Ph.D. student Position -MISCEA thesis offer ESR16 – Structural design and optimisation of thin shell shallow foundation

Shallow foundations are ubiquitous and bear a massive environmental footprint, most of which due to the use of steel and concrete [1]. A survey conducted on 200 projects shows that 50% of structural material is in foundations, and that foundations account for 30% of the carbon footprint the construction stage [2]. The ever-growing environmental concerns challenge however this building technique, which is structurally inefficient. Solutions aiming to reduce the mass of reinforced concrete foundations have been explored since the twentieth century [3]. Conical and funicular foundations have been used in the early twentieth century while Hispano-mexican engineer Felix Candela has used Hyperbolic Paraboloids foundations for numerous projects in Mexico in the 1950’s and 1960’s, as shown in Figure 1. However, the steady increase in labour cost in the twentieth century shifted the technological solutions towards less material-efficient and more labour efficient solutions. The development of Computer-Aided Manufacturing techniques is a promising way to find a new compromise between economical and environmental cost by lowering the marginal cost of production of complex artifacts. There is therefore an opportunity to re-explore the potential of shape and topology optimization for shallow foundations.

The literature on shape and topology optimization in architecture is much more oriented towards the optimization of structures rather than foundations. In addition to shell structures, and after the seminal work of Michell [4], engineers have used architected slabs to reduce their weight. Pier Luigi Nervi is one of the most prominent promoters of waffle slabs where ribs follow isostatic lines. However, this strategy was abandoned due to the cost of labor and formworks, which is unbearable in today’s economy [5]. The sustainability of ribbed floors built with conventional techniques can also be questioned due to the wastes implied by the high level of customization of the structure [5].

In the last decade, numerous research groups have tackled the topic of structural optimization through the lens of digital fabrication technologies [6]. As an example, large-scale 3D concrete printing (3DCP) allows customization without wastes, since the technique completely avoid formworks and temporary supports. Other techniques combine fabric formworks with spraying or casting [7,8,9]. While the experiments conducted recently are promising and seem to show a path towards higher material efficiency, not a single one focuses on shallow foundations. Concurrently, the continuing explorations on conical foundations use very simplistic models for load distributions than do not use the full potential of recent advances in nonlinear finite element formulations [10]. There is thus a promising research potential for developing numerical design and fabrication techniques for optimizing the material usage in shallow foundations.

These considerations led Laboratoire Navier to initiate a research program on the optimization of shallow foundations, with a Master thesis in 2023 and a PhD thesis, started in 2024. The present offer concerns another PhD thesis oriented towards design aspects and will build upon the results of the first PhD.Requirements

Research FieldEngineering » Mechanical engineeringEducation LevelMaster Degree or equivalent

Skills/Qualifications

Relevant course of professional experience: Finite Element Modelling, Soil MechanicsLanguagesENGLISHLevelExcellent

Additional Information

Eligibility criteria

Description of the project and the candidates’ eligibity criteria :

This position will be part of the EU-funded project MISCEA, which is an ambitious inter- and multidisciplinary Doctoral Training Network under the Horizon-Europe Marie Skłodowska-Curie Actions. 

PhD candidates’ can be of any anationality but you have to meet these eligibity criteria :

• Not being a current employee working at ENPC.
• Not having resided or carried out their main activity (work, studies, etc) in France for more than 12 months during the past 36 months immediately before the deadline of the MISCEA Programme’s call. Compulsory national service, short stays such as holidays and time spent as part of a procedure for obtaining refugee status under the Geneva Convention are not taken into account.
• Holding a Master’s degree (or about to obtain one) or having a University degree equivalent to a European Master’s degree (5-year duration) at the deadline of the MISCEA Programme’s call.
• Researchers must be doctoral candidates, i.e. not already in possession of a doctoral degree at the deadline of the co-funded programme’s call. Researchers who have successfully defended their doctoral thesis but who have not yet formally been awarded the doctoral degree will NOT be considered eligible.
• Signing a declaration of the veracity of the information provided (Declaration of honour, free of form).

If you comply with the eligibility criteria and you wish to submit your application, you must :

• Contact the thesis supervisor and explain your thesis project to her/him so that she/he validates your application.
• Submit a 5-pages thesis proposal under the proposed research areas, with the agreement of the future supervisor. Additionally, to the submission of the 5-pages thesis proposal, the applicant will have to complete an ethics checklist based on ethics guidance from the HorizonEurope programme guide.
• English-translated transcripts from the master’s degree or equivalent.
• Any specific requirements of the Doctoral School corresponding to the targeted MISCEA
  fellowship offer.
• English curriculum vitae, including information about the level on English language knowledge.
• A motivation letter. 
• One letter of reference, at least.

Templates are available on the MISCEA website (link).

Then your candidature is complete, please send inquiries to miscea-program@enpc.fr

Additional comments

The present offer of a doctoral contract in France is for a period of three years.

Full-Time employment : estimated monthly brut salary : ~2700euros (estimated monthly net salary before income taxes: ~2100euros)