more ▼]

Material yielding on one hand and local buckling on the other hand limit the cross-section capacity of steel structural members. Current structural design codes use the concept of cross-section classification to determine the cross-section resistance of hot-rolled profiles. In this system, the Effective Width Method (EWM) is employed to account for local buckling effects for slender, class 4, cross-sections. Alternative design methods for treatment of local buckling in metallic cross-sections have been proposed, including the Direct Strength Method (DSM), developed for cold-formed steel structural profiles, and, recently, the Continuous Strength Method (CSM). The DSM is based on the assumption that the strength can be predicted from the ratio of the yield strength to the elastic critical load in conjunction with a strength curve for the entire cross-section. Thus it is essentially an extension of the use of column curves for global buckling, but with application to local buckling instability. The CSM is a deformation-based design approach which is based on a continuous relationship between cross-sectional slenderness and cross-section deformation capacity and a rational exploitation of strain hardening. This paper is focused on the evaluation of the cross-sectional resistance of hot-rolled structural profiles. Test data from literature experimental programmes have been gathered and analysed to compare the predictions from the DSM and CSM design approaches. [less ▲]

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See detailLife-cycle assessment of residential buildings in three different European locations, case study
Rossi, Barbara ULg; Marique, Anne-Françoise ULg; Reiter, Sigrid ULg

in Building & Environment (2012), 51

The paper presents the comparative results of the life-cycle assessment (LCA) of one residential building with two constructive systems in Brussels and one steel frame house located in three different ... [more ▼]

The paper presents the comparative results of the life-cycle assessment (LCA) of one residential building with two constructive systems in Brussels and one steel frame house located in three different European towns: Brussels (Belgium), Coimbra (Portugal) and Luleå (Sweden). In a recent study, a modular building was studied in Coimbra and Luleå. It was shown that in terms of CO2 emissions, the Use Stage was the most harmful stage during the building life-cycle for Coimbra climate. Contrarily, in Luleå, it was the Product Stage, despite energy consumption being higher than Coimbra, due to the way electricity and heat are generated. In the present study, two structural systems are first compared for the Belgian house: steel frame and traditional masonry. A different life-cycle scenario is taken into account for the steel frame house for the three different locations, in which the monthly temperatures, energy mix, heating and cooling systems are defined. The LCA is carried out using the basic tool described in the companion paper. It is worth recalling that the results obtained with the basic tool were verified against Pleiades+Comfie and Equer software, enabling to carry out a complete LCA, for Brussels. Our results confirm that for all the three climates, the Use Stage (Operational energy) is the most harmful period during the building life-cycle and that the energy mix of the country strongly influences the equivalent CO2 emissions related to the Use Stage (Operational carbon) and may entirely reverse the conclusions about the life-cycle carbon footprint of the building. [less ▲]

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See detailLife-cycle assessment of residential buildings in three different European locations, basic tool
Rossi, Barbara ULg; Marique, Anne-Françoise ULg; Glaumann, Mauritz et al

in Building & Environment (2012), 51

The paper deals with the development of a tool used for the life cycle assessment of residential buildings located in three different European towns: Brussels (Belgium), Coimbra (Portugal) and Luleå ... [more ▼]

The paper deals with the development of a tool used for the life cycle assessment of residential buildings located in three different European towns: Brussels (Belgium), Coimbra (Portugal) and Luleå (Sweden). The basic tool focuses on the structure and the materials of the buildings and permits the evaluation of the Embodied energy, Embodied carbon and yearly energy consumption. For that purpose, a different set of original data is taken into account for each location, in which the monthly temperatures, energy mix, heating and cooling systems are defined. The energy consumption, being for heating space or water, for cooling or for lighting is transformed into CO2 emissions to deduce the Operational carbon as well. The influence of the energy mix can therefore be assessed in the basic tool. As a matter of fact, the heating and cooling systems habitually used in the three countries are also of great importance. The District Heating system, is, for instance, incorporated in the basic tool. The presence of solar water heater or photovoltaic panels is also strongly influencing the operational carbon. After a short literature review on building LCA and the description of the basic tool, the software Pleiades+Comfie combined with Equer is used to achieve the complete LCA for one building using two different load bearing frames. The results of the calculations for Brussels climate are verified against these software results. The dependence of the results to parameters such as climate, energy mix and habits is then discussed in the companion paper. [less ▲]

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See detailPredictive models for strength enhancements in cold-formed structural sections
Rossi, Barbara ULg; Afshan, Sheida; Gardner, Leroy

in 14th International Symposium on Tubular Structures: ISTS14, London 12-14 September 2012 (2012)

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See detailStainless steel in structures in view of sustainability
Rossi, Barbara ULg

in Stainless steel in structures: Fourth International Structural Stainless Steel Experts Seminar: Ascot 6)7 December 2012 (2012)

Recent years have seen an increase in the use of structural stainless steel, mainly owing to its aesthetic and architectural qualities alongside durability. Among stainless steels, ferritic grades are ... [more ▼]

Recent years have seen an increase in the use of structural stainless steel, mainly owing to its aesthetic and architectural qualities alongside durability. Among stainless steels, ferritic grades are characterized by low nickel content resulting in a more cost-stable and economic material compared with austenitic stainless steels, allowing a balanced approach between economic and environmental aspects. As an introduction, this paper presents the recent research outcomes especially concerning the currently ongoing RFCS project “Structural Applications of Ferritic Stainless Steels”. Then, attention is paid to the advantages and challenges associated with the use of this material in recent construction projects in view of sustainability. Life cycle analysis is explained. The background of the new European standard EN 15804 is described, including Module D, which takes now into account the end-of-life phase. Life cycle inventories of stainless steel products (cold-rolled coils and quarto plate) are presented. Depending on the fraction of material recovered at the end of the lifespan, several potential impacts such as the Primary Energy Demand and Global Warming Potential are compared for four grades: 1.4301 (AISI 304) and 1.4401 (AISI 316) austenitic grades, 1.4016 (AISI 430) ferritic grade and 1.4462 (AISI 2205) duplex grade. The influence of the end-of-life credits and loads is underlined. [less ▲]

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See detailRecent research into thin-walled ferritic stainless steel profiles
Rossi, Barbara ULg; Cashell, Katherine A.

in 6th International Symposium on Steel Structures: ISSS 2011, Seoul, 3-5 November 2011 (2011, November)

Although stainless steel offers a wide variety of interesting and valuable properties such as fire resistance and durability, it has not been commonly used in structural applications. This is changing ... [more ▼]

Although stainless steel offers a wide variety of interesting and valuable properties such as fire resistance and durability, it has not been commonly used in structural applications. This is changing however as recent years have seen an increase in the use of structural stainless steel, mainly owing to its aesthetic and architectural qualities. A number of similarities exist between stainless steel and typical carbon steel but there are sufficient differences to necessitate specific treatment in design standards for stainless steel, focused on structural applications. Austenitic stainless steels have been broadly studied in recent years but less information is available regarding the ferritic grades. This is despite the fact that ferritic grades have low nickel content resulting in a more cost-stable and economic material compared with austenitic stainless steel. Nevertheless, recent projects have highlighted some of the main features of ferritics. This paper summarizes the outcomes of several studies carried out at the University of Liège on cold-formed stainless steel profiles and also research currently underway at The Steel Construction Institute on ferritic stainless steels. Firstly, the material behavior of Grade 1.4003 is explained. A new method of evaluating the actual mechanical properties in the walls of cold-formed sections is proposed, which is not restricted to a single alloy or type of cross-section. The formulation is established and validated against experimental results. It is also compared to predictive models from various other authors. Secondly, experiments on cold-formed stainless steel lipped channel section columns are described. The profiles failed by combined distortional and overall flexural-torsional buckling. These tests were used to calibrate finite element models and, once verified against the test results, these models were used to generate additional results when necessary. Current design standards were then used to calculate the strength and the results were compared to the tests. On the basis of the conclusions drawn from these analyses, a new Direct Strength Method which takes account of this failure mode has been proposed. Finally, a state-of-the-art discussion is provided based upon the findings of the ongoing RFCS project “Structural Applications of Ferritic Stainless Steel”. In addition, future fire testing of stainless steel columns will be presented. [less ▲]

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