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Nseir Joanna

Professeure HES associée

Hauptkompetenzen

Réemploi des structures en acier

Hauptvertrag

Professeure HES associée

Büro: HEIA_D40.13

Haute école d'ingénierie et d'architecture de Fribourg
Boulevard de Pérolles 80, 1700 Fribourg, CH

BSc HES-SO en Génie civil - Haute école d'ingénierie et d'architecture de Fribourg

MSc HES-SO en Engineering - HES-SO Master

StrMétal - Constructions en acier

Laufend

Evaluation du réemploi de structures légères

AGP

Rolle: Hauptgesuchsteller/in

Financement: SLL-PR

Description du projet : Le présent projet propose une étude et analyse structurale du potentiel de réemploi de structures historiques légères. Ce projet traite les aspects de calcul des structures et d'analyse de leur cycle de vie pour atteindre les objectifs de durabilité, tout en respectant les exigences des normes actuelles. Il est question de profiter de cette richesse structurale historique et d'élaborer une démarche générale et systématique applicable à d'autres structures.

Forschungsteam innerhalb von HES-SO: Serreri Olivier , Nseir Joanna , Redaelli Dario , Grandjean Nicolas , Colomer Pierre , Jusselme Thomas , Hertling Nicolas , Chira Alexandru , Schulthess Lucile

Partenaires académiques: FR - EIA - Institut iTEC

Durée du projet: 01.09.2023 - 31.12.2025

Montant global du projet: 155'000 CHF

Statut: Laufend

2021

Topology optimization of load-bearing capacity

Wissenschaftlicher Artikel

Leyla Mourad, Jeremy Bleyer, Romain Mesnil, Nseir Joanna, Sab Karam, Raphael Wassim

Structural and Multidisciplinary Optimization, 2021 , pp. 1367-1383

Zusammenfassung:

The present work addresses the problem of maximizing a structure load-bearing capacity subject to given material strengthproperties and a material volume constraint. This problem can be viewed as an extension to limit analysis problemswhich consist in finding the maximum load capacity for a fixed geometry. We show that it is also closely linked to theproblem of minimizing the total volume under the constraint of carrying a fixed loading. Formulating these topologyoptimization problems using a continuous field representing a fictitious material density yields convex optimizationproblems which can be solved efficiently using state-of-the-art solvers used for limit analysis problems. We further analyzethese problems by discussing the choice of the material strength criterion, especially when considering materials withasymmetric tensile/compressive strengths. In particular, we advocate the use of a L1-Rankine criterion which tends topromote uniaxial stress fields as in truss-like structures. We show that the considered problem is equivalent to a constrainedMichell truss problem. Finally, following the idea of the SIMP method, the obtained continuous topology is post-processedby an iterative procedure penalizing intermediate densities. Benchmark examples are first considered to illustrate the methodoverall efficiency while final examples focus more particularly on no-tension materials, illustrating how the method is ableto reproduce known structural patterns of masonry-like structures. This paper is accompanied by a Python package based onthe FEniCS finite-element software library
(PDF) Topology optimization of load-bearing capacity. Available from: https://www.researchgate.net/publication/352735567_Topology_optimization_of_load-bearing_capacity

2020

Slenderness-based design criteria to allow for the plastic analysis of tubular beams

Wissenschaftlicher Artikel

Elsy Saloumi, Nseir Joanna, Nicolas Boissonnade

Journal of Constructional Steel Research, 2020

Structural behavior of prestressed ultra-high performance fibre-reinforced concrete beams with and without openings: comparison between experimental results and finite element modelling techniques

Wissenschaftlicher Artikel

Redaelli Dario, Nseir Joanna

American Concrete Institute, ACI, 2020 , pp. 474-483

2019

The role of local buckling in the determination of H.S.S. Rotational capacity

Wissenschaftlicher Artikel

Nseir Joanna

Structural Stability Research Council Annual Stability Conference 2019, SSRC 2019, 2019, 2, pp. 734–755, 2019

2018

Experimental characterization of steel tubular beam-columns resistance by means of the Overall Interaction Concept

Wissenschaftlicher Artikel

Hayeck Marielle, Elsy Saloumi, Nseir Joanna, Nicolas Boissonnade

Thin-walled Structures, 2018 , pp. 92-107

Experimental characterization of steel tubular beam-columns resistance by means of the Overall Interaction Concept

Wissenschaftlicher Artikel

Nseir Joanna,

Thin-Walled StructuresThis link is disabled., 2018, 128, pp. 92–107, 2018

2017

Experimental and numerical characterization of H.S.S. rotational capacity

Wissenschaftlicher Artikel

Elsy Saloumi, Marielle Hayeck, Nseir Joanna, Nicolas Boissonnade

Proceedings of the Annual Stability Conference Structural Stability Research Council 2017, 2017, 2017

Stability and resistance of hollow section steel beam-columns

Wissenschaftlicher Artikel

Elsy Saloumi, Nicolas Boissonnade, Nseir Joanna, Marielle Hayeck

Proceedings of the Annual Stability Conference Structural Stability Research Council 2017, 2017, 2017

An Overall Interaction Concept for an alternative approach to steel members design

Wissenschaftlicher Artikel

Nicolas Boissonnade, Marielle Hayeck, Elsy Saloumi, Nseir Joanna

Journal of Constructional Steel ResearchThis link is disabled., 2017, 135, pp. 199–212, 2017

2016

Influence of imperfections on the local buckling response of hollow structural shapes

Wissenschaftlicher Artikel

Nseir Joanna, Marielle Hayeck, Elsy Saloumi, Nicolas Boissonnade

Structural Stability Research Council Annual Stability Conference 2016, SSRC 2016, 2016, pp. 535–553, 2016

2015

Practical design of hollow structural shapes by means of the overall interaction concept

Wissenschaftlicher Artikel

Nseir Joanna, Marielle Hayeck, Elsy Saloumi, Nicolas Boissonnade

Structural Stability Research Council Annual Stability Conference 2015, SSRC 2015, 2015, pp. 589–610, 2015

2025

Numerical investigation of a wedge-sleeve connection for demountable steel structure

Konferenz ArODES

Joanna Nseir, Elias Abi Haydar, Alexandru Chira

ICCEA 2025 - 8th International Conference on Civil Engineering and Architecture

Link zur Konferenz

Zusammenfassung:

This study investigates the structural performance of a novel modular sleeve connection equipped with a wedge locking mechanism, developed to enhance the reusability of steel structures within a circular construction framework. Nonlinear finite element analyses were carried out in Abaqus to examine the baseline configuration, where the beam and column are joined through a prefabricated welded sleeve–wedge assembly. Two variants were evaluated: a reference model without stiffeners and a modified model reinforced with transverse stiffener plates. The results show that stress concentrations in the unstiffened model are primarily located at the sleeve corners, leading to localized yielding under increasing loads. The inclusion of stiffeners helps redistribute stresses and delays plastic strain development, though yielding remains confined within the joint. Practical considerations highlight limitations of the welded one-piece assembly, particularly with respect to fabrication tolerances and on-site adjustability. Despite these drawbacks, the findings demonstrate the potential of wedge-based sleeve connections for demountable steel structures and establish a foundation for further developments involving bolted, more modular configurations.

Numerical assessment of a modular steel sleeve connection with wedge locking mechanism for demountable structures

Konferenz ArODES

Joanna Nseir, Elias Abi Haydar, Alexandru Chira

Proceedings of International Structural Engineering and Construction

Link zur Konferenz

Zusammenfassung:

This paper presents the numerical assessment of a modular steel sleeve connection incorporating a wedge locking mechanism, developed to enhance reusability and sustainability in steel construction. The connection eliminates welding and drilling of the main members, enabling full disassembly and reuse. An adapted configuration was investigated for central column applications, where multiple beams frame into a single square hollow section column through a four-sided sleeve. Finite element models were developed in Abaqus to evaluate the structural response, focusing on stress redistribution, plastic strain development, and moment–rotation behavior. The results indicate that yielding shifts away from the column face toward the sleeve–beam interface, promoting hinge formation in the beam rather than in the joint core. The connection demonstrates semi-rigid behavior consistent with Eurocode classifications, with stiffness comparable to conventional bolted joints. Overall, the study highlights the potential of modular sleeve connections with wedge locking mechanisms as reliable, demountable alternatives to traditional welded or bolted joints, supporting circular economy strategies in steel construction.

Analysis of the behavior of the Veveyse bridge under impact of massive rockslides :

Konferenz ArODES

a practical case study

Sahar Ismail, Joanna Nseir, Fouad Kaddah

SDSS 2025 : The International Colloqium on Stability and Ductility of Steel Structures

Link zur Konferenz

Zusammenfassung:

On February 2, 2024, a landslide of several hundred cubic meters caused several massive rocks (50 to 100 m3) to fall down the slope of Vevey valley region in Switzerland. The rockslide hit and damaged part of the structure of the A9 Lausanne-Saint-Maurice national road/bridge before settling at the bottom of the slope near the bridge foundation. Luckily, the rockslide did not cause any casualties, nor did it affect any homes. Noting that the structure “Pont de Veveyse” consisting of 2 parallel and identical composite steel and prestressed concrete bridges that was put into service in 1969 ensures the passage of approximately 61000 vehicles/ day. In the bridge region, the geological conditions are very complicated and are characterized by an extended sliding zone that experiences slippage of a few cm per year. Since in this region, erosion and thus, slope as well as rockslides occur naturally and often, the following study was performed to determine the behavior of the bridge under different rockslide impacts. Following the accident, field investigations were conducted to gather information and identify the trajectory of the rockslides and bridge damage. Then, based on the principle of linear impulse and momentum as well as the conservation of linear impulse and momentum, the velocity of rockslides as well as the average impulse forces were calculated. The obtained results were used in the numerical simulations performed using the non-linear software Abaqus to investigate the bridge behavior and responses caused by the impact of the massive rockslide. The effects of impact load, its direction and location on the behavior of the bridge were examined. The obtained results showed that the simulated damage mechanisms agree with field observations. Moreover, bridge stability is affected by the rockslide impacts. The obtained results can be considered a mean to assess the stability of the bridge and perform as guidelines for authorities to mitigate future hazard rockslides impact strategies for the A9 bridge.

Assessment of reuse and retrofit potential for a cold-formed steel structure :

Konferenz ArODES

a case study from Fribourg

Pierre Colomer, Joanna Nseir, Lucile Schulthess, Thomas Jusselme, Nicolas Grandjean, Alexandru Chira

SDSS 2025 : The International Colloqium on Stability and Ductility of Steel Structures

Link zur Konferenz

Zusammenfassung:

This study investigates the potential reuse and retrofit of a cold-formed steel structure originally designed as an industrial plant in Fribourg, Switzerland, during the 1950s and disassembled in 2022. The research aims to assess the feasibility of repurposing the structure, with or without modifications, across various locations in Switzerland, considering different loading conditions. A comprehensive 3D structural analysis was conducted to evaluate the structure's current state under loading conditions prescribed by SIA standards and codes. This analysis identified locations where direct reuse would be possible and areas requiring retrofitting for safe implementation. Multiple retrofitting strategies were proposed to expand the structure's potential deployment range. These modifications aimed to enhance the structure's load-bearing capacity and adaptability to diverse environmental conditions. In parallel, traditional steel solutions were developed as alternatives. A comparative Life Cycle Assessment (LCA) was performed, providing insights into the environmental impacts and sustainability of each option. The study offers guidance for decision-makers, supporting sustainable practices and circular economy principles in construction.

Advanced nonlinear analysis of a retrofitted cold-formed steel portal frame :

Konferenz ArODES

a comparison of traditional and detailed modeling approaches

Alexandru Chira, Joanna Nseir

SDSS 2025 : The International Colloqium on Stability and Ductility of Steel Structures

Link zur Konferenz

Zusammenfassung:

This study presents an in-depth investigation of a cold-formed steel portal frame structure, originally designed in the 1950s, through advanced nonlinear analysis. The research aims to compare traditional structural modelling approaches with more detailed nonlinear modelling techniques while evaluating various retrofitting strategies. A comprehensive nonlinear analysis was conducted, accounting for all sources of nonlinearity. Multiple modelling versions were explored, including beam elements with rigid and pinned connections, as well as a hybrid model incorporating 3D columns modelled with shell or solid elements, and beam elements for diagonals and roof structure, utilizing multipoint constraints for node connections. The connections between cold-formed steel profiles were modelled using fasteners that exhibit non-linear force-slip behavior. The structure's response was analyzed at both service and ultimate limit states, leading to the proposal of various retrofitting methods, such as the use of Ultra-High-Performance Concrete (UHPC) for columns, additional gusset plates, and profile doubling. The primary output of this study is a comparative analysis between traditional structural modeling approaches and more detailed nonlinear modeling techniques, providing insights into the accuracy and efficiency of different strategies for cold-formed steel structures. This research contributes to the understanding of advanced modeling techniques for cold-formed steel structures and offers practical insights for engineers and researchers involved in structural retrofitting and sustainable construction.

Advanced nonlinear analysis and life cycle assessment of a retrofitted steel portal frame for continued use

Konferenz ArODES

Joanna Nseir, Lucile Schulthess, Thomas Jusselme, Alexandru Chira

SDSS 2025 : The International Colloqium on Stability and Ductility of Steel Structures

Link zur Konferenz

Zusammenfassung:

This study presents a detailed investigation into the retrofitting of an aging steel portal frame, originally serving as a parking facility for public transport. As part of a broader strategy for extending the service life of existing structures, it combines advanced modelling with life cycle assessment to evaluate the technical and environmental benefits of retrofitting. The structure, featuring welded and bolted joints with lateral stability from a concrete shear wall and Saint Andrew’s cross bracing, was surveyed using 3D laser scanning. This enabled a precise digital model for further analysis. A 3D nonlinear finite element model was built in Abaqus, accounting for all nonlinearity sources. Shell and solid elements were used to model structural parts and connections. Several retrofitting options were examined for service and ultimate limit states. Key outcomes include advanced modelling techniques for structural analysis and environmental impact evaluation of retrofitting through comparative LCA. The study demonstrates the potential of retrofitting for the continued use of existing steel structures.

2019

The role of local buckling in the determination of H.S.S. rotational capacity

Konferenz

Elsy Saloumi, Marielle Hayeck, Nseir Joanna, Nicolas Boissonnade

Structural Stability Research Council Annual Stability Conference, 01.08.2019 - 04.08.2019, USA

2017

Stability and resistance of hollow section steel beam-columns

Konferenz

Nseir Joanna

Annual Stability Conference Structural Stability Research Council, 01.04.2017 - 04.04.2017, USA

Errungenschaften

PEOPLE@HES-SO
Verzeichnis der Mitarbeitenden und Kompetenzen

Nseir Joanna

Professeure HES associée

Hauptkompetenzen

Ingénierie structurale

Construction en acier

Modélisation numérique

Réemploi des structures en acier

Professeure HES associée

PEOPLE@HES-SO Verzeichnis der Mitarbeitenden und Kompetenzen

Nseir Joanna

Professeure HES associée

Hauptkompetenzen

Ingénierie structurale

Construction en acier

Modélisation numérique

Réemploi des structures en acier

Professeure HES associée

PEOPLE@HES-SO
Verzeichnis der Mitarbeitenden und Kompetenzen